WorldWideScience

Sample records for single-mode thermal field

  1. Exact decoherence dynamics of a single-mode optical field

    International Nuclear Information System (INIS)

    An, J.-H.; Yeo Ye; Oh, C.H.

    2009-01-01

    We apply the influence-functional method of Feynman and Vernon to the study of a single-mode optical field that interacts with an environment at zero temperature. Using the coherent-state formalism of the path integral, we derive a generalized master equation for the single-mode optical field. Our analysis explicitly shows how non-Markovian effects manifest in the exact decoherence dynamics for different environmental correlation time scales. Remarkably, when these are equal to or greater than the time scale for significant change in the system, the interplay between the backaction-induced coherent oscillation and the dissipative effect of the environment causes the non-Markovian effect to have a significant impact not only on the short-time behavior but also on the long-time steady-state behavior of the system.

  2. Response of two-band systems to a single-mode quantized field

    Science.gov (United States)

    Shi, Z. C.; Shen, H. Z.; Wang, W.; Yi, X. X.

    2016-03-01

    The response of topological insulators (TIs) to an external weakly classical field can be expressed in terms of Kubo formula, which predicts quantized Hall conductivity of the quantum Hall family. The response of TIs to a single-mode quantized field, however, remains unexplored. In this work, we take the quantum nature of the external field into account and define a Hall conductance to characterize the linear response of a two-band system to the quantized field. The theory is then applied to topological insulators. Comparisons with the traditional Hall conductance are presented and discussed.

  3. Influence of photo- and thermal bleaching on pre-irradiation low water peak single mode fibers

    Science.gov (United States)

    Yin, Jianchong; Wen, Jianxiang; Luo, Wenyun; Xiao, Zhongyin; Chen, Zhenyi; Wang, Tingyun

    2011-12-01

    Reducing the radiation-induced transmission loss in low water peak single mode fiber (LWP SMF) has been investigated by using photo-bleaching method with 980nm pump light source and using thermal-bleaching method with temperature control system. The results show that the radiation-induced loss of pre-irradiation optical fiber can be reduced effectively with the help of photo-bleaching or thermal-bleaching. Although the effort of photo-bleaching is not as significant as thermal-bleaching, by using photo-bleaching method, the loss of fiber caused by radiation-induced defects can be reduced best up to 49% at 1310nm and 28% at 1550nm in low pre-irradiation condition, the coating of the fiber are not destroyed, and the rehabilitating time is just several hours, while self-annealing usually costs months' time. What's more, the typical high power LASER for photo-bleaching can be 980nm pump Laser Diode, which is very accessible.

  4. Open quantum systems and the two-level atom interacting with a single mode of the electromagnetic field

    International Nuclear Information System (INIS)

    Sandulescu, A.; Stefanescu, E.

    1987-07-01

    On the basis of Lindblad theory of open quantum systems we obtain new optical equations for the system of two-level atom interacting with a single mode of the electromagnetic field. The conventional Block equations in a generalized form with field phases are obtained in the hypothesis that all the terms are slowly varying in the rotating frame.(authors)

  5. Analytical Expression for the Electric Field of the Single Mode Laser ...

    African Journals Online (AJOL)

    The simplest model of the laser is that of a single mode system homogenously broadened. The dynamical behavior of this laser is described by three differential equations, called Haken-Lorenz equations[1], similar to the Lorenz model [1] already known to predict deterministic chaos. In previous recent work [5-7] we have ...

  6. Single-Mode VCSELs

    Science.gov (United States)

    Larsson, Anders; Gustavsson, Johan S.

    The only active transverse mode in a truly single-mode VCSEL is the fundamental mode with a near Gaussian field distribution. A single-mode VCSEL produces a light beam of higher spectral purity, higher degree of coherence and lower divergence than a multimode VCSEL and the beam can be more precisely shaped and focused to a smaller spot. Such beam properties are required in many applications. In this chapter, after discussing applications of single-mode VCSELs, we introduce the basics of fields and modes in VCSELs and review designs implemented for single-mode emission from VCSELs in different materials and at different wavelengths. This includes VCSELs that are inherently single-mode as well as inherently multimode VCSELs where higher-order modes are suppressed by mode selective gain or loss. In each case we present the current state-of-the-art and discuss pros and cons. At the end, a specific example with experimental results is provided and, as a summary, the most promising designs based on current technologies are identified.

  7. Thermal Effects on the Single-Mode Regime of Distributed Modal Filtering Rod Fiber

    DEFF Research Database (Denmark)

    Coscelli, Enrico; Poli, Federica; Alkeskjold, Thomas Tanggaard

    2012-01-01

    Power scaling of fiber laser systems requires the development of innovative active fibers, capable of providing high pump absorption, ultralarge effective area, high-order mode suppression, and resilience to thermal effects. Thermally induced refractive index change has been recently appointed...... as one major limitation to the achievable power, causing degradation of the modal properties and preventing to obtain stable diffraction-limited output beam. In this paper, the effects of thermally induced refractive index change on the guiding properties of a double-cladding distributed modal filtering...

  8. High and tunable spin current induced by magnetic-electric fields in a single-mode spintronic device

    International Nuclear Information System (INIS)

    Bala Kumar, S; Jalil, M B A; Tan, S G; Liang, G-C

    2009-01-01

    We proposed that a viable form of spin current transistor is one to be made from a single-mode device which passes electrons through a series of magnetic-electric barriers built into the device. The barriers assume a wavy spatial profile across the conduction path due to the inevitable broadening of the magnetic fields. Field broadening results in a linearly increasing vector potential across the conduction channel, which increases spin polarization. We have identified that the important factors for generating high spin polarization and conductance modulation are the low source-drain bias, the broadened magnetic fields, and the high number of FM gates within a fixed channel length.

  9. Interaction of a single mode field cavity with the 1D XY model: Energy spectrum

    International Nuclear Information System (INIS)

    Tonchev, H; Donkov, A A; Chamati, H

    2016-01-01

    In this work we use the fundamental in quantum optics Jaynes-Cummings model to study the response of spin 1/2chain to a single mode of a laser light falling on one of the spins, a focused interaction model between the light and the spin chain. For the spin-spin interaction along the chain we use the XY model. We report here the exact analytical results, obtained with the help of a computer algebra system, for the energy spectrum in this model for chains of up to 4 spins with nearest neighbors interactions, either for open or cyclic chain configurations. Varying the sign and magnitude of the spin exchange coupling relative to the light-spin interaction we have investigated both cases of ferromagnetic or antiferromagnetic spin chains. (paper)

  10. The entanglement of two moving atoms interacting with a single-mode field via a three-photon process

    International Nuclear Information System (INIS)

    Chao, Wu; Mao-Fa, Fang

    2010-01-01

    In this paper, the entanglement of two moving atoms induced by a single-mode field via a three-photon process is investigated. It is shown that the entanglement is dependent on the category of the field, the average photon number N, the number p of half-wave lengths of the field mode and the atomic initial state. Also, the sudden death and the sudden birth of the entanglement are detected in this model and the results show that the existence of the sudden death and the sudden birth depends on the parameter and the category of the mode field. In addition, the three-photon process is a higher order nonlinear process. (general)

  11. ANALYTICAL EXPRESSION FOR THE ELECTRIC FIELD OF THE SINGLE MODE LASER HOMOGENEOUS BROADENING IN THE PULSE REGIME

    Directory of Open Access Journals (Sweden)

    S. Ayadi

    2015-07-01

    Full Text Available The simplest model of the laser is that of a single mode system homogenously broadened. The dynamical behavior of this laser is described by three differential equations, called Haken-Lorenz equations[1],  similar to the Lorenz model [1] already known to predict deterministic chaos. In previous recent work [5-7] we have proposed a simple harmonic expansion method to obtain a series of harmonics terms that yield analytical solutions to the laser equations. ¶This method allows us to derive an analytical expression of the laser field amplitude  when this last  undergoes a  periodic oscillations around zero mean value. We also obtain an analytical expression of the pulsing frequency.

  12. Correlated motion of two atoms trapped in a single-mode cavity field

    International Nuclear Information System (INIS)

    Asboth, Janos K.; Domokos, Peter; Ritsch, Helmut

    2004-01-01

    We study the motion of two atoms trapped at distant positions in the field of a driven standing-wave high-Q optical resonator. Even without any direct atom-atom interaction the atoms are coupled through their position dependent influence on the intracavity field. For sufficiently good trapping and low cavity losses the atomic motion becomes significantly correlated and the two particles oscillate in their wells preferentially with a 90 deg. relative phase shift. The onset of correlations seriously limits cavity cooling efficiency, raising the achievable temperature to the Doppler limit. The physical origin of the correlation can be traced back to a cavity mediated crossfriction, i.e., a friction force on one particle depending on the velocity of the second particle. Choosing appropriate operating conditions allows for engineering these long range correlations. In addition this cross-friction effect can provide a basis for sympathetic cooling of distant trapped clouds

  13. 3 kW single stage all-fiber Yb-doped single-mode fiber laser for highly reflective and highly thermal conductive materials processing

    Science.gov (United States)

    Ikoma, S.; Nguyen, H. K.; Kashiwagi, M.; Uchiyama, K.; Shima, K.; Tanaka, D.

    2017-02-01

    A 3 kW single stage all-fiber Yb-doped single-mode fiber laser with bi-directional pumping configuration has been demonstrated. Our newly developed high-power LD modules are employed for a high available pump power of 4.9 kW. The length of the delivery fiber is 20 m which is long enough to be used in most of laser processing machines. An output power of 3 kW was achieved at a pump power of 4.23 kW. The slope efficiency was 70%. SRS was able to be suppressed at the same output power by increasing ratio of backward pump power. The SRS level was improved by 5dB when 57% backward pump ratio was adopted compared with the case of 50%. SRS was 35dB below the laser power at the output power of 3 kW even with a 20-m delivery fiber. The M-squared factor was 1.3. Single-mode beam quality was obtained. To evaluate practical utility of the 3 kW single-mode fiber laser, a Bead-on-Plate (BoP) test onto a pure copper plate was executed. The BoP test onto a copper plate was made without stopping or damaging the laser system. That indicates our high power single-mode fiber lasers can be used practically in processing of materials with high reflectivity and high thermal conductivity.

  14. Effects of an applied low frequency field on the dynamics of a two-level atom interacting with a single-mode field

    International Nuclear Information System (INIS)

    Xun-Wei, Xu; Nian-Hua, Liu

    2010-01-01

    The effects of an applied low frequency field on the dynamics of a two-level atom interacting with a single-mode field are investigated. It is shown that the time evolution of the atomic population is mainly controlled by the coupling constants and the frequency of the low frequency field, which leads to a low frequency modulation function for the time evolution of the upper state population. The amplitude of the modulation function becomes larger as the coupling constants increase. The frequency of the modulation function is proportional to the frequency of the low frequency field, and decreases with increasing coupling constant. (classical areas of phenomenology)

  15. Quantum dynamics of a BEC interacting with a single-mode quantized field in the presence of interatom collisions

    Energy Technology Data Exchange (ETDEWEB)

    Ghasemian, E. [Atomic and Molecular Group, Faculty of Physics, Yazd University, Yazd (Iran, Islamic Republic of); Tavassoly, M.K., E-mail: mktavassoly@yazd.ac.ir [Atomic and Molecular Group, Faculty of Physics, Yazd University, Yazd (Iran, Islamic Republic of); Photonics Research Group, Engineering Research Center, Yazd University, Yazd (Iran, Islamic Republic of); The Laboratory of Quantum Information Processing, Yazd University, Yazd (Iran, Islamic Republic of)

    2016-09-23

    In this paper, we consider a model in which N two-level atoms in a Bose–Einstein condensate (BEC) interact with a single-mode quantized laser field. Our goal is to investigate the quantum dynamics of atoms in the BEC in the presence of interatom interactions. To achieve the purpose, at first, using the collective angular momentum operators, we try to reduce the dynamical Hamiltonian of the system to a well-known Jaynes–Cummings like model (JCM). We also use the Dicke model to construct the state of atomic subsystem, by which the analytical solution of the system may be obtained. Then, we analyze the atomic population inversion, the degree of entanglement between the “atoms in BEC” and the “field” as well as the Mandel parameter. Numerical results show that, the atomic population inversion, atom-field entanglement and quantum statistics of photons are very sensitive to the evolved parameters in the model (and so can be well-adjusted), such as the number of atoms in BEC, the intensity of initial field, the interatom coupling constant and detuning. To investigate the entanglement properties, we pay attention to the entropy and linear entropy. It is shown that, oscillations in the two entropy criteria may be seen, with some maxima of entanglement at some moments of time. Finally, looking for the quantum statistics, we evaluate the Mandel parameter, by which we demonstrate the sub-Poissonian statistics and so the nonclassical characteristics of the field state of system. Collapse-revival phenomenon, which is a distinguishable nonclassical characteristic of the system, can be apparently observed in the atomic population inversion and the Mandel parameter. - Highlights: • N two-level atoms in a BEC interacting with a laser field in the presence of interatom interactions is considered. • The atomic population inversion, degree of entanglement between the “atoms in BEC” and the “field” and the Mandel parameter are investigated. • Collapse

  16. Experimental demonstration of all-optical weak magnetic field detection using beam-deflection of single-mode fiber coated with cobalt-doped nickel ferrite nanoparticles.

    Science.gov (United States)

    Pradhan, Somarpita; Chaudhuri, Partha Roy

    2015-07-10

    We experimentally demonstrate single-mode optical-fiber-beam-deflection configuration for weak magnetic-field-detection using an optimized (low coercive-field) composition of cobalt-doped nickel ferrite nanoparticles. Devising a fiber-double-slit type experiment, we measure the surrounding magnetic field through precisely measuring interference-fringe yielding a minimum detectable field ∼100  mT and we procure magnetization data of the sample that fairly predicts SQUID measurement. To improve sensitivity, we incorporate etched single-mode fiber in double-slit arrangement and recorded a minimum detectable field, ∼30  mT. To further improve, we redefine the experiment as modulating fiber-to-fiber light-transmission and demonstrate the minimum field as 2.0 mT. The device will be uniquely suited for electrical or otherwise hazardous environments.

  17. Single-mode optical fibres

    CERN Document Server

    Cancellieri, G

    1991-01-01

    This book describes signal propagation in single-mode optical fibres for telecommunication applications. Such description is based on the analysis of field propagation, considering waveguide properties and also some of the particular characteristics of the material fibre. The book covers such recent advances as, coherent transmissions; optical amplification; MIR fibres; polarization maintaining; polarization diversity and photon counting.

  18. Linear entropy and collapse–revival phenomenon for a general formalism N-type four-level atom interacting with a single-mode field

    Science.gov (United States)

    Eied, A. A.

    2018-05-01

    In this paper, the linear entropy and collapse-revival phenomenon through the relation ( -{\\bar{n}}) in a system of N-configuration four-level atom interacting with a single-mode field with additional forms of nonlinearities of both the field and the intensity-dependent atom-field coupling functional are investigated. A factorization of the initial density operator is assumed, considering the field to be initially in a squeezed coherent states and the atom initially in its most upper excited state. The dynamical behavior of the linear entropy and the time evolution of ( -{\\bar{n}}) are analyzed. In particular, the effects of the mean photon number, detuning, Kerr-like medium and the intensity-dependent coupling functional on the entropy and the evolution of ( -{\\bar{n}}) are examined.

  19. Phase transitions and Heisenberg limited metrology in an Ising chain interacting with a single-mode cavity field

    DEFF Research Database (Denmark)

    Gammelmark, Søren; Mølmer, Klaus

    2011-01-01

    We investigate the thermodynamics of a combined Dicke and Ising model that exhibits a rich phenomenology arising from the second-order and quantum phase transitions from the respective models. The partition function is calculated using mean-field theory, and the free energy is analyzed in detail...... to determine the complete phase diagram of the system. The analysis reveals both first- and second-order Dicke phase transitions into a super-radiant state, and the cavity mean field in this regime acts as an effective magnetic field, which restricts the Ising chain dynamics to parameter ranges away from...... the Ising phase transition. Physical systems with first-order phase transitions are natural candidates for metrology and calibration purposes, and we apply filter theory to show that the sensitivity of the physical system to temperature and external fields reaches the 1/N Heisenberg limit....

  20. Self-centering fiber alignment structures for high-precision field installable single-mode fiber connectors

    Science.gov (United States)

    Van Erps, Jürgen; Ebraert, Evert; Gao, Fei; Vervaeke, Michael; Berghmans, Francis; Beri, Stefano; Watté, Jan; Thienpont, Hugo

    2014-05-01

    There is a steady increase in the demand for internet bandwidth, primarily driven by cloud services and high-definition video streaming. Europe's Digital Agenda states the ambitious objective that by 2020 all Europeans should have access to internet at speeds of 30Mb/s or above, with 50% or more of households subscribing to connections of 100Mb/s. Today however, internet access in Europe is mainly based on the first generation of broadband, meaning internet accessed over legacy telephone copper and TV cable networks. In recent years, Fiber-To-The-Home (FTTH) networks have been adopted as a replacement of traditional electrical connections for the `last mile' transmission of information at bandwidths over 1Gb/s. However, FTTH penetration is still very low (economies. The main reason for this is the high deployment cost of FTTH networks. Indeed, the success and adoption of optical access networks critically depend on the quality and reliability of connections between optical fibers. In particular a further reduction of insertion loss of field- installable connectors must be achieved without a significant increase in component cost. This requires precise alignment of fibers that can differ in terms of ellipticity, eccentricity or diameter and seems hardly achievable using today's widespread ferrule-based alignment systems. In this paper, we present a field-installable connector based on deflectable/compressible spring structures, providing a self-centering functionality for the fiber. This way, it can accommodate for possible fiber cladding diameter variations (the tolerance on the cladding diameter of G.652 fiber is typically +/-0.7μm). The mechanical properties of the cantilever are derived through an analytical approximation and a mathematical model of the spring constant, and finite element-based simulations are carried out to find the maximum first principal stress as well as the stress distribution distribution in the fiber alignment structure. Elastic

  1. Opto-mechanical design of a buckling cavity in a novel high-performance outside-plant robust field installable single-mode fibre connector

    Science.gov (United States)

    Ebraert, Evert; Van Erps, Jürgen; Beri, Stefano; Watté, Jan; Thienpont, Hugo

    2014-05-01

    Fibre-to-the-home (FTTH) networks provide an ideal means to reach the goal the European Union has set to provide 50 % of the households with a broadband connection faster than 100 Mb/s. Deployment of FTTH networks, which is still costly today, could be significantly boosted by novel ferrule-less connectors which don't require highly skilled personnel and allow installation in the field. We propose a ferrule-less connector in which two single-mode fibres (SMFs) are aligned and maintain physical contact by ensuring that at least one fibre is in a buckled state. To this end, we design a cavity in which a fibre can buckle in a controlled way. Using finite element analysis simulations to investigate the shape of the formed buckle for various buckling cavity lengths, we show that it can be accurately approximated by a cosine function. In addition, the optical performance of a buckled SMF is investigated by bending loss calculations and simulations. We show a good agreement between the analytical and the simulated bending loss results for a G.652 fibre at a wavelength of 1550 nm. Buckling cavity lengths smaller than 20 mm should be avoided to keep the optical bending loss due to buckling below 0.1 dB. In this case the cavity height should at least be 2 mm to avoid mechanical confinement of the fibre.

  2. Near field intensity pattern at the output of silica-based graded-index multimode fibers under selective excitation with a single-mode fiber

    NARCIS (Netherlands)

    Tsekrekos, C.P.; Smink, R.W.; Hon, de B.P.; Tijhuis, A.G.; Koonen, A.M.J.

    2007-01-01

    Abstract: Selective excitation of graded-index multimode fibers (GIMMFs) with a single-mode fiber (SMF) has gained increased interest for telecommunication applications. It has been proposed as a way to enhance the transmission bandwidth of GI-MMF links and/or create parallel communication channels

  3. WORKSHOP: Thermal field theory

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1989-04-15

    The early history of the Universe is a crucial testing ground for theories of elementary particles. Speculative ideas about the constituents of matter and their interactions are reinforced if they are consistent with what we suppose happened near the beginning of time and discarded if they are not. The cosmological consequences of these theories are usually deduced using a general statistical approach called thermal field theory. Thus, 75 physicists from thirteen countries met in Cleveland, Ohio, last October for the first 'Workshop on Thermal Field Theories and their Applications'.

  4. Quantum entanglement and position–momentum entropic squeezing of a moving Lambda-type three-level atom interacting with a single-mode quantized field with intensity-dependent coupling

    International Nuclear Information System (INIS)

    Faghihi, M J; Tavassoly, M K

    2013-01-01

    In this paper, we study the interaction between a moving Λ-type three-level atom and a single-mode cavity field in the presence of intensity-dependent atom–field coupling. After obtaining the state vector of the entire system explicitly, we study the nonclassical features of the system such as quantum entanglement, position–momentum entropic squeezing, quadrature squeezing and sub-Poissonian statistics. According to the obtained numerical results we illustrate that the squeezed period, the duration of entropy squeezing and the maximal squeezing can be controlled by choosing the appropriate nonlinearity function together with entering the atomic motion effect by the suitable selection of the field-mode structure parameter. Also, the atomic motion, as well as the nonlinearity function, leads to the oscillatory behaviour of the degree of entanglement between the atom and field. (paper)

  5. Quantum entanglement and position-momentum entropic squeezing of a moving Lambda-type three-level atom interacting with a single-mode quantized field with intensity-dependent coupling

    Science.gov (United States)

    Faghihi, M. J.; Tavassoly, M. K.

    2013-07-01

    In this paper, we study the interaction between a moving Λ-type three-level atom and a single-mode cavity field in the presence of intensity-dependent atom-field coupling. After obtaining the state vector of the entire system explicitly, we study the nonclassical features of the system such as quantum entanglement, position-momentum entropic squeezing, quadrature squeezing and sub-Poissonian statistics. According to the obtained numerical results we illustrate that the squeezed period, the duration of entropy squeezing and the maximal squeezing can be controlled by choosing the appropriate nonlinearity function together with entering the atomic motion effect by the suitable selection of the field-mode structure parameter. Also, the atomic motion, as well as the nonlinearity function, leads to the oscillatory behaviour of the degree of entanglement between the atom and field.

  6. Dynamics of entropy and nonclassical properties of the state of a Λ-type three-level atom interacting with a single-mode cavity field with intensity-dependent coupling in a Kerr medium

    International Nuclear Information System (INIS)

    Faghihi, M J; Tavassoly, M K

    2012-01-01

    In this paper, we study the interaction between a three-level atom and a quantized single-mode field with ‘intensity-dependent coupling’ in a ‘Kerr medium’. The three-level atom is considered to be in a Λ-type configuration. Under particular initial conditions, which may be prepared for the atom and the field, the dynamical state vector of the entire system will be explicitly obtained, for the arbitrary nonlinearity function f(n) associated with any physical system. Then, after evaluating the variation of the field entropy against time, we will investigate the quantum statistics as well as some of the nonclassical properties of the introduced state. During our calculations we investigate the effects of intensity-dependent coupling, Kerr medium and detuning parameters on the depth and domain of the nonclassicality features of the atom–field state vector. Finally, we compare our obtained results with those of V-type three-level atoms. (paper)

  7. Dynamics of entropy and nonclassical properties of the state of a Λ-type three-level atom interacting with a single-mode cavity field with intensity-dependent coupling in a Kerr medium

    Science.gov (United States)

    Faghihi, M. J.; Tavassoly, M. K.

    2012-02-01

    In this paper, we study the interaction between a three-level atom and a quantized single-mode field with ‘intensity-dependent coupling’ in a ‘Kerr medium’. The three-level atom is considered to be in a Λ-type configuration. Under particular initial conditions, which may be prepared for the atom and the field, the dynamical state vector of the entire system will be explicitly obtained, for the arbitrary nonlinearity function f(n) associated with any physical system. Then, after evaluating the variation of the field entropy against time, we will investigate the quantum statistics as well as some of the nonclassical properties of the introduced state. During our calculations we investigate the effects of intensity-dependent coupling, Kerr medium and detuning parameters on the depth and domain of the nonclassicality features of the atom-field state vector. Finally, we compare our obtained results with those of V-type three-level atoms.

  8. Single-mode biological distributed feedback laser

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Maier-Flaig, Florian; Lemmer, Uli

    2013-01-01

    Single-mode second order distributed feedback (DFB) lasers of riboflavin (vitamin B2) doped gelatine films on nanostructured low refractive index material are demonstrated. Manufacturing is based on a simple UV nanoimprint and spin-coating. Emission wavelengths of 543 nm and 562 nm for two...

  9. Alcohol sensor based on single-mode-multimode-single-mode fiber structure

    Science.gov (United States)

    Mefina Yulias, R.; Hatta, A. M.; Sekartedjo, Sekartedjo

    2016-11-01

    Alcohol sensor based on Single-mode -Multimode-Single-mode (SMS) fiber structure is being proposed to sense alcohol concentration in alcohol-water mixtures. This proposed sensor uses refractive index sensing as its sensing principle. Fabricated SMS fiber structure had 40 m of multimode length. With power input -6 dBm and wavelength 1550 nm, the proposed sensor showed good response with sensitivity 1,983 dB per % v/v with measurement range 05 % v/v and measurement span 0,5% v/v.

  10. Tripartite entanglement of bosonic systems in a noninertial frame beyond the single- mode approximation

    Directory of Open Access Journals (Sweden)

    M Soltani

    2015-12-01

    Full Text Available In this work, we generalize the entanglement of three-qbit Bosonic systems beyond the single-mode approximation when one of the observers is accelerated. For this purpose, we review the effects of acceleration on field modes and quantum states. The single-mode approximation and beyond the single-mode approximation methods are introduced. After this brief introduction, the main problem of this paper, tripartite entanglement of bosonic systems in a noninertial frame beyond the single- mode approximation is investigated. The tripartite entangled states have different classes with GHZ and W states being most important. Here, we choose &pi-tangle as a measure of tripartite entanglement. If the three parties share GHZ state, the corresponding &pi-tangle will increase by increasing acceleration for some Unruh modes. This phenomenon, increasing entanglement, has never been observed in the single-mode approximation for bosonic case. Moreover, the &pi-tangle dose not exhibit a monotonic behavior with increasing acceleration. In the infinite acceleration limit, the &pi-tangle goes to different nonzero values for distinct Unruh modes. Unlike GHZ state, the entanglement of the W state shows only monotonically increasing and decreasing behaviors with increasing acceleration. Also, the entanglement for all possible choices of Unruh modes approaches only 0.176 in the high acceleration limit. Therefore, according to the quantum entanglement, there is no distinction between the single-mode approximation and beyond the single-mode approximation methods in this limit.

  11. Single-mode coherent synchrotron radiation instability

    Directory of Open Access Journals (Sweden)

    S. Heifets

    2003-06-01

    Full Text Available The microwave instability driven by the coherent synchrotron radiation (CSR has been previously studied [S. Heifets and G. V. Stupakov, Phys. Rev. ST Accel. Beams 5, 054402 (2002] neglecting effect of the shielding caused by the finite beam pipe aperture. In practice, the unstable mode can be close to the shielding threshold where the spectrum of the radiation in a toroidal beam pipe is discrete. In this paper, the CSR instability is studied in the case when it is driven by a single synchronous mode. A system of equations for the beam-wave interaction is derived and its similarity to the 1D free-electron laser theory is demonstrated. In the linear regime, the growth rate of the instability is obtained and a transition to the case of continuous spectrum is discussed. The nonlinear evolution of the single-mode instability, both with and without synchrotron damping and quantum diffusion, is also studied.

  12. Current measurements by Faraday rotation in single mode optical fibers

    International Nuclear Information System (INIS)

    Chandler, G.I.; Jahoda, F.C.

    1984-01-01

    Development of techniques for measuring magnetic fields and currents by Faraday rotation in single-mode optical fibers has continued. We summarize the results of attempts to measure the toroidal plasma current in the ZT-40 Reversed-Field-Pinch using multi-turn fiber coils. The fiber response is reproducible and in accord with theory, but the amount and distribution of the stress-induced birefringence in this case are such that prediction of the sensor response at low currents is difficult if not impossible. The low-current difficulty can be overcome by twisting the fiber to induce a circular birefringence bias. We report the results of auxiliary experiments with a fiber that has been twisted with 15 turns per meter and then re-coated to lock the twist in place

  13. Methods of thermal field theory

    Energy Technology Data Exchange (ETDEWEB)

    Mallik, S [Saha Institute of Nuclear Physics, Calcutta (India)

    1998-11-01

    We introduce the basic ideas of thermal field theory and review its path integral formulation. We then discuss the problems of QCD theory at high and at low temperatures. At high temperature the naive perturbation expansion breaks down and is cured by resummation. We illustrate this improved perturbation expansion with the g{sup 2}{phi}{sup 4} theory and then sketch its application to find the gluon damping rate in QCD theory. At low temperature the hadronic phase is described systematically by the chiral perturbation theory. The results obtained from this theory for the quark and the gluon condensates are discussed. (author) 22 refs., 6 figs.

  14. Optimize Etching Based Single Mode Fiber Optic Temperature Sensor

    OpenAIRE

    Ajay Kumar; Dr. Pramod Kumar

    2014-01-01

    This paper presents a description of etching process for fabrication single mode optical fiber sensors. The process of fabrication demonstrates an optimized etching based method to fabricate single mode fiber (SMF) optic sensors in specified constant time and temperature. We propose a single mode optical fiber based temperature sensor, where the temperature sensing region is obtained by etching its cladding diameter over small length to a critical value. It is observed that th...

  15. Crosstalk-Managed Heterogeneous Single-Mode 32-Core Fibre

    DEFF Research Database (Denmark)

    Sasaki, Y.; Fukumoto, Ryohei; Takenaga, Katsuhiro

    2016-01-01

    A heterogeneous single-mode 32-core fibre with a cladding diameter of 243 micrometer is designed and fabricated. The highest core count in single-mode multi-core fibres and low worst-case crosstalk of less than -24 dB/1000 km in C-band are achieved simultaneously....

  16. Low-loss single mode light waveguides in polymer

    Science.gov (United States)

    Sieber, Heinrich; Boehm, Hans-Jürgen; Hollenbach, Uwe; Mohr, Jürgen; Ostrzinski, Ute; Pfeiffer, Karl; Szczurowski, Marcin; Urbanczyk, Waclaw

    2012-06-01

    We report on the development of a UV-lithography manufacturing process for low loss single mode light waveguides in a novel polymer and the characterization of the fabricated components in a broad wavelength range from 808 nm to 1550 nm. The main focus of this work lies in providing a quick and cost efficient production technique for single mode waveguides and low loss integrated optical circuits. To achieve this goal we chose a novel photo-structurable polymer host-guest-system consisting of SU8 and a low refractive dopant monomer. Near and far-field measurements at different wavelengths show that the mode propagating within a well designed integrated waveguide structure and the mode of a standard fiber can exhibit a mode overlap value of approximately 1 and suffer only very low coupling losses. We demonstrate excess loss of 0.14 dB/cm for 808 nm, 0.33 dB/cm for 1310 nm and 2.86 dB/cm for 1550 nm. Typical insertion loss values of straight waveguides with a length of 36 mm are 0.9 dB for 808 nm, 1.5 dB for 1310 nm and 10.4 dB for 1550 nm. Polarization dependent loss was found to be less than 0.2 dB on sets of test structures of 36 mm length. We measured material attenuation in the novel polymer material before cross-linking of approximately 0.04 dB/cm for 808 nm and around 0.20 dB/cm for 1310 nm respectively. The presented production technique is suitable to provide low loss and low cost integrated optical circuits for sensor and communication applications in a broad wavelength range.

  17. Two problems in thermal field theory

    Indian Academy of Sciences (India)

    In this talk, I review recent progress made in two areas of thermal field theory. In par- ticular, I discuss various approaches for the calculation of the quark gluon plasma thermodynamical properties, and the problem of its photon production rate. Keywords. Thermal field theory; quark-gluon plasma. PACS Nos 11.10.Wx; 12.38.

  18. Radiation-induced transient absorption in single mode optical fibers

    International Nuclear Information System (INIS)

    Looney, L.D.; Lyons, P.B.

    1988-01-01

    This paper reviews the measurements conducted by the Los Alamos National Laboratory in support of these NATO efforts wherein radiation-induced transient absorption was measured over time ranges from a few ns to several μs for two single mode fibers. Experimental conditions were varied to provide data for future development of standarized test conditions for single mode fibers. 8 refs., 11 figs

  19. Time-optimal thermalization of single-mode Gaussian states

    Science.gov (United States)

    Carlini, Alberto; Mari, Andrea; Giovannetti, Vittorio

    2014-11-01

    We consider the problem of time-optimal control of a continuous bosonic quantum system subject to the action of a Markovian dissipation. In particular, we consider the case of a one-mode Gaussian quantum system prepared in an arbitrary initial state and which relaxes to the steady state due to the action of the dissipative channel. We assume that the unitary part of the dynamics is represented by Gaussian operations which preserve the Gaussian nature of the quantum state, i.e., arbitrary phase rotations, bounded squeezing, and unlimited displacements. In the ideal ansatz of unconstrained quantum control (i.e., when the unitary phase rotations, squeezing, and displacement of the mode can be performed instantaneously), we study how control can be optimized for speeding up the relaxation towards the fixed point of the dynamics and we analytically derive the optimal relaxation time. Our model has potential and interesting applications to the control of modes of electromagnetic radiation and of trapped levitated nanospheres.

  20. Single-mode hole-assisted fiber as a bending-loss insensitive fiber

    Science.gov (United States)

    Nakajima, Kazuhide; Shimizu, Tomoya; Matsui, Takashi; Fukai, Chisato; Kurashima, Toshio

    2010-12-01

    We investigate the design and characteristics of a single-mode and low bending loss HAF both numerically and experimentally. An air filling fraction S is introduced to enable us to design a HAF with desired characteristics more easily. We show that we can expect to realize a single-mode and low bending loss HAF by considering the S dependence of the bending loss α b and cutoff wavelength λ c as well as their relative index difference Δ dependence. We also show that the mode-field diameter (MFD) and chromatic dispersion characteristics of the single-mode and low bending loss HAF can be tailored by optimizing the distance between the core and the air holes. We also investigate the usefulness of the fabricated HAFs taking the directly modulated transmission and multipath interference (MPI) characteristics into consideration. We show that the designed HAF has sufficient applicability to both analog and digital transmission systems. Our results reveal that the single-mode and low bending loss HAF is beneficial in terms of developing a future fiber to the home (FTTH) network as well as for realizing flexible optical wiring.

  1. High-power single-mode cw dye ring laser

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, H W; Stein, L; Froelich, D; Fugger, B; Welling, H [Technische Univ. Hannover (Germany, F.R.). Inst. fuer Angewandte Physik

    1977-12-01

    Due to spatial hole burning, standing-wave dye lasers require a large amount of selectivity inside the cavity for single-mode operation. The output power of these lasers is limited by losses caused by the frequency selecting elements. In a travelling-wave laser, on the other hand, spatial hole burning does not exist, thereby eliminating the need for high selectivity. A travelling-wave cw dye laser was realized by unidirectional operation of a ring laser, yielding single mode output powers of 1.2 W at 595 nm and of 55 mW in the UV-region with intracavity frequency doubling.

  2. Thermalization of fermionic quantum fields

    International Nuclear Information System (INIS)

    Berges, Juergen; Borsanyi, Szabolcs; Serreau, Julien

    2003-01-01

    We solve the nonequilibrium dynamics of a (3+1)-dimensional theory with Dirac fermions coupled to scalars via a chirally invariant Yukawa interaction. The results are obtained from a systematic coupling expansion of the 2PI effective action to lowest nontrivial order, which includes scattering as well as memory and off-shell effects. The dynamics is solved numerically without further approximation, for different far-from-equilibrium initial conditions. The late-time behavior is demonstrated to be insensitive to the details of the initial conditions and to be uniquely determined by the initial energy density. Moreover, we show that at late time the system is very well characterized by a thermal ensemble. In particular, we are able to observe the emergence of Fermi-Dirac and Bose-Einstein distributions from the nonequilibrium dynamics

  3. Semiconductor and ceramic microstructure made by single mode fiber laser

    International Nuclear Information System (INIS)

    Pawlak, R; Tomczyk, M; Walczak, M; Domagalski, P

    2014-01-01

    In the paper the results of micromachining of 3D microstructures of microsystems made from silicon and alumina ceramic using a single mode fiber laser (1064 nm) are presented. The quality of obtained structures and its smallest dimensions with acceptable maintained quality were examined. The influence of variable parameters of laser processing with changing of mapping scale on geometrical features of structures was identified.

  4. Spatially single-mode source of bright squeezed vacuum

    OpenAIRE

    Pérez, A. M.; Iskhakov, T. Sh.; Sharapova, P.; Lemieux, S.; Tikhonova, O. V.; Chekhova, M. V.; Leuchs, G.

    2014-01-01

    Bright squeezed vacuum, a macroscopic nonclassical state of light, can be obtained at the output of a strongly pumped non-seeded traveling-wave optical parametric amplifier (OPA). By constructing the OPA of two consecutive crystals separated by a large distance we make the squeezed vacuum spatially single-mode without a significant decrease in the brightness or squeezing.

  5. Single-mode multicore fiber for dense space division multiplexing

    DEFF Research Database (Denmark)

    Sasaki, Yusuke; Amma, Yoshimichi; Takenaga, Katsuhiro

    2016-01-01

    Single-mode multicore fiber (SM-MCF) is attractive for high-capacity transmission. Our fabricated SM-MCFs achieve high core count and low crosstalk with a cladding diameter of 230 µm. Characteristics of fan-in/fan-out for the SM-MCFs are also investigated....

  6. Quasi-single-mode homogeneous 31-core fibre

    DEFF Research Database (Denmark)

    Sasaki, Y.; Saitoh, S.; Amma, Y.

    2015-01-01

    A homogeneous 31-core fibre with a cladding diameter of 230 μm for quasi-single-mode transmission is designed and fabricated. LP01-crosstalk of -38.4 dB/11 km at 1550 nm is achieved by using few-mode trench-assisted cores....

  7. Probing quantum entanglement in the Schwarzschild space-time beyond the single-mode approximation

    Science.gov (United States)

    He, Juan; Ding, Zhi-Yong; Ye, Liu

    2018-05-01

    In this paper, we deduce the vacuum structure for Dirac fields in the background of Schwarzschild space-time beyond the single-mode approximation and discuss the performance of quantum entanglement between particle and antiparticle modes of a Dirac field with Hawking effect. It is shown that Hawking radiation does not always destroy the physically accessible entanglement, and entanglement amplification may happen in some cases. This striking result is different from that of the single-mode approximation, which holds that the Hawking radiation can only destroy entanglement. Lastly, we analyze the physically accessible entanglement relation outside the event horizon and demonstrate that the monogamy inequality is constantly established regardless of the choice of given parameters.

  8. Quantum teleportation via noisy bipartite and tripartite accelerating quantum states: beyond the single mode approximation

    Science.gov (United States)

    Zounia, M.; Shamirzaie, M.; Ashouri, A.

    2017-09-01

    In this paper quantum teleportation of an unknown quantum state via noisy maximally bipartite (Bell) and maximally tripartite (Greenberger-Horne-Zeilinger (GHZ)) entangled states are investigated. We suppose that one of the observers who would receive the sent state accelerates uniformly with respect to the sender. The interactions of the quantum system with its environment during the teleportation process impose noises. These (unital and nonunital) noises are: phase damping, phase flip, amplitude damping and bit flip. In expressing the modes of the Dirac field used as qubits, in the accelerating frame, the so-called single mode approximation is not imposed. We calculate the fidelities of teleportation, and discuss their behaviors using suitable plots. The effects of noise, acceleration and going beyond the single mode approximation are discussed. Although the Bell states bring higher fidelities than GHZ states, the global behaviors of the two quantum systems with respect to some noise types, and therefore their fidelities, are different.

  9. Terahertz light-emitting graphene-channel transistor toward single-mode lasing

    Science.gov (United States)

    Yadav, Deepika; Tamamushi, Gen; Watanabe, Takayuki; Mitsushio, Junki; Tobah, Youssef; Sugawara, Kenta; Dubinov, Alexander A.; Satou, Akira; Ryzhii, Maxim; Ryzhii, Victor; Otsuji, Taiichi

    2018-03-01

    A distributed feedback dual-gate graphene-channel field-effect transistor (DFB-DG-GFET) was fabricated as a current-injection terahertz (THz) light-emitting laser transistor. We observed a broadband emission in a 1-7.6-THz range with a maximum radiation power of 10 μW as well as a single-mode emission at 5.2 THz with a radiation power of 0.1 μW both at 100 K when the carrier injection stays between the lower cutoff and upper cutoff threshold levels. The device also exhibited peculiar nonlinear threshold-like behavior with respect to the current-injection level. The LED-like broadband emission is interpreted as an amplified spontaneous THz emission being transcended to a single-mode lasing. Design constraints on waveguide structures for better THz photon field confinement with higher gain overlapping as well as DFB cavity structures with higher Q factors are also addressed towards intense, single-mode continuous wave THz lasing at room temperature.

  10. An optical channel modeling of a single mode fiber

    Science.gov (United States)

    Nabavi, Neda; Liu, Peng; Hall, Trevor James

    2018-05-01

    The evaluation of the optical channel model that accurately describes the single mode fibre as a coherent transmission medium is reviewed through analytical, numerical and experimental analysis. We used the numerical modelling of the optical transmission medium and experimental measurements to determine the polarization drift as a function of time for a fixed length of fibre. The probability distribution of the birefringence vector was derived, which is associated to the 'Poole' equation. The theory and experimental evidence that has been disclosed in the literature in the context of polarization mode dispersion - Stokes & Jones formulations and solutions for key statistics by integration of stochastic differential equations has been investigated. Besides in-depth definition of the single-mode fibre-optic channel, the modelling which concerns an ensemble of fibres each with a different instance of environmental perturbation has been analysed.

  11. Single mode operation of a TEA CO2 laser

    International Nuclear Information System (INIS)

    Wada, Kazuhiro; Tunawaki, Yoshiaki; Yamanaka, Masanobu.

    1993-01-01

    Single mode operation of a TEA CO 2 laser was performed by using an optical system of Fox-Smith type. Laser beam was taken out from the cavity by using a beam splitter, and was reflected by a mirror back to the cavity. By inserting a Fabry-Perot etalon between the splitter and the mirror, beat of laser pulses can be removed completly. (author)

  12. Infrared difficulties with thermal quantum field theories

    International Nuclear Information System (INIS)

    Grandou, T.

    1997-01-01

    Reviewing briefly the two main difficulties encountered in thermal quantum field theories at finite temperature when dealing with the Braaten-Pisarski (BP) resummation program, the motivation is introduced of an analysis relying on the bare perturbation theory, right from the onset. (author)

  13. Nonlinear polarization effects in a birefringent single mode optical fiber

    International Nuclear Information System (INIS)

    Ishiekwene, G.C.; Mensah, S.Y.; Brown, C.S.

    2001-04-01

    The nonlinear polarization effects in a birefringent single mode optical fiber is studied using Jacobi elliptic functions. We find that the polarization state of the propagating beam depends on the initial polarization as well as the intensity of the input light in a complicated way. The Stokes polarization parameters are either periodic or aperiodic depending on the value of the Jacobian modulus. Our calculations suggest that the effective beat length of the fiber can become infinite at a higher critical value of the input power when polarization dependent losses are considered. (author)

  14. Single mode dye-doped polymer photonic crystal lasers

    International Nuclear Information System (INIS)

    Christiansen, Mads B; Buß, Thomas; Smith, Cameron L C; Petersen, Sidsel R; Jørgensen, Mette M; Kristensen, Anders

    2010-01-01

    Dye-doped polymer photonic crystal (PhC) lasers fabricated by combined nanoimprint and photolithography are studied for their reproducibility and stability characteristics. We introduce a phase shift in the PhC lattice that substantially improves the yield of single wavelength emission. Single mode emission and reproducibility of laser characteristics are important if the lasers are to be mass produced in, e.g., optofluidic sensor chips. The fabrication yield is above 85% with highly reproducible wavelengths (within 0.5%), and the temperature dependence on the wavelength is found to be −0.045 or −0.066 nm K -1 , depending on the material

  15. Holograms for laser diode: Single mode optical fiber coupling

    Science.gov (United States)

    Fuhr, P. L.

    1982-01-01

    The low coupling efficiency of semiconductor laser emissions into a single mode optical fibers place a severe restriction on their use. Associated with these conventional optical coupling techniques are stringent alignment sensitivities. Using holographic elements, the coupling efficiency may be increased and the alignment sensitivity greatly reduced. Both conventional and computer methods used in the generation of the holographic couplers are described and diagrammed. The reconstruction geometries used are shown to be somewhat restrictive but substantially less rigid than their conventional optical counterparts. Single and double hologram techniques are examined concerning their respective ease of fabrication and relative merits.

  16. Single mode dye-doped polymer photonic crystal lasers

    DEFF Research Database (Denmark)

    Christiansen, Mads Brøkner; Buss, Thomas; Smith, Cameron

    2010-01-01

    Dye-doped polymer photonic crystal (PhC) lasers fabricated by combined nanoimprint and photolithography are studied for their reproducibility and stability characteristics. We introduce a phase shift in the PhC lattice that substantially improves the yield of single wavelength emission. Single mode...... emission and reproducibility of laser characteristics are important if the lasers are to be mass produced in, e. g., optofluidic sensor chips. The fabrication yield is above 85% with highly reproducible wavelengths (within 0.5%), and the temperature dependence on the wavelength is found to be -0.045 or -0...

  17. Single-mode Laser by Parity-time Symmetry Breaking

    Science.gov (United States)

    2014-11-21

    solenoid -like Pds5B that reside in direct proximity to Wapl and the Smc3-Scc1 in- teraction interface (fig. S13), implying that Wapl and Pds5 control the...accepted 26 September 2014 10.1126/science.1256904 REPORTS ◥ OPTICS Single-mode laser by parity-time symmetry breaking Liang Feng,1* Zi Jing Wong,1...Ren-Min Ma,1* Yuan Wang,1,2 Xiang Zhang1,2† Effective manipulation of cavity resonant modes is crucial for emission control in laser physics and

  18. Mid-Infrared Continuously Tunable Single Mode VECSEL

    Science.gov (United States)

    Khiar, A.; Rahim, M.; Felder, F.; Fill, M.; Zogg, H.

    2011-12-01

    Tunable mid-infrared vertical external cavity surface emitting lasers were developed for the wavelength range around 3.8-3.9 μm and 3.2-3.3 μm, respectively. The devices are based on lead salt materials epitaxially grown by MBE on a Si substrate. The active part consists of PbSe QW in a PbSrSe host layer. Both devices are operated around -20 °C and have output power of several 10 mW. By changing the cavity length, a single mode hop free tuning range up to 80 cm-1 is achieved.

  19. Single-mode surface plasmon distributed feedback lasers.

    Science.gov (United States)

    Karami Keshmarzi, Elham; Tait, R Niall; Berini, Pierre

    2018-03-29

    Single-mode surface plasmon distributed feedback (DFB) lasers are realized in the near infrared using a two-dimensional non-uniform long-range surface plasmon polariton structure. The surface plasmon mode is excited onto a 20 nm-thick, 1 μm-wide metal stripe (Ag or Au) on a silica substrate, where the stripe is stepped in width periodically, forming a 1st order Bragg grating. Optical gain is provided by optically pumping a 450 nm-thick IR-140 doped PMMA layer as the top cladding, which covers the entire length of the Bragg grating, thus creating a DFB laser. Single-mode lasing peaks of very narrow linewidth were observed for Ag and Au DFBs near 882 nm at room temperature. The narrow linewidths are explained by the low spontaneous emission rate into the surface plasmon lasing mode as well as the high quality factor of the DFB structure. The lasing emission is exclusively TM polarized. Kinks in light-light curves accompanied by spectrum narrowing were observed, from which threshold pump power densities can be clearly identified (0.78 MW cm-2 and 1.04 MW cm-2 for Ag and Au DFB lasers, respectively). The Schawlow-Townes linewidth for our Ag and Au DFB lasers is estimated and very narrow linewidths are predicted for the lasers. The lasers are suitable as inexpensive, recyclable and highly coherent sources of surface plasmons, or for integration with other surface plasmon elements of similar structure.

  20. Watt-level widely tunable single-mode emission by injection-locking of a multimode Fabry-Perot quantum cascade laser

    Science.gov (United States)

    Chevalier, Paul; Piccardo, Marco; Anand, Sajant; Mejia, Enrique A.; Wang, Yongrui; Mansuripur, Tobias S.; Xie, Feng; Lascola, Kevin; Belyanin, Alexey; Capasso, Federico

    2018-02-01

    Free-running Fabry-Perot lasers normally operate in a single-mode regime until the pumping current is increased beyond the single-mode instability threshold, above which they evolve into a multimode state. As a result of this instability, the single-mode operation of these lasers is typically constrained to few percents of their output power range, this being an undesired limitation in spectroscopy applications. In order to expand the span of single-mode operation, we use an optical injection seed generated by an external-cavity single-mode laser source to force the Fabry-Perot quantum cascade laser into a single-mode state in the high current range, where it would otherwise operate in a multimode regime. Utilizing this approach, we achieve single-mode emission at room temperature with a tuning range of 36 cm-1 and stable continuous-wave output power exceeding 1 W at 4.5 μm. Far-field measurements show that a single transverse mode is emitted up to the highest optical power, indicating that the beam properties of the seeded Fabry-Perot laser remain unchanged as compared to free-running operation.

  1. Quench Propagation Ignition using Single-Mode Diode Laser

    CERN Document Server

    Trillaud, F; Devred, Arnaud; Fratini, M; Leboeuf, D; Tixador, P

    2005-01-01

    The stability of NbTi-based multifilamentary composite wires subjected to local heat disturbances of short durations is studied in pool boiling helium conditions. A new type of heater is being developed to characterize the superconducting to normal state transition. It relies on a single-mode Diode Laser with an optical fiber illuminating the wire surface. This first paper focuses mainly on the feasibility of this new heater technology and eventually discusses the difficulties related to it. A small overview of Diode Lasers and optical fibers revolving around our application is given. Then, we describe the experimental setup, and present some recorded voltage traces of transition and recovery processes. In addition, we present also some energy and Normal Zone Propagation Velocity data and we outline ameliorations that will be done to the system.

  2. Picosecond chirped pulse compression in single-mode fibers

    International Nuclear Information System (INIS)

    Wenhua Cao; Youwei Zhang

    1995-01-01

    In this paper, the nonlinear propagation of picosecond chirped pulses in single mode fibers has been investigated both analytically and numerically. Results show that downchirped pulses can be compressed owing to normal group-velocity dispersion. The compression ratio depends both on the initial peak power and on the initial frequency chirp of the input pulse. While the compression ratio depends both on the initial peak power and on the initial frequency chirp of the input pulse. While the compression ratio increases with the negative frequency chirp, it decreases with the initial peak power of the input pulse. This means that the self-phase modulation induced nonlinear frequency chirp which is linear and positive (up-chirp) over a large central region of the pulse and tends to cancel the initial negative chirp of the pulse. It is also shown that, as the negative chirped pulse compresses temporally, it synchronously experiences a spectral narrowing

  3. Mid-infrared performance of single mode chalcogenide fibers

    Science.gov (United States)

    Cook, Justin; Sincore, Alex; Tan, Felix; El Halawany, Ahmed; Riggins, Anthony; Shah, Lawrence; Abouraddy, Ayman F.; Richardson, Martin C.; Schepler, Kenneth L.

    2018-02-01

    Due to the intrinsic absorption edge in silica near 2.4 μm, more exotic materials are required to transmit laser power in the IR such as fluoride or chalcogenide glasses (ChGs). In particular, ChG fibers offer broad IR transmission with low losses fibers at four different infrared wavelengths: 2053 nm, 2520 nm and 4550 nm. Polymer clad ChG fibers were drawn with 12.3 μm and 25 μm core diameters. Testing at 2053 nm was accomplished using a > 15 W, CW Tm:fiber laser. Power handling up to 10.2 W with single mode beam quality has been demonstrated, limited only by the available Tm:fiber output power. Anti-reflective coatings were successfully deposited on the ChG fiber facets, allowing up to 90.6% transmission with 12.2 MW/cm2 intensity on the facet. Single mode guidance at 4550 nm was also demonstrated using a quantum cascade laser (QCL). A custom optical system was constructed to efficiently couple the 0.8 NA QCL radiation into the 0.2 NA ChG fiber, allowing for a maximum of 78% overlap between the QCL radiation and fundamental mode of the fiber. With an AR-coated, 25 μm core diameter fiber, >50 mW transmission was demonstrated with > 87% transmission. Finally, we present results on fiber coupling from a free space Cr:ZnSe resonator at 2520 nm.

  4. Thermal inflation with a thermal waterfall scalar field coupled to a light spectator scalar field

    Science.gov (United States)

    Dimopoulos, Konstantinos; Lyth, David H.; Rumsey, Arron

    2017-05-01

    A new model of thermal inflation is introduced, in which the mass of the thermal waterfall field is dependent on a light spectator scalar field. Using the δ N formalism, the "end of inflation" scenario is investigated in order to ascertain whether this model is able to produce the dominant contribution to the primordial curvature perturbation. A multitude of constraints are considered so as to explore the parameter space, with particular emphasis on key observational signatures. For natural values of the parameters, the model is found to yield a sharp prediction for the scalar spectral index and its running, well within the current observational bounds.

  5. Ionization of atoms in a thermal field

    CERN Document Server

    Fröhlich, J; Sigal, I M

    2003-01-01

    We study the stationary states of a quantum mechanical system describing an atom coupled to black-body radiation at positive temperature. The stationary states of the non-interacting system are given by product states, where the particle is in a bound state corresponding to an eigenvalue of the particle Hamiltonian, and the field is in its equilibrium state. We show that if Fermi's Golden Rule predicts that a stationary state disintegrates after coupling to the radiation field then it is unstable, provided the coupling constant is sufficiently small (depending on the temperature). \\\\ \\indent The result is proven by analyzing the spectrum of the thermal Hamiltonian (Liouvillian) of the system within the framework of $W^*$-dynamical systems. A key element of our spectral analysis is the positive commutator method.

  6. Processing of complex shapes with single-mode resonant frequency microwave applicators

    International Nuclear Information System (INIS)

    Fellows, L.A.; Delgado, R.; Hawley, M.C.

    1994-01-01

    Microwave processing is an alternative to conventional composite processing techniques. Single-mode microwave applicators efficiently couple microwave energy into the composite. The application of the microwave energy is greatly affected by the geometry of the composite. In the single mode microwave applicator, two types of modes are available. These modes are best suited to processing flat planar samples or cylindrical samples with geometries that align with the electric fields. Mode-switching is alternating between different electromagnetic modes with the intelligent selection of the modes to alleviate undesirable temperature profiles. This method has improved the microwave heating profiles of materials with complex shapes that do not align with either type of electric field. Parts with two different complex geometries were fabricated from a vinyl toluene/vinyl ester resin with a continuous glass fiber reinforcement by autoclaving and by microwave techniques. The flexural properties of the microwave processed samples were compared to the flexural properties of autoclaved samples. The trends of the mechanical properties for the complex shapes were consistent with the results of experiments with flat panels. This demonstrated that mode-switching techniques are as applicable for the complex shapes as they are for the simpler flat panel geometry

  7. Electrically tunable Brillouin fiber laser based on a metal-coated single-mode optical fiber

    Directory of Open Access Journals (Sweden)

    S.M. Popov

    Full Text Available We explore tunability of the Brillouin fiber laser employing Joule heating. For this purpose, 10-m-length of a metal-coated single-mode optical cavity fiber has been directly included into an electrical circuit, like a conductor wire. With the current up to ∼3.5 A the laser tuning is demonstrated over a spectrum range of ∼400 MHz. The observed laser line broadening up to ∼2 MHz is explained by frequency drift and mode-hoping in the laser caused by thermal noise. Keywords: Brillouin fiber laser, Metal-coated optical fiber, Laser tuning, Fiber sensors

  8. 2-kW single-mode fiber laser employing bidirectional-pump scheme

    Science.gov (United States)

    Zhang, Fan; Zheng, Wenyou; Shi, Pengyang; Zhang, Xinhai

    2018-01-01

    2kW single-mode fiber laser with two cascade home-made cladding light strippers (CLSs) by employing bidirectionalpump scheme has been demonstrated. 2.009 kW signal power is obtained when pump power is 2.63 kW and the slope efficiency is 76.6%. Raman Stokes light is less than -47 dB at 2.009 kW even with a 10-m delivery fiber with core/inner cladding diameter of 20/400um. The beam quality M2<=1.2 and the spectral FWHM bandwidth is 4.34nm. There is no transverse mode instability and the output power stability of +/-0.14% is achieved by special thermal management for a more uniform temperature distribution on the Yb-doped gain fiber.

  9. Temporal description of thermal quantum fields

    International Nuclear Information System (INIS)

    Umezawa, H.; Yamanaka, Y.

    1992-01-01

    In this paper, making use of time-dependent Bogoliubov transformations, the authors develop a calculation technique for time-dependent non-equilibrium systems of quantum fields in a time-representation (t-representation). The corrected one-body propagator in the t-representation turns out to have the form B - 1 (diagonal matrix) B (B being a thermal Bogoliubov matrix). Applying the usual on-shell concept to the diagonal matrix part of the self-energy, we formulate a self-consistent renormalization scheme. This renormalization determines the vacuum and leads to a kinetic equation for the number density parameter, which reduces to the Boltzmann equation in the lowest approximation. This gives the authors the increasing entropy in time (the second law of thermodynamics)

  10. Single-mode annular chirally-coupled core fibers for fiber lasers

    Science.gov (United States)

    Zhang, Haitao; Hao, He; He, Linlu; Gong, Mali

    2018-03-01

    Chirally-coupled core (CCC) fiber can transmit single fundamental mode and effectively suppresses higher-order mode (HOM) propagation, thus improve the beam quality. However, the manufacture of CCC fiber is complicated due to its small side core. To decrease the manufacture difficulty in China, a novel fiber structure is presented, defined as annular chirally-coupled core (ACCC) fiber, replacing the small side core by a larger side annulus. In this paper, we designed the fiber parameters of this new structure, and demonstrated that the new structure has a similar property of single mode with traditional CCC fiber. Helical coordinate system was introduced into the finite element method (FEM) to analyze the mode field in the fiber, and the beam propagation method (BPM) was employed to analyze the influence of the fiber parameters on the mode loss. Based on the result above, the fiber structure was optimized for efficient single-mode transmission, in which the core diameter is 35 μm with beam quality M2 value of 1.04 and an optical to optical conversion efficiency of 84%. In this fiber, fundamental mode propagates in an acceptable loss, while the HOMs decay rapidly.

  11. Radiation resistance characteristics of optical communication system for single mode

    International Nuclear Information System (INIS)

    Ohe, Masamoto; Chigusa, Yoshiki; Kyodo, Tomohisa; Tanaka, Gohtaro; Watanabe, Hajime; Okamoto, Shin-ichi; Yamamoto, Takao.

    1988-01-01

    Optical communication has been utilized also for nuclear power stations and fuel reporocessing plants. As the sufficient safety countermeasures are required there, the amount of information becomes enormous, therefore, optical communication, by which the required space is expected to be reduced, becomes more important. Also in the application to submarine cables, attention must be paid to the radiation resistance as there are the effects of potassium contained in large amount in seawater and uranium deposits in sea bottom. Therefore, the reliability of the components of optical communication systems against radiation becomes a problem. In this study, single mode optical fibers and transmission and receipt modules were selected, and high dose rate irradiation supposing the case of using in a cell and low dose rate, long time irradiation supposing the case of submarine cables were carried out to evaluate the radiation resistance characteristics. The fibers tested were SiO 2 core/F-SiO 2 clad type and GeO 2 -SiO 2 core/SiO 2 clad type. The characteristics of increasing loss in irradiation and restoration after irradiation of the former type were superior to those of the latter type. The output of a receipt module was normal during irradiation, and the output power of a transmission module decreases, but other problems did not arise. (K.I.)

  12. Thermal conductivity of niobium single crystals in a magnetic field

    International Nuclear Information System (INIS)

    Gladun, C.; Vinzelberg, H.

    1980-01-01

    The thermal conductivity in longitudinal magnetic fields up to 5 T and in the temperature range 3.5 to 15 K is measured in two high purity niobium single crystals having residual resistivity ratios of 22700 and 19200 and orientations of the rod axis [110] and [100]. The investigations show that by means of the longitudinal magnetic field the thermal conductivity may decrease only to a limiting value. In the crystal directions [110] and [100] for the ratio of the thermal conductivity in zero field and the thermal conductivity in the saturation field the temperature-independent factors 1.92 and 1.27, respectively, are determined. With the aid of these factors the thermal conductivity in the normal state is evaluated from the measured values of thermal conductivity below Tsub(c) in the magnetic field. The different conduction and scattering mechanisms are discussed. (author)

  13. Design optimization of the distributed modal filtering rod fiber for increasing single mode bandwidth

    DEFF Research Database (Denmark)

    Jørgensen, Mette Marie; Petersen, Sidsel Rübner; Laurila, Marko

    2012-01-01

    . Large preform tolerances are compensated during the fiber draw resulting in ultra low NA fibers with very large cores. In this paper, design optimization of the SM bandwidth of the DMF rod fiber is presented. Analysis of band gap properties results in a fourfold increase of the SM bandwidth compared...... LMA fiber amplifiers having high pump absorption through a pump cladding that is decoupled from the outer fiber. However, achieving ultra low NA for single-mode (SM) guidance is challenging, and thus different design strategies must be applied to filter out higher order modes (HOMs). The novel...... distributed modal filtering (DMF) design presented here enables SM guidance, and previous results have shown a SM mode field diameter of 60 μm operating in a 20 nm SM bandwidth. The DMF rod fiber has high index ring-shaped inclusions acting as resonators enabling SM guidance through modal filtering of HOMs...

  14. Integrated Field Analyses of Thermal Springs

    Science.gov (United States)

    Shervais, K.; Young, B.; Ponce-Zepeda, M. M.; Rosove, S.

    2011-12-01

    A group of undergraduate researchers through the SURE internship offered by the Southern California Earthquake Center (SCEC) have examined thermal springs in southern Idaho, northern Utah as well as mud volcanoes in the Salton Sea, California. We used an integrated approach to estimate the setting and maximum temperature, including water chemistry, Ipad-based image and data-base management, microbiology, and gas analyses with a modified Giggenbach sampler.All springs were characterized using GISRoam (tmCogent3D). We are performing geothermometry calculations as well as comparisons with temperature gradient data on the results while also analyzing biological samples. Analyses include water temperature, pH, electrical conductivity, and TDS measured in the field. Each sample is sealed and chilled and delivered to a water lab within 12 hours.Temperatures are continuously monitored with the use of Solinst Levelogger Juniors. Through partnership with a local community college geology club, we receive results on a monthly basis and are able to process initial data earlier in order to evaluate data over a longer time span. The springs and mudpots contained microbial organisms which were analyzed using methods of single colony isolation, polymerase chain reaction, and DNA sequencing showing the impact of the organisms on the springs or vice versa. Soon we we will collect gas samples at sites that show signs of gas. This will be taken using a hybrid of the Giggenbach method and our own methods. Drawing gas samples has proven a challenge, however we devised a method to draw out gas samples utilizing the Giggenbach flask, transferring samples to glass blood sample tubes, replacing NaOH in the Giggenbach flask, and evacuating it in the field for multiple samples using a vacuum pump. We also use a floating platform devised to carry and lower a levelogger, to using an in-line fuel filter from a tractor in order to keep mud from contaminating the equipment.The use of raster

  15. Evaluation of properties and thermal stress field for thermal barrier coatings

    Institute of Scientific and Technical Information of China (English)

    王良; 齐红宇; 杨晓光; 李旭

    2008-01-01

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

  16. New VCSEL technology with scalability for single mode operation and densely integrated arrays

    Science.gov (United States)

    Zhao, Guowei; Demir, Abdullah; Freisem, Sabine; Zhang, Yu; Liu, Xiaohang; Deppe, Dennis G.

    2011-06-01

    Data are presented demonstrating a new lithographic vertical-cavity surface-emitting laser (VCSEL) technology, which produces simultaneous mode- and current-confinement only by lithography and epitaxial crystal growth. The devices are grown by solid source molecular beam epitaxy, and have lithographically defined sizes that vary from 3 μm to 20 μm. The lithographic process allows the devices to have high uniformity throughout the wafer and scalability to very small size. The 3 μm device shows a threshold current of 310 μA, the slope efficiency of 0.81 W/A, and the maximum output power of more than 5 mW. The 3 μm device also shows single-mode single-polarization operation without the use of surface grating, and has over 25 dB side-mode-suppression-ratio up to 1 mW of output power. The devices have low thermal resistance due to the elimination of oxide aperture. High reliability is achieved by removal of internal strain caused by the oxide, stress test shows no degradation for the 3 μm device operating at very high injection current level of 142 kA/cm2 for 1000 hours, while at this dive level commercial VCSELs fail rapidly. The lithographic VCSEL technology can lead to manufacture of reliable small size laser diode, which will have application in large area 2-D arrays and low power sensors.

  17. Coherent gradient sensing method for measuring thermal stress field of thermal barrier coating structures

    Directory of Open Access Journals (Sweden)

    Kang Ma

    2017-01-01

    Full Text Available Coherent gradient sensing (CGS method can be used to measure the slope of a reflective surface, and has the merits of full-field, non-contact, and real-time measurement. In this study, the thermal stress field of thermal barrier coating (TBC structures is measured by CGS method. Two kinds of powders were sprayed onto Ni-based alloy using a plasma spraying method to obtain two groups of film–substrate specimens. The specimens were then heated with an oxy-acetylene flame. The resulting thermal mismatch between the film and substrate led to out-of-plane deformation of the specimen. The deformation was measured by the reflective CGS method and the thermal stress field of the structure was obtained through calibration with the help of finite element analysis. Both the experiment and numerical results showed that the thermal stress field of TBC structures can be successfully measured by CGS method.

  18. Mode coupling in hybrid square-rectangular lasers for single mode operation

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Xiu-Wen; Huang, Yong-Zhen, E-mail: yzhuang@semi.ac.cn; Yang, Yue-De; Xiao, Jin-Long; Weng, Hai-Zhong; Xiao, Zhi-Xiong [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100083 (China)

    2016-08-15

    Mode coupling between a square microcavity and a Fabry-Pérot (FP) cavity is proposed and demonstrated for realizing single mode lasers. The modulations of the mode Q factor as simulation results are observed and single mode operation is obtained with a side mode suppression ratio of 46 dB and a single mode fiber coupling loss of 3.2 dB for an AlGaInAs/InP hybrid laser as a 300-μm-length and 1.5-μm-wide FP cavity connected to a vertex of a 10-μm-side square microcavity. Furthermore, tunable single mode operation is demonstrated with a continuous wavelength tuning range over 10 nm. The simple hybrid structure may shed light on practical applications of whispering-gallery mode microcavities in large-scale photonic integrated circuits and optical communication and interconnection.

  19. A Single Mode Study of a Quasi-Geostrophic Convection-Driven Dynamo Model

    Science.gov (United States)

    Plumley, M.; Calkins, M. A.; Julien, K. A.; Tobias, S.

    2017-12-01

    Planetary magnetic fields are thought to be the product of hydromagnetic dynamo action. For Earth, this process occurs within the convecting, turbulent and rapidly rotating outer core, where the dynamics are characterized by low Rossby, low magnetic Prandtl and high Rayleigh numbers. Progress in studying dynamos has been limited by current computing capabilities and the difficulties in replicating the extreme values that define this setting. Asymptotic models that embrace these extreme parameter values and enforce the dominant balance of geostrophy provide an option for the study of convective flows with actual relevance to geophysics. The quasi-geostrophic dynamo model (QGDM) is a multiscale, fully-nonlinear Cartesian dynamo model that is valid in the asymptotic limit of low Rossby number. We investigate the QGDM using a simplified class of solutions that consist of a single horizontal wavenumber which enforces a horizontal structure on the solutions. This single mode study is used to explore multiscale time stepping techniques and analyze the influence of the magnetic field on convection.

  20. Amplitude Noise Suppression and Orthogonal Multiplexing Using Injection-Locked Single-Mode VCSEL

    DEFF Research Database (Denmark)

    Lyubopytov, Vladimir; von Lerber, Tuomo; Lassas, Matti

    2017-01-01

    We experimentally demonstrate BER reduction and orthogonal modulation using an injection locked single-mode VCSEL. It allows us suppressing an amplitude noise of optical signal and/or double the capacity of an information channel.......We experimentally demonstrate BER reduction and orthogonal modulation using an injection locked single-mode VCSEL. It allows us suppressing an amplitude noise of optical signal and/or double the capacity of an information channel....

  1. Refractive index sensor based on an abrupt taper Michelson interferometer in a single-mode fiber.

    Science.gov (United States)

    Tian, Zhaobing; Yam, Scott S-H; Loock, Hans-Peter

    2008-05-15

    A simple refractive index sensor based on a Michelson interferometer in a single-mode fiber is constructed and demonstrated. The sensor consists of a single symmetrically abrupt taper region in a short piece of single-mode fiber that is terminated by approximately 500 nm thick gold coating. The sensitivity of the new sensor is similar to that of a long-period-grating-type sensor, and its ease of fabrication offers a low-cost alternative to current sensing applications.

  2. Turbulent structure of thermal plume. Velocity field

    International Nuclear Information System (INIS)

    Guillou, B.; Brahimi, M.; Doan-kim-son

    1986-01-01

    An experimental investigation and a numerical study of the dynamics of a turbulent plume rising from a strongly heated source are described. This type of flow is met in thermal effluents (air, vapor) from, e.g., cooling towers of thermal power plants. The mean and fluctuating values of the vertical component of the velocity were determined using a Laser-Doppler anemometer. The measurements allow us to distinguish three regions in the plume-a developing region near the source, an intermediate region, and a self-preserving region. The characteristics of each zone have been determined. In the self-preserving zone, especially, the turbulence level on the axis and the entrainment coefficient are almost twice of the values observed in jets. The numerical model proposed takes into account an important phenomenon, the intermittency, observed in the plume. This model, established with the self-preserving hypothesis, brings out analytical laws. These laws and the predicted velocity profile are in agreement with the experimental evolutions [fr

  3. High-field EPR spectroscopy of thermal donors in silicon

    DEFF Research Database (Denmark)

    Dirksen, R.; Rasmussen, F.B.; Gregorkiewicz, T.

    1997-01-01

    Thermal donors generated in p-type boron-doped Czochralski-grown silicon by a 450 degrees C heat treatment have been studied by high-field magnetic resonance spectroscopy. In the experiments conducted at a microwave frequency of 140 GHz and in a magnetic field of approximately 5 T four individual...

  4. Hyper-thermal neutron irradiation field for neutron capture therapy

    International Nuclear Information System (INIS)

    Sakurai, Yoshinori; Kobayashi, Tooru; Kanda, Keiji

    1994-01-01

    The utilization of hyper-thermal neutrons, which have an energy spectrum of a Maxwell distribution higher than the room temperature of 300 K, has been studied in order to improve the thermal neutron flux distribution in a living body for a deep-seated tumor in neutron capture therapy (NCT). Simulation calculations using MCNP-V3 were carried out in order to investigate the characteristics of the hyper-thermal neutron irradiation field. From the results of simulation calculations, the following were confirmed: (i) The irradiation field of the hyper-thermal neutrons is feasible by using some scattering materials with high temperature, such as Be, BeO, C, SiC and ZrH 1.7 . Especially, ZrH 1.7 is thought to be the best material because of good characteristics of up-scattering for thermal neutrons. (ii) The ZrH 1.7 of 1200 K yields the hyper-thermal neutrons of a Maxwell-like distribution at about 2000 K and the treatable depth is about 1.5 cm larger comparing with the irradiation of the thermal neutrons of 300 K. (iii) The contamination by the secondary gamma-rays from the scattering materials can be sufficiently eliminated to the tolerance level for NCT through the bismuth layer, without the larger change of the energy spectrum of hyper-thermal neutrons. ((orig.))

  5. Thermomechanical fields measurement for fatigue investigation under cyclic thermal shocks

    International Nuclear Information System (INIS)

    Charbal, Ali

    2017-01-01

    Thermal fatigue occurs in nuclear power plant pipes. The temperature variations are due to the turbulent mixing of fluids that have different temperatures. Many experimental setups have been designed but the measured temperatures have only been punctual and out of the zone of interest (e.g., via thermocouples). The equivalent strain variation in the crack initiation region is calculated with numerical thermomechanical simulations. In many cases, the comparisons between numerical and experimental results have shown that the crack initiation predictions in thermal fatigue are non-conservative. a new testing setup is proposed where thermal shocks are applied with a pulsed laser beam while the thermal and kinematic fields on the specimen surface are measured with infrared (IR) and visible cameras, respectively. Experimental testings are performed and different measurement techniques for temperature and kinematic fields are used. IR camera and pyrometers allow to measure the temperature variations in the zone impacted by the laser beam. To estimate the absolute temperature, the surface emissivities at the respective wavelengths are determined by different methods. The absolute temperature field is then used to apply the actual thermal loading in a decoupled FE model after an identification process of the parameters of the laser beam. Once the thermal loading is generated based upon the experimental data, the stress and strain fields can be computed in the region of interest with an elastoplastic law.The experimental strain variations calculated from the DIC measurements are compared with the predictions obtained with the FE simulation. (author) [fr

  6. Piezoelectric transducer parameter selection for exciting a single mode from multiple modes of Lamb waves

    International Nuclear Information System (INIS)

    Zhang Hai-Yan; Yu Jian-Bo

    2011-01-01

    Excitation and propagation of Lamb waves by using rectangular and circular piezoelectric transducers surface-bonded to an isotropic plate are investigated in this work. Analytical stain wave solutions are derived for the two transducer shapes, giving the responses of these transducers in Lamb wave fields. The analytical study is supported by a numerical simulation using the finite element method. Symmetric and antisymmetric components in the wave propagation responses are inspected in detail with respect to test parameters such as the transducer geometry, the length and the excitation frequency. By placing only one piezoelectric transducer on the top or the bottom surface of the plate and weakening the strength of one mode while enhancing the strength of the other modes to find the centre frequency, with which the peak wave amplitude ratio between the S0 and A0 modes is maximum, a single mode excitation from the multiple modes of the Lamb waves can be achieved approximately. Experimental data are presented to show the validity of the analyses. The results are used to optimize the Lamb wave detection system. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  7. Computational investigation of single mode vs multimode Rayleigh endash Taylor seeding in Z-pinch implosions

    International Nuclear Information System (INIS)

    Douglas, M.R.; Deeney, C.; Roderick, N.F.

    1998-01-01

    A series of two-dimensional magnetohydrodynamic calculations have been carried out to investigate single and multimode growth and mode coupling for magnetically-driven Rayleigh endash Taylor instabilities in Z pinches. Wavelengths ranging from 5.0 mm down to 1.25 mm were considered. Such wavelengths are comparable to those observed at stagnation using a random density open-quotes seedingclose quotes method. The calculations show that wavelengths resolved by less than 10 cells exhibit an artificial decrease in initial Fourier spectrum amplitudes and a reduction in the corresponding amplitude growth. Single mode evolution exhibits linear exponential growth and the development of higher harmonics as the mode transitions into the nonlinear phase. The mode growth continues to exponentiate but at a slower rate than determined by linear hydrodynamic theory. In the two and three mode case, there is clear evidence of mode coupling and inverse cascade. In addition, distinct modal patterns are observed late in the implosion, resulting from finite shell thickness and magnetic field effects. copyright 1998 American Institute of Physics. thinsp

  8. Single Mode SU8 Polymer Based Mach-Zehnder Interferometer for Bio-Sensing Application

    Science.gov (United States)

    Boiragi, Indrajit; Kundu, Sushanta; Makkar, Roshan; Chalapathi, Krishnamurthy

    2011-10-01

    This paper explains the influence of different parameters to the sensitivity of an optical waveguide Mach-Zehnder Interferometer (MZI) for real time detection of biomolecules. The sensing principle is based on the interaction of evanescence field with the biomolecules that get immobilized on sensing arm. The sensitivity has been calculated by varying the sensing window length, wavelength and concentration of bio-analyte. The maximum attainable sensitivity for the preferred design is the order of 10-8 RIU at 840 nm wavelength with a sensing window length of 1cm. All the simulation work has been carried out with Opti-BPMCAD for the optimization of MZI device parameters. The SU8 polymers are used as a core and clad material to fabricate the waveguide. The refractive index of cladding layer is optimized by varying the curing temperature for a fixed time period and the achieved index difference between core and clad is Δn = 0.0151. The fabricated MZI device has been characterized with LASER beam profiler at 840 nm wavelength. This study demonstrates the effectiveness of the different parameter to the sensitivity of a single mode optical waveguide Mach-Zehnder Interferometer for bio-sensing application.

  9. Pulsed x-ray induced attenuation measurements of single mode optical fibers and coupler materials

    International Nuclear Information System (INIS)

    Johan, A.; Charre, P.

    1994-01-01

    Pulsed X-ray induced transient radiation attenuation measurements of single mode optical fibers have been performed versus total dose, light wavelength, optical power and fiber coil diameter in order to determine the behavior of parameters sensitive to ionizing radiation. The results did not show any photobleaching phenomenon and the attenuation was found independent of the spool diameter. As expected, transient attenuation was lower for higher wave-lengths. The recovery took place in the millisecond range and was independent of total dose, light wavelength and optical power. In optical modules and devices a large range of behaviors was observed according to coupler material i.e., Corning coupler showed a small peak attenuation that remained more than one day later; on the other hand LiTaO 3 material experienced an order of magnitude higher peak attenuation and a recovery in the millisecond range. For applications with optical fibers and integrated optics devices the authors showed that in many cases the optical fiber (length above 100 m) is the most sensitive device in a transient ionizing radiation field

  10. Impact of quantum–classical correspondence on entanglement enhancement by single-mode squeezing

    International Nuclear Information System (INIS)

    Joseph, Sijo K.; Chew, Lock Yue; Sanjuán, Miguel A.F.

    2014-01-01

    Quantum entanglement between two field modes can be achieved through the collective squeezing of the two respective modes. If single-mode squeezing is performed prior to such a two-mode squeezing, an enhancement of entanglement production can happen. Interestingly, the occurrence of this enhancement can be implicitly linked to the local classical dynamical behavior via the paradigm of quantum–classical correspondence. In particular, the entanglement generated through quantum chaos is found to be hardly enhanced by prior squeezing, since it is bounded by the saturation value of the maximally entangled Schmidt state with fixed energy. These results illustrate that entanglement enhancement via initial squeezing can serve as a useful indicator of quantum chaotic behaviour. - Highlights: • Continuous-variable entanglement is explored in the Pullen–Edmonds Hamiltonian. • The local phase-space structure and the entanglement enhancement are related. • Entanglement enhancement via squeezing is smaller for the chaotic orbit. • Entanglement enhancement via squeezing is higher for the regular orbit. • The magnitude of the entanglement enhancement serves as a quantum-chaos indicator

  11. Thermal quantum discord of spins in an inhomogeneous magnetic field

    International Nuclear Information System (INIS)

    Guo Jinliang; Mi Yingjuan; Zhang Jian; Song Heshan

    2011-01-01

    In contrast with the thermal entanglement, we study the quantum discord and classical correlation in a two-qubit Heisenberg XXZ model with an inhomogeneous magnetic field. It is shown that the effects of the external magnetic fields, including the uniform and inhomogeneous magnetic fields, on the thermal entanglement, quantum discord and classical correlation behave differently in various aspects, which depend on system temperature and model type. We can tune the inhomogeneous magnetic field to enhance the entanglement or classical correlation and meanwhile decrease the quantum discord. In addition, taking into account the inhomogeneous magnetic field, the sudden change in the behaviour of quantum discord still survives, which can detect the critical points of quantum phase transitions at finite temperature, but not for a uniform magnetic field.

  12. Modeling bidirectionally coupled single-mode semiconductor lasers

    International Nuclear Information System (INIS)

    Mulet, Josep; Masoller, Cristina; Mirasso, Claudio R.

    2002-01-01

    We develop a dynamical model suitable for the description of two mutually coupled semiconductor lasers in a face-to-face configuration. Our study considers the propagation of the electric field along the compound system as well as the evolution of the carrier densities within each semiconductor laser. Mutual injection, passive optical feedback, and multiple reflections are accounted for in this framework, although under weak to moderate coupling conditions. We systematically describe the effect of the coupling strength on the spectrum of monochromatic solutions and on the respective dynamical behavior. By assuming single-longitudinal-mode operation, weak mutual coupling and slowly varying approximation, the dynamical model can be reduced to rate equations describing the mutual injection from one laser to its counterpart and vice versa. A good agreement between the complete and simplified models is found for small coupling. For larger coupling, higher-order terms lead to a smaller threshold reduction, reflected itself in the spectrum of the monochromatic solutions and in the dynamics of the optical power

  13. Single-mode glass waveguide technology for optical interchip communication on board level

    Science.gov (United States)

    Brusberg, Lars; Neitz, Marcel; Schröder, Henning

    2012-01-01

    The large bandwidth demand in long-distance telecom networks lead to single-mode fiber interconnects as result of low dispersion, low loss and dense wavelength multiplexing possibilities. In contrast, multi-mode interconnects are suitable for much shorter lengths up to 300 meters and are promising for optical links between racks and on board level. Active optical cables based on multi-mode fiber links are at the market and research in multi-mode waveguide integration on board level is still going on. Compared to multi-mode, a single-mode waveguide has much more integration potential because of core diameters of around 20% of a multi-mode waveguide by a much larger bandwidth. But light coupling in single-mode waveguides is much more challenging because of lower coupling tolerances. Together with the silicon photonics technology, a single-mode waveguide technology on board-level will be the straight forward development goal for chip-to-chip optical interconnects integration. Such a hybrid packaging platform providing 3D optical single-mode links bridges the gap between novel photonic integrated circuits and the glass fiber based long-distance telecom networks. Following we introduce our 3D photonic packaging approach based on thin glass substrates with planar integrated optical single-mode waveguides for fiber-to-chip and chip-to-chip interconnects. This novel packaging approach merges micro-system packaging and glass integrated optics. It consists of a thin glass substrate with planar integrated singlemode waveguide circuits, optical mirrors and lenses providing an integration platform for photonic IC assembly and optical fiber interconnect. Thin glass is commercially available in panel and wafer formats and characterizes excellent optical and high-frequency properties. That makes it perfect for microsystem packaging. The paper presents recent results in single-mode waveguide technology on wafer level and waveguide characterization. Furthermore the integration in a

  14. Information loss in effective field theory: Entanglement and thermal entropies

    Science.gov (United States)

    Boyanovsky, Daniel

    2018-03-01

    Integrating out high energy degrees of freedom to yield a low energy effective field theory leads to a loss of information with a concomitant increase in entropy. We obtain the effective field theory of a light scalar field interacting with heavy fields after tracing out the heavy degrees of freedom from the time evolved density matrix. The initial density matrix describes the light field in its ground state and the heavy fields in equilibrium at a common temperature T . For T =0 , we obtain the reduced density matrix in a perturbative expansion; it reveals an emergent mixed state as a consequence of the entanglement between light and heavy fields. We obtain the effective action that determines the time evolution of the reduced density matrix for the light field in a nonperturbative Dyson resummation of one-loop correlations of the heavy fields. The Von-Neumann entanglement entropy associated with the reduced density matrix is obtained for the nonresonant and resonant cases in the asymptotic long time limit. In the nonresonant case the reduced density matrix displays an incipient thermalization albeit with a wave-vector, time and coupling dependent effective temperature as a consequence of memory of initial conditions. The entanglement entropy is time independent and is the thermal entropy for this effective, nonequilibrium temperature. In the resonant case the light field fully thermalizes with the heavy fields, the reduced density matrix loses memory of the initial conditions and the entanglement entropy becomes the thermal entropy of the light field. We discuss the relation between the entanglement entropy ultraviolet divergences and renormalization.

  15. Characteristics of thermal neutron calibration fields using a graphite pile

    International Nuclear Information System (INIS)

    Uchita, Yoshiaki; Saegusa, Jun; Kajimoto, Yoichi; Tanimura, Yoshihiko; Shimizu, Shigeru; Yoshizawa, Michio

    2005-03-01

    The Facility of Radiation Standards of Japan Atomic Energy Research Institute is equipped with thermal neutron fields for calibrating area and personal neutron dosemeters. The fields use moderated neutrons leaked from a graphite pile in which radionuclide sources are placed. In January 2003, we have renewed the pile with some modifications in its size. In accordance with the renewal, we measured and calculated thermal neutron fluence rates, neutron energy distributions and angular distributions of the fields. The thermal neutron fluence rates of the ''inside-pile fields'' and the outside-pile fields'' were determined by the gold foil activation method. The neutron energy distributions of the outside-pile fields were also measured with the Bonner multi-sphere spectrometer system. The contributions of epithermal and fast neutrons to the total dose-equivalents were 9% in the southern outside-pile field and 12% in the western outside-pile field. The personal dose-equivalents, H p,slab (10, α), in the outside-pile fields are evaluated by considering the calculated angular distributions of incoming neutrons. The H p,slab (10, α) was found to be about 40% higher than the value in assuming the unidirectional neutron between the pile and the test point. (author)

  16. Thermal and superthermal properties of supersymmetric field theories

    International Nuclear Information System (INIS)

    Fuchs, J.

    1984-01-01

    We discuss the finite-temperature behaviour of supersymmetric field theories. We show that their 'superthermal' properties which concern the question of susy breaking at finite temperature and their thermal properties must be considered separately. Susy breaking is determined by the so-called superthermal ensemble, whereas thermodynamical properties follow from the conventional thermal ensemble, leading to the usual statistics for the bosonic and fermionic components of a superfield. We show that superspace techniques can be used in a straightforward way only for superthermal Green functions but not for thermal ones. We also discuss the possibility of finite-temperature susy restoration and the implications of Goldstone's theorem at finite temperature. (orig.)

  17. Facile synthesis of graphene on single mode fiber via chemical vapor deposition

    International Nuclear Information System (INIS)

    Zhang, C.; Man, B.Y.; Jiang, S.Z.; Yang, C.; Liu, M.; Chen, C.S.; Xu, S.C.; Feng, D.J.; Bi, D.; Liu, F.Y.; Qiu, H.W.

    2014-01-01

    Direct deposition of graphene film on the standard single mode fiber is offered using a Cu-vapor-assisted chemical vapor deposition system. The gas flow of H 2 and Ar before the growth process plays a crucial role for the direct deposition of the graphene film and the layers of the graphene can be controlled by the growth time. With a large gas flow, Cu atoms are carried off with the gas flow and hard to deposit on the surface of the single mode fiber before the growth process. Consequently, uniform graphene film is obtained in this case. On the contrary, with a lower one, Cu atoms is facile to deposit on the surface of the single mode fiber and form nanodots acting as active catalytic sites for the growth of carbon nanotubes. This method presents us a promising transfer-free technique for fabrication of the photonic applications.

  18. Pretest Calculations of Temperature Changes for Field Thermal Conductivity Tests

    International Nuclear Information System (INIS)

    N.S. Brodsky

    2002-01-01

    A large volume fraction of the potential monitored geologic repository at Yucca Mountain may reside in the Tptpll (Tertiary, Paintbrush Group, Topopah Spring Tuff, crystal poor, lower lithophysal) lithostratigraphic unit. This unit is characterized by voids, or lithophysae, which range in size from centimeters to meters. A series of thermal conductivity field tests are planned in the Enhanced Characterization of the Repository Block (ECRB) Cross Drift. The objective of the pretest calculation described in this document is to predict changes in temperatures in the surrounding rock for these tests for a given heater power and a set of thermal transport properties. The calculation can be extended, as described in this document, to obtain thermal conductivity, thermal capacitance (density x heat capacity, J · m -3 · K -1 ), and thermal diffusivity from the field data. The work has been conducted under the ''Technical Work Plan For: Testing and Monitoring'' (BSC 2001). One of the outcomes of this analysis is to determine the initial output of the heater. This heater output must be sufficiently high that it will provide results in a reasonably short period of time (within several weeks or a month) and be sufficiently high that the heat increase is detectable by the instruments employed in the test. The test will be conducted in stages and heater output will be step increased as the test progresses. If the initial temperature is set too high, the experiment will not have as many steps and thus fewer thermal conductivity data points will result

  19. The deep thermal field of the Upper Rhine Graben

    Science.gov (United States)

    Freymark, Jessica; Sippel, Judith; Scheck-Wenderoth, Magdalena; Bär, Kristian; Stiller, Manfred; Fritsche, Johann-Gerhard; Kracht, Matthias

    2017-01-01

    The Upper Rhine Graben has a significant socioeconomic relevance as it provides a great potential for geothermal energy production. The key for the utilisation of this energy resource is to understand the controlling factors of the thermal field in this area. We have therefore built a data-based lithospheric-scale 3D structural model of the Upper Rhine Graben and its adjacent areas. In addition, 3D gravity modelling was performed to constrain the internal structure of the crystalline crust consistent with seismic information. Based on this lithosphere scale 3D structural model the present-day conductive thermal field was calculated and compared to measured temperatures. Our results show that the regional thermal field is mainly controlled by the configuration of the upper crust, which has different thermal properties characteristic for the Variscan and Alpine domains. Temperature maxima are predicted for the Upper Rhine Graben where thick insulating Cenozoic sediments cause a thermal blanketing effect and where the underlying crustal units are characterised by high radiogenic heat production. The comparison of calculated and measured temperatures overall shows a reasonable fit, while locally occuring model deviations indicate where a larger influence of groundwater flow may be expected.

  20. Physics of reshock and mixing in single-mode Richtmyer-Meshkov instability

    International Nuclear Information System (INIS)

    Schilling, O; Latini, M; Don, W

    2006-01-01

    The ninth-order weighted essentially non-oscillatory (WENO) shock-capturing method is used to investigate the physics of reshock and mixing in two-dimensional single-mode Richtmyer-Meshkov instability to late times. The initial conditions and computational domain were adapted from the Mach 1.21 air(acetone)/SF 6 shock tube experiment of Collins and Jacobs [J. Fluid Mech. 464, 113 (2002)]: the growth of the bubble and spike perturbation amplitudes from fifth- and ninth-order WENO simulations of this experiment were compared to the predictions of amplitude growth models, and were shown to be in very good agreement with the experimental data prior to reshock [Latini, Schilling and Don, Phys. Fluids (2007), in press]. In the present investigation, the density, vorticity, baroclinic vorticity production, and simulated density Schlieren fields are first presented to qualitatively describe reshock. The baroclinic circulation deposition on the interface is shown to agree with the predictions of the Samtaney and Zabusky [J. Fluid Mech. 269, 45 (1994)] model and linear instability theory. The time-evolution of the positive and negative circulation on the interface is considered before and after reshock: it is shown that the circulations are equal before, as well as after reshock, until the interaction of the reflected rarefaction with the layer leads to flow symmetry breaking and different evolutions of the positive and negative circulation. The post-reshock mixing layer growth is shown to be in very good agreement with three models predicting linear growth for a short time following reshock. Next, a comprehensive investigation of local and global mixing properties as a function of time is performed. The distribution and amount of mixed fluid along the shock propagation direction is characterized using averaged mole fraction profiles, a fast kinetic reaction model, and molecular mixing fractions. The modal distribution of energy in the mixing layer is quantified using the

  1. A New Three-Dimensional High-Accuracy Automatic Alignment System For Single-Mode Fibers

    Science.gov (United States)

    Yun-jiang, Rao; Shang-lian, Huang; Ping, Li; Yu-mei, Wen; Jun, Tang

    1990-02-01

    In order to achieve the low-loss splices of single-mode fibers, a new three-dimension high-accuracy automatic alignment system for single -mode fibers has been developed, which includes a new-type three-dimension high-resolution microdisplacement servo stage driven by piezoelectric elements, a new high-accuracy measurement system for the misalignment error of the fiber core-axis, and a special single chip microcomputer processing system. The experimental results show that alignment accuracy of ±0.1 pin with a movable stroke of -±20μm has been obtained. This new system has more advantages than that reported.

  2. Single-mode fiber laser based on core-cladding mode conversion.

    Science.gov (United States)

    Suzuki, Shigeru; Schülzgen, Axel; Peyghambarian, N

    2008-02-15

    A single-mode fiber laser based on an intracavity core-cladding mode conversion is demonstrated. The fiber laser consists of an Er-doped active fiber and two fiber Bragg gratings. One Bragg grating is a core-cladding mode converter, and the other Bragg grating is a narrowband high reflector that selects the lasing wavelength. Coupling a single core mode and a single cladding mode by the grating mode converter, the laser operates as a hybrid single-mode laser. This approach for designing a laser cavity provides a much larger mode area than conventional large-mode-area step-index fibers.

  3. Cross-correlated imaging of single-mode photonic crystal rod fiber with distributed mode filtering

    DEFF Research Database (Denmark)

    Laurila, Marko; Barankov, Roman; Jørgensen, Mette Marie

    2013-01-01

    Photonic crystal bandgap fibers employing distributed mode filtering design provide near diffraction-limited light outputs, a critical property of fiber-based high-power lasers. Microstructure of the fibers is tailored to achieve single-mode operation at specific wavelength by resonant mode...... identify regimes of resonant coupling between higher-order core modes and cladding band. We demonstrate a passive fiber design in which the higher-order modal content inside the single-mode guiding regime is suppressed by at least 20 dB even for significantly misaligned input-coupling configurations....

  4. Large-core single-mode rib SU8 waveguide using solvent-assisted microcontact molding.

    Science.gov (United States)

    Huang, Cheng-Sheng; Wang, Wei-Chih

    2008-09-01

    This paper describes a novel fabrication technique for constructing a polymer-based large-core single-mode rib waveguide. A negative tone SU8 photoresist with a high optical transmission over a large wavelength range and stable mechanical properties was used as a waveguide material. A waveguide was constructed by using a polydimethylsiloxane stamp combined with a solvent-assisted microcontact molding technique. The effects on the final pattern's geometry of four different process conditions were investigated. Optical simulations were performed using beam propagation method software. Single-mode beam propagation was observed at the output of the simulated waveguide as well as the actual waveguide through the microscope image.

  5. Single mode operation of a hybrid optically pumped D2O far infrared laser

    International Nuclear Information System (INIS)

    Yuan, D.C.; Siegrist, M.R.

    1990-04-01

    We have achieved single mode operation in a hybrid optically pumped D 2 O far infrared laser. The active volume of the resonator was divided into two sections separated by a thin plastic foil. The larger section served as the main gain medium and the shorter section as mode selective element. The vapor pressure in the smaller volume was either very low or alternatively about 3 times higher than the pressure in the main part. In both cases single mode operation was achieved without any reduction of the total output energy. (author) 13 refs., 7 figs

  6. Second-order interference of two independent and tunable single-mode continuous-wave lasers

    International Nuclear Information System (INIS)

    Liu Jianbin; Chen Hui; Zheng Huaibin; Xu Zhuo; Wei Dong; Zhou Yu; Gao Hong; Li Fu-Li

    2016-01-01

    The second-order temporal interference of two independent single-mode continuous-wave lasers is discussed by employing two-photon interference in Feynman’s path integral theory. It is concluded that whether the second-order temporal interference pattern can or cannot be retrieved via two-photon coincidence counting rate is dependent on the resolution time of the detection system and the frequency difference between these two lasers. Two identical and tunable single-mode continuous-wave diode lasers are employed to verify the predictions. These studies are helpful to understand the physics of two-photon interference with photons of different spectra. (paper)

  7. The second-order interference of two independent single-mode He-Ne lasers

    Science.gov (United States)

    Liu, Jianbin; Le, Mingnan; Bai, Bin; Wang, Wentao; Chen, Hui; Zhou, Yu; Li, Fu-li; Xu, Zhuo

    2015-09-01

    The second-order spatial and temporal interference patterns with two independent single-mode continuous-wave He-Ne lasers are observed when these two lasers are incident to two adjacent input ports of a 1:1 non-polarizing beam splitter, respectively. Two-photon interference based on the superposition principle in Feynman's path integral theory is employed to interpret the experimental results. The conditions to observe the second-order interference pattern with two independent single-mode continuous-wave lasers are discussed. It is concluded that frequency stability is important to observe the second-order interference pattern with two independent light beams.

  8. Design of all solid state tunable single-mode Ti: sapphire laser for nuclear industry

    International Nuclear Information System (INIS)

    Lee, J.H.; Nam, S.M.; Lee, Y.J.; Lee, J.M.; Horn, Roland E.; Wendt, Klaus

    1999-01-01

    We designed a Ti:Sapphire laser pumped by a diode laser pumped solid state laser (DPSSL). The DPSSL was intra-cavity frequency doubled and it had 20 W output power. The Ti:Sapphire laser was designed for single longitudinal mode lasing. For single mode lasing, the laser used several solid etalons. We simulated temporal evolution of the laser pulse and single pass amplification rate of the photons in each modes from rate equations. From the result, we found that single mode lasing is viable in this cavity

  9. Factors affecting particle retention in thermal field-flow fractionation

    African Journals Online (AJOL)

    colloidal material is illustrated through the evaluation of thermal diffusion coefficient of PS ... Field-flow fractionation (FFF) is a separation method introduced by Giddings in 1966 [1]. It is a ... no stationary phase is used in FFF. .... that the inversion diameter (diameter at which order of retention changes) can be shifted up or.

  10. factors affecting particle retention in thermal field-flow fractionation

    African Journals Online (AJOL)

    In this paper, we report a range of factors which affect the retention of colloidal particles in thermal field-flow fractionation (ThFFF). These results are observed among different sizes of polystyrene (PS) latex particles suspended in both aqueous and nonaqueous liquid carriers and very low density lipoproteins in a phosphate ...

  11. Model of a single mode energy harvester and properties for optimal power generation

    International Nuclear Information System (INIS)

    Liao Yabin; Sodano, Henry A

    2008-01-01

    The process of acquiring the energy surrounding a system and converting it into usable electrical energy is termed power harvesting. In the last few years, the field of power harvesting has experienced significant growth due to the ever increasing desire to produce portable and wireless electronics with extended life. Current portable and wireless devices must be designed to include electrochemical batteries as the power source. The use of batteries can be troublesome due to their finite energy supply, which necessitates their periodic replacement. In the case of wireless sensors that are to be placed in remote locations, the sensor must be easily accessible or of disposable nature to allow the device to function over extended periods of time. Energy scavenging devices are designed to capture the ambient energy surrounding the electronics and covert it into usable electrical energy. The concept of power harvesting works towards developing self-powered devices that do not require replaceable power supplies. The development of energy harvesting systems is greatly facilitated by an accurate model to assist in the design of the system. This paper will describe a theoretical model of a piezoelectric based energy harvesting system that is simple to apply yet provides an accurate prediction of the power generated around a single mode of vibration. Furthermore, this model will allow optimization of system parameters to be studied such that maximal performance can be achieved. Using this model an expression for the optimal resistance and a parameter describing the energy harvesting efficiency will be presented and evaluated through numerical simulations. The second part of this paper will present an experimental validation of the model and optimal parameters

  12. Near-Field Thermal Radiation for Solar Thermophotovoltaics and High Temperature Thermal Logic and Memory Applications

    Science.gov (United States)

    Elzouka, Mahmoud

    This dissertation investigates Near-Field Thermal Radiation (NFTR) applied to MEMS-based concentrated solar thermophotovoltaics (STPV) energy conversion and thermal memory and logics. NFTR is the exchange of thermal radiation energy at nano/microscale; when separation between the hot and cold objects is less than dominant radiation wavelength (˜1 mum). NFTR is particularly of interest to the above applications due to its high rate of energy transfer, exceeding the blackbody limit by orders of magnitude, and its strong dependence on separation gap size, surface nano/microstructure and material properties. Concentrated STPV system converts solar radiation to electricity using heat as an intermediary through a thermally coupled absorber/emitter, which causes STPV to have one of the highest solar-to-electricity conversion efficiency limits (85.4%). Modeling of a near-field concentrated STPV microsystem is carried out to investigate the use of STPV based solid-state energy conversion as high power density MEMS power generator. Numerical results for In 0.18Ga0.82Sb PV cell illuminated with tungsten emitter showed significant enhancement in energy transfer, resulting in output power densities as high as 60 W/cm2; 30 times higher than the equivalent far-field power density. On thermal computing, this dissertation demonstrates near-field heat transfer enabled high temperature NanoThermoMechanical memory and logics. Unlike electronics, NanoThermoMechanical memory and logic devices use heat instead of electricity to record and process data; hence they can operate in harsh environments where electronics typically fail. NanoThermoMechanical devices achieve memory and thermal rectification functions through the coupling of near-field thermal radiation and thermal expansion in microstructures, resulting in nonlinear heat transfer between two temperature terminals. Numerical modeling of a conceptual NanoThermoMechanical is carried out; results include the dynamic response under

  13. Probe branes thermalization in external electric and magnetic fields

    International Nuclear Information System (INIS)

    Ali-Akbari, M.; Ebrahim, H.; Rezaei, Z.

    2014-01-01

    We study thermalization on rotating probe branes in AdS 5 ×S 5 background in the presence of constant external electric and magnetic fields. In the AdS/CFT framework this corresponds to thermalization in the flavour sector in field theory. The horizon appears on the worldvolume of the probe brane due to its rotation in one of the sphere directions. For both electric and magnetic fields the behaviour of the temperature is independent of the probe brane dimension. We also study the open string metric and the fluctuations of the probe brane in such a set-up. We show that the temperatures obtained from open string metric and observed by the fluctuations are larger than the one calculated from the induced metric

  14. Entropy for the Quantized Field in the Atom-Field Interaction: Initial Thermal Distribution

    Directory of Open Access Journals (Sweden)

    Luis Amilca Andrade-Morales

    2016-09-01

    Full Text Available We study the entropy of a quantized field in interaction with a two-level atom (in a pure state when the field is initially in a mixture of two number states. We then generalise the result for a thermal state; i.e., an (infinite statistical mixture of number states. We show that for some specific interaction times, the atom passes its purity to the field and therefore the field entropy decreases from its initial value.

  15. Finite-size fluctuations and photon statistics near the polariton condensation transition in a single-mode microcavity

    International Nuclear Information System (INIS)

    Eastham, P. R.; Littlewood, P. B.

    2006-01-01

    We consider polariton condensation in a generalized Dicke model, describing a single-mode cavity containing quantum dots, and extend our previous mean-field theory to allow for finite-size fluctuations. Within the fluctuation-dominated regime the correlation functions differ from their (trivial) mean-field values. We argue that the low-energy physics of the model, which determines the photon statistics in this fluctuation-dominated crossover regime, is that of the (quantum) anharmonic oscillator. The photon statistics at the crossover are different in the high-temperature and low-temperature limits. When the temperature is high enough for quantum effects to be neglected we recover behavior similar to that of a conventional laser. At low enough temperatures, however, we find qualitatively different behavior due to quantum effects

  16. Multi-level single mode 2D polymer waveguide optical interconnects using nano-imprint lithography

    NARCIS (Netherlands)

    Khan, M.U.; Justice, J.; Petäjä, J.; Korhonen, T.; Boersma, A.; Wiegersma, S.; Karppinen, M.; Corbett, B.

    2015-01-01

    Single and multi-layer passive optical interconnects using single mode polymer waveguides are demonstrated using UV nano-imprint lithography. The fabrication tolerances associated with imprint lithography are investigated and we show a way to experimentally quantify a small variation in index

  17. Flexible long-range surface plasmon polariton single-mode waveguide for optical interconnects

    DEFF Research Database (Denmark)

    Vernoux, Christian; Chen, Yiting; Markey, Laurent

    2018-01-01

    We present the design, fabrication and characterization of long-range surface plasmon polariton waveguide arrays with materials, mainly silicones, carefully selected with the aim to be used as mechanically flexible single-mode optical interconnections, the socalled "plasmonic arc" working at 1.55μm...

  18. Adapting the mode profile of planar waveguides to single-mode fibers : a novel method

    NARCIS (Netherlands)

    Smit, M.K.; Vreede, De A.H.

    1991-01-01

    A novel method for coupling single-mode fibers to planar optical circuits with small waveguide dimensions is proposed. The method eliminates the need to apply microoptics or to adapt the waveguide dimensions within the planar circuit to the fiber dimensions. Alignment tolerances are comparable to

  19. Development of IR single mode optical fibers for DARWIN-nulling interferometry

    NARCIS (Netherlands)

    Chakkalakkal Abdulla, S.M.; Cheng, L.K.; Bosch, B. van den; Dijkhuizen, N.; Nieuwland, R.A.; Gielesen, W.L.M.; Lucas, J.; Boussard-Plédel, C.; Conseil, C.; Bureau, B.; Carmo, J.P. do

    2014-01-01

    The DARWIN mission aims to detect weak infra-red emission lines from distant orbiting earth-like planets using nulling interferometry. This requires filtering of wavefront errors using single mode waveguides operating at a wavelength range of 6.5-20 μm. This article describes the optical design of

  20. Low-loss single-mode hollow-core fiber with anisotropic anti-resonant elements

    DEFF Research Database (Denmark)

    Habib, Selim; Bang, Ole; Bache, Morten

    2016-01-01

    A hollow-core fiber using anisotropic anti-resonant tubes in thecladding is proposed for low loss and effectively single-mode guidance. We show that the loss performance and higher-order mode suppression is significantly improved by using symmetrically distributed anisotropic antiresonant tubes i...

  1. Extremely low-loss single-mode photonic crystal fiber in the terahertz regime

    DEFF Research Database (Denmark)

    Islam, Raonaqul; Hasanuzzaman, G. K M; Sadath, Md Anwar

    2015-01-01

    This paper presents an updated design and numerical characterization of a rotated porous-core hexagonal photonic crystal fiber (PCF) for single-mode terahertz (THz) wave guidance. The simulation results are found using an efficient finite element method (FEM) which show a better and ultra-low eff...

  2. Single-mode 37-core fiber with a cladding diameter of 248 μm

    DEFF Research Database (Denmark)

    Sasaki, Y.; Takenaga, K.; Aikawa, K.

    2017-01-01

    A heterogeneous single-mode 37-core fiber with a cladding diameter of 248 μm is designed and fabricated. The fiber provides the highest core count and low total-crosstalk less than −20 dB/1000 km in C+L band....

  3. Mixed Field Modification of Thermally Cured Castor Oil Based Polyurethanes

    International Nuclear Information System (INIS)

    Mortley, A.

    2006-01-01

    Thermally cured polyurethanes were prepared from castor oil and hexamethylene diisocyanatee (HMDI). Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were subjected to a range of accumulated doses (0.0-3.0 MGy) produced by the mixed ionizing field of the SLOWPOKE-2 research reactor. The physico-mechanical properties of COPU, unirradiated and irradiated, were characterized by mechanical tests. Increased bond formation resulting from radiation-induced crosslinking was confirmed by favorable increases in mechanical properties and by solid-state 13 C -NMR and FTIR spectra

  4. Single Mode Fiber Optic Transceiver Using Short Wavelength Active Devices In Long Wavelength Fiber

    Science.gov (United States)

    Gillham, Frederick J.; Campbell, Daniel R.; Corke, Michael; Stowe, David W.

    1990-01-01

    Presently, single mode optical fiber technology is being utilized in systems to supply telephone service to the subscriber. However, in an attempt to be competitive with copper based systems, there are many development programs underway to determine the most cost effective solution while still providing a service that will either satisfy or be upgradeable to satisfy the demands of the consumer for the next 10 to 20 years. One such approach is to combine low cost laser transmitters and silicon receivers, which have been developed for the "compact disc" industry, with fiber that operates in the single mode regime at 1300 nm. In this paper, an optical transceiver will be presented, consisting of a compact disc laser, a silicon detector and a single mode coupler at 1300 nm. A possible system layout is presented which operates at 780 nm bi-directionally for POTS and upgradeable to 1300 nm for video services. There are several important design criteria that have to be considered in the development of such a system which will be addressed. These include: 1. Optimization of coupled power from laser to fiber while maintaining stable launched conditions over a wide range of environmental conditions. 2. Consideration of the multimode operation of the 1300 nm single mode fiber while operating in the 780 nm wavelength region. 3. Development of a low cost pseudo-wavelength division multiplexer for 1300 nm single mode/780 nm multimode operation and a low cost dual mode 50/50, 780 nm splitter using 1300 nm fiber. Details will be given of the design criteria and solution in terms of optimized design. Results of the performance of several prototype devices will be given with indications of the merits of this approach and where further development effort should be applied.

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

    International Nuclear Information System (INIS)

    Schubert, G.; Ross, M.N.; Stevenson, D.J.; Spohn, T.

    1988-01-01

    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

  6. Quantum fields on manifolds: PCT and gravitationally induced thermal states

    International Nuclear Information System (INIS)

    Sewell, G.L.

    1982-01-01

    We formulate an axiomatic scheme, designed to provide a framework for a general, rigorous theory of relativistic quantum fields on a class of manifolds, that includes Kruskal's extension of Schwarzchild space-time, as well as Minkowski space-time. The scheme is an adaptation of Wightman's to this class of manifolds. We infer from it that, given an arbitrary field (in general, interacting) on a manifold X, the restriction of the field to a certain open submanifold X/sup( + ), whose boundaries are event horizons, satisfies the Kubo--Martin--Schwinger (KMS) thermal equilibrium conditions. This amounts to a rigorous, model-independent proof of a generalized Hawking--Unruh effect. Further, in cases where the field enjoys a certain PCT symmetry, the conjugation governing the KMS condition is just the PCT operator. The key to these results is an analogue, that we prove, of the Bisognano--Wichmann theorem [J. Math. Phys. 17, (1976), Theorem 1]. We also construct an alternative scheme by replacing a regularity condition at an event horizon by the assumption that the field in X/sup( + ) is in a ground, rather then a thermal, state. We show that, in this case, the observables in X/sup( + ) are uncorrelated to those in its causal complement, X/sup( - ), and thus that the event horizons act as physical barriers. Finally, we argue that the choice between the two schemes must be dictated by the prevailing conditions governing the state of the field

  7. Zero field reversal probability in thermally assisted magnetization reversal

    Science.gov (United States)

    Prasetya, E. B.; Utari; Purnama, B.

    2017-11-01

    This paper discussed about zero field reversal probability in thermally assisted magnetization reversal (TAMR). Appearance of reversal probability in zero field investigated through micromagnetic simulation by solving stochastic Landau-Lifshitz-Gibert (LLG). The perpendicularly anisotropy magnetic dot of 50×50×20 nm3 is considered as single cell magnetic storage of magnetic random acces memory (MRAM). Thermally assisted magnetization reversal was performed by cooling writing process from near/almost Curie point to room temperature on 20 times runs for different randomly magnetized state. The results show that the probability reversal under zero magnetic field decreased with the increase of the energy barrier. The zero-field probability switching of 55% attained for energy barrier of 60 k B T and the reversal probability become zero noted at energy barrier of 2348 k B T. The higest zero-field switching probability of 55% attained for energy barrier of 60 k B T which corespond to magnetif field of 150 Oe for switching.

  8. Compton scattering at finite temperature: thermal field dynamics approach

    International Nuclear Information System (INIS)

    Juraev, F.I.

    2006-01-01

    Full text: Compton scattering is a classical problem of quantum electrodynamics and has been studied in its early beginnings. Perturbation theory and Feynman diagram technique enables comprehensive analysis of this problem on the basis of which famous Klein-Nishina formula is obtained [1, 2]. In this work this problem is extended to the case of finite temperature. Finite-temperature effects in Compton scattering is of practical importance for various processes in relativistic thermal plasmas in astrophysics. Recently Compton effect have been explored using closed-time path formalism with temperature corrections estimated [3]. It was found that the thermal cross section can be larger than that for zero-temperature by several orders of magnitude for the high temperature realistic in astrophysics [3]. In our work we use a main tool to account finite-temperature effects, a real-time finite-temperature quantum field theory, so-called thermofield dynamics [4, 5]. Thermofield dynamics is a canonical formalism to explore field-theoretical processes at finite temperature. It consists of two steps, doubling of Fock space and Bogolyubov transformations. Doubling leads to appearing additional degrees of freedom, called tilded operators which together with usual field operators create so-called thermal doublet. Bogolyubov transformations make field operators temperature-dependent. Using this formalism we treat Compton scattering at finite temperature via replacing in transition amplitude zero-temperature propagators by finite-temperature ones. As a result finite-temperature extension of the Klein-Nishina formula is obtained in which differential cross section is represented as a sum of zero-temperature cross section and finite-temperature correction. The obtained result could be useful in quantum electrodynamics of lasers and for relativistic thermal plasma processes in astrophysics where correct account of finite-temperature effects is important. (author)

  9. Workshop on Thermal Field Theory to Neural Networks

    CERN Document Server

    Veneziano, Gabriele; Aurenche, Patrick

    1996-01-01

    Tanguy Altherr was a Fellow in the Theory Division at CERN, on leave from LAPP (CNRS) Annecy. At the time of his accidental death in July 1994, he was only 31.A meeting was organized at CERN, covering the various aspects of his scientific interests: thermal field theory and its applications to hot or dense media, neural networks and its applications to high energy data analysis. Speakers were among his closest collaborators and friends.

  10. Hot gauge field properties from the thermal variational principle

    International Nuclear Information System (INIS)

    Schroeder, Y.; Schulz, H.

    1995-10-01

    A Feynman-Jensen version of the thermal variational principle is applied to hot gauge fields, abelian as well as nonabelian: scalar electrodynamics (without scalar self-coupling) and the gluon plasma. The perturbatively known self-energies are shown to derive by variation from a free quadratic (''gaussian'') trial Lagrangian. Independence of the covariant gauge fixing parameter is reached (within the order g 2 studies and for scalar ED) after a reformulation of the partition function such that it depends on only even powers of the gauge field. This way, however, the potential non-perturbative power of the calculus seems to be ruined. (orig.)

  11. Magnetic field approaches in dc thermal plasma modelling

    International Nuclear Information System (INIS)

    Freton, P; Gonzalez, J J; Masquere, M; Reichert, Frank

    2011-01-01

    The self-induced magnetic field has an important role in thermal plasma configurations generated by electric arcs as it generates velocity through Lorentz forces. In the models a good representation of the magnetic field is thus necessary. Several approaches exist to calculate the self-induced magnetic field such as the Maxwell-Ampere formulation, the vector potential approach combined with different kinds of boundary conditions or the Biot and Savart (B and S) formulation. The calculation of the self-induced magnetic field is alone a difficult problem and only few papers of the thermal plasma community speak on this subject. In this study different approaches with different boundary conditions are applied on two geometries to compare the methods and their limitations. The calculation time is also one of the criteria for the choice of the method and a compromise must be found between method precision and computation time. The study shows the importance of the current carrying path representation in the electrode on the deduced magnetic field. The best compromise consists of using the B and S formulation on the walls and/or edges of the calculation domain to determine the boundary conditions and to solve the vector potential in a 2D system. This approach provides results identical to those obtained using the B and S formulation over the entire domain but with a considerable decrease in calculation time.

  12. Q-switching and efficient harmonic generation from a single-mode LMA photonic bandgap rod fiber laser

    DEFF Research Database (Denmark)

    Laurila, Marko; Saby, Julien; Alkeskjold, Thomas T.

    2011-01-01

    We demonstrate a Single-Mode (SM) Large-Mode-Area (LMA) ytterbium-doped PCF rod fiber laser with stable and close to diffraction limited beam quality with 110W output power. Distributed-Mode-Filtering (DMF) elements integrated in the cladding of the rod fiber provide a robust spatial mode...... with a Mode-Field-Diameter (MFD) of 59 mu m. We further demonstrate high pulse energy Second-Harmonic-Generation (SHG) and Third Harmonic Generation (THG) using a simple Q-switched single-stage rod fiber laser cavity architecture reaching pulse energies up to 1mJ at 515nm and 0.5mJ at 343nm. (C) 2011 Optical...

  13. Quantum discord dynamics of two qubits in single-mode cavities

    International Nuclear Information System (INIS)

    Wang Chen; Chen Qing-Hu

    2013-01-01

    The dynamics of quantum discord for two identical qubits in two independent single-mode cavities and a common single-mode cavity are discussed. For the initial Bell state with correlated spins, while the entanglement sudden death can occur, the quantum discord vanishes only at discrete moments in the independent cavities and never vanishes in the common cavity. Interestingly, quantum discord and entanglement show opposite behavior in the common cavity, unlike in the independent cavities. For the initial Bell state with anti-correlated spins, quantum discord and entanglement behave in the same way for both independent cavities and a common cavity. It is found that the detunings always stabilize the quantum discord. (general)

  14. High Energy, Single-Mode, All-Solid-State and Tunable UV Laser Transmitter

    Science.gov (United States)

    Prasad, Narasimha S.; Singh, Upendra N.; Hovis, FLoyd

    2007-01-01

    A high energy, single mode, all solid-state Nd:YAG laser primarily for pumping an UV converter is developed. Greater than 1 J/pulse at 50 HZ PRF and pulse widths around 22 ns have been demonstrated. Higher energy, greater efficiency may be possible. Refinements are known and practical to implement. Technology Demonstration of a highly efficient, high-pulse-energy, single mode UV wavelength generation using flash lamp pumped laser has been achieved. Greater than 90% pump depletion is observed. 190 mJ extra-cavity SFG; IR to UV efficiency > 21% (> 27% for 1 mJ seed). 160 mJ intra-cavity SFG; IR to UV efficiency up to 24% Fluence laser is being refined to match or exceed the above UV converter results. Currently the Nd:YAG pump laser development is a technology demonstration. System can be engineered for compact packaging.

  15. Thermal neutron standard fields with the KUR heavy water facility

    International Nuclear Information System (INIS)

    Kanda, K.; Kobayashi, K.; Shibata, T.

    1978-01-01

    A heavy water facility attached to the KUR (Kyoto University Reactor, swimming pool type, 5 MW) yields pure thermal neutrons in the Maxwellian distribution. The facility is faced to the core of KUR and it contains about 2 tons of heavy water. The thickness of the layer is about 140 cm. The neutron spectrum was measured with the time of flight technique using a fast chopper. The measured spectrum was in good agreement with the Maxwellian distribution in all energy region for thermal neutrons. The neutron temperature was slightly higher than the heavy water temperature. The contamination of epithermal and fast neutrons caused by photo-neutrons of the γ-n reaction of heavy water was very small. The maximum intensity of thermal neutrons is 3x10 11 n/cm 2 sec. When the bismuth scatterer is attached, the gamma rays contamination is eliminated by the ratio of 0.05 of gamma rays to neutrons in rem. This standard neutron field has been used for such experiments as thermal neutron cross section measurement, detector calibration, activation analysis, biomedical purposes etc. (author)

  16. Combined effect of viscosity and vorticity on single mode Rayleigh-Taylor instability bubble growth

    International Nuclear Information System (INIS)

    Banerjee, Rahul; Mandal, Labakanta; Roy, S.; Khan, M.; Gupta, M. R.

    2011-01-01

    The combined effect of viscosity and vorticity on the growth rate of the bubble associated with single mode Rayleigh-Taylor instability is investigated. It is shown that the effect of viscosity on the motion of the lighter fluid associated with vorticity accumulated inside the bubble due to mass ablation may be such as to reduce the net viscous drag on the bubble exerted by the upper heavier fluid as the former rises through it.

  17. Cavity Formation Modeling of Fiber Fuse in Single-Mode Optical Fibers

    Directory of Open Access Journals (Sweden)

    Yoshito Shuto

    2017-01-01

    Full Text Available The evolution of a fiber-fuse phenomenon in a single-mode optical fiber was studied theoretically. To clarify both the silica-glass densification and cavity formation, which have been observed in fiber fuse propagation, we investigated a nonlinear oscillation model using the Van Der Pol equation. This model was able to phenomenologically explain both the densification of the core material and the formation of periodic cavities in the core layer as a result of a relaxation oscillation.

  18. Single Mode Optical Fiber based Refractive Index Sensor using Etched Cladding

    OpenAIRE

    Kumar, Ajay; Gupta, Geeta; Mallik, Arun; Bhatnagar, Anuj

    2011-01-01

    The use of optical fiber for sensor applications is a topic of current interest. We report the fabrication of etched single mode optical fiber based refractive index sensor. Experiments are performed to determine the etch rate of fiber in buffered hydrofluoric acid, which can be high or low depending upon the temperature at which etching is carried out. Controlled wet etching of fiber cladding is performed using these measurements and etched fiber region is tested for refractive index sensing...

  19. Single-mode waveguides with SU-8 polymer core and cladding for MOEMS applications

    OpenAIRE

    Nordström, Maria; Zauner, Dan; Boisen, Anja; Hübner, Jörg

    2007-01-01

    Fabrication and optical characterization of singlemode polymeric embedded waveguides are performed. A specific material combination (SU-8 2005 as core and the modified SU-8 mr-L 6050XP as cladding) is chosen in order to obtain a small refractive index difference for single-mode propagation combined with the conventional fabrication method UV lithography to facilitate the integration of different types of optical detection methods on lab-on-a-chip systems. We analyze the behavior of the refrac...

  20. Electrically-pumped, broad-area, single-mode photonic crystal lasers.

    Science.gov (United States)

    Zhu, Lin; Chak, Philip; Poon, Joyce K S; DeRose, Guy A; Yariv, Amnon; Scherer, Axel

    2007-05-14

    Planar broad-area single-mode lasers, with modal widths of the order of tens of microns, are technologically important for high-power applications and improved coupling efficiency into optical fibers. They may also find new areas of applications in on-chip integration with devices that are of similar size scales, such as for spectroscopy in microfluidic chambers or optical signal processing with micro-electromechanical systems. An outstanding challenge is that broad-area lasers often require external means of control, such as injection-locking or a frequency/spatial filter to obtain single-mode operation. In this paper, we propose and demonstrate effective index-guided, large-area, edge-emitting photonic crystal lasers driven by pulsed electrical current injection at the optical telecommunication wavelength of 1550 nm. By suitable design of the photonic crystal lattice, our lasers operate in a single mode with a 1/e(2) modal width of 25 microm and a length of 600 microm.

  1. From free fields to AdS space: Thermal case

    International Nuclear Information System (INIS)

    Furuuchi, Kazuyuki

    2005-01-01

    We analyze the reorganization of free field theory correlators to closed string amplitudes investigated in previous papers in the case of Euclidean thermal field theory and study how the dual bulk geometry is encoded on them. The expectation value of Polyakov loop, which is an order parameter for confinement-deconfinement transition, is directly reflected on the dual bulk geometry. The dual geometry of the confined phase is found to be AdS space periodically identified in Euclidean time direction. The gluing of Schwinger parameters, which is a key step for the reorganization of field theory correlators, works in the same way as in the nonthermal case. In the deconfined phase the gluing is made possible only by taking the dual geometry correctly. The dual geometry for the deconfined phase does not have a noncontractable circle in the Euclidean time direction

  2. Basics of thermal field theory a tutorial on perturbative computations

    CERN Document Server

    Laine, Mikko

    2016-01-01

    This book presents thermal field theory techniques, which can be applied in both cosmology and the theoretical description of the QCD plasma generated in heavy-ion collision experiments. It focuses on gauge interactions (whether weak or strong), which are essential in both contexts. As well as the many differences in the physics questions posed and in the microscopic forces playing a central role, the authors also explain the similarities and the techniques, such as the resummations, that are needed for developing a formally consistent perturbative expansion. The formalism is developed step by step, starting from quantum mechanics; introducing scalar, fermionic and gauge fields; describing the issues of infrared divergences; resummations and effective field theories; and incorporating systems with finite chemical potentials. With this machinery in place, the important class of real-time (dynamic) observables is treated in some detail. This is followed by an overview of a number of applications, ranging from t...

  3. Nonequlibrium dynamics of scalar fields in a thermal bath

    International Nuclear Information System (INIS)

    Anisimov, A.; Buchmueller, W.; Drewes, M.; Mendizabal, S.

    2008-12-01

    We study the approach to equilibrium for a scalar field which is coupled to a large thermal bath. Our analysis of the initial value problem is based on Kadanoff-Baym equations which are shown to be equivalent to a stochastic Langevin equation. The interaction with the thermal bath generates a temperature-dependent spectral density, either through decay and inverse decay processes or via Landau damping. In equilibrium, energy density and pressure are determined by the Bose-Einstein distribution function evaluated at a complex quasi-particle pole. The time evolution of the statistical propagator is compared with solutions of the Boltzmann equations for particles as well as quasi-particles. The dependence on initial conditions and the range of validity of the Boltzmann approximation are determined. (orig.)

  4. Control of thermal therapies with moving power deposition field

    International Nuclear Information System (INIS)

    Arora, Dhiraj; Minor, Mark A; Skliar, Mikhail; Roemer, Robert B

    2006-01-01

    A thermal therapy feedback control approach to control thermal dose using a moving power deposition field is developed and evaluated using simulations. A normal tissue safety objective is incorporated in the controller design by imposing constraints on temperature elevations at selected normal tissue locations. The proposed control technique consists of two stages. The first stage uses a model-based sliding mode controller that dynamically generates an 'ideal' power deposition profile which is generally unrealizable with available heating modalities. Subsequently, in order to approximately realize this spatially distributed idealized power deposition, a constrained quadratic optimizer is implemented to compute intensities and dwell times for a set of pre-selected power deposition fields created by a scanned focused transducer. The dwell times for various power deposition profiles are dynamically generated online as opposed to the commonly employed a priori-decided heating strategies. Dynamic intensity and trajectory generation safeguards the treatment outcome against modelling uncertainties and unknown disturbances. The controller is designed to enforce simultaneous activation of multiple normal tissue temperature constraints by rapidly switching between various power deposition profiles. The hypothesis behind the controller design is that the simultaneous activation of multiple constraints substantially reduces treatment time without compromising normal tissue safety. The controller performance and robustness with respect to parameter uncertainties is evaluated using simulations. The results demonstrate that the proposed controller can successfully deliver the desired thermal dose to the target while maintaining the temperatures at the user-specified normal tissue locations at or below the maximum allowable values. Although demonstrated for the case of a scanned focused ultrasound transducer, the developed approach can be extended to other heating modalities with

  5. Provisional maps of thermal areas in Yellowstone National Park, based on satellite thermal infrared imaging and field observations

    Science.gov (United States)

    Vaughan, R. Greg; Heasler, Henry; Jaworowski, Cheryl; Lowenstern, Jacob B.; Keszthelyi, Laszlo P.

    2014-01-01

    Maps that define the current distribution of geothermally heated ground are useful toward setting a baseline for thermal activity to better detect and understand future anomalous hydrothermal and (or) volcanic activity. Monitoring changes in the dynamic thermal areas also supports decisions regarding the development of Yellowstone National Park infrastructure, preservation and protection of park resources, and ensuring visitor safety. Because of the challenges associated with field-based monitoring of a large, complex geothermal system that is spread out over a large and remote area, satellite-based thermal infrared images from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) were used to map the location and spatial extent of active thermal areas, to generate thermal anomaly maps, and to quantify the radiative component of the total geothermal heat flux. ASTER thermal infrared data acquired during winter nights were used to minimize the contribution of solar heating of the surface. The ASTER thermal infrared mapping results were compared to maps of thermal areas based on field investigations and high-resolution aerial photos. Field validation of the ASTER thermal mapping is an ongoing task. The purpose of this report is to make available ASTER-based maps of Yellowstone’s thermal areas. We include an appendix containing the names and characteristics of Yellowstone’s thermal areas, georeferenced TIFF files containing ASTER thermal imagery, and several spatial data sets in Esri shapefile format.

  6. Thermal and Field Enhanced Photoemission Comparison of Theory to Experiment

    CERN Document Server

    Lynn-Jensen, Kevin

    2004-01-01

    Photocathodes are a critical component of high-gain FEL’s and the analysis of their emission is complex. Relating their performance under laboratory conditions to conditions of an rf photoinjector is difficult. Useful models must account for cathode surface conditions and material properties, as well as drive laser parameters. We have developed a time-dependent model accounting for the effects of laser heating and thermal propagation on photoemission. It accounts for surface conditions (coating, field enhancement, reflectivity), laser parameters (duration, intensity, wavelength), and material characteristics (reflectivity, laser penetration depth, scattering rates) to predict current distribution and quantum efficiency. The applicatIon will focus on photoemission from metals and, in particular, dispenser photocathodes: the later introduces complications such as coverage non-uniformity and field enhancement. The performance of experimentally characterized photocathodes will be extrapolated to 0.1 - 1 nC bunch...

  7. The PTB thermal neutron reference field at GeNF

    International Nuclear Information System (INIS)

    Boettger, R.; Friedrich, H.; Janssen, H.

    2004-01-01

    The experimental setup and procedure for the characterization of the thermal neutron reference field established at the Geesthacht neutron facility (GeNF) of the GKSS is described. The neutron beam, free in air, with a maximum flux of 10 6 s -1 , can easily be reduced to less than 10 4 s -1 by using a diaphragm variable in size and without changing the beam divergence. Also, the spectral distribution with a mean energy of 45 meV, measured by time-of-flight over a 6.6 m long flight path, is independent of the beam current chosen. In the 2002/2003 experiments reported here, a 6 Li glass detector was employed to determine the absolute beam current and to calibrate the 3 He transmission beam monitor. In addition, activation measurements of gold foils were carried out at a reduced beam divergence. The results agree within ±2%. Furthermore, the beam is characterized by a low gamma background intensity and a negligible fraction of epithermal neutrons. Irradiations in combination with a scanner device to achieve a homogeneously illuminated scan field have shown that the thermal beam is well suited for dosemeter development and for the calibration of radiation protection instruments. (orig.)

  8. The PTB thermal neutron reference field at GeNF

    Energy Technology Data Exchange (ETDEWEB)

    Boettger, R.; Friedrich, H.; Janssen, H.

    2004-07-01

    The experimental setup and procedure for the characterization of the thermal neutron reference field established at the Geesthacht neutron facility (GeNF) of the GKSS is described. The neutron beam, free in air, with a maximum flux of 10{sup 6} s{sup -1}, can easily be reduced to less than 10{sup 4} s{sup -1} by using a diaphragm variable in size and without changing the beam divergence. Also, the spectral distribution with a mean energy of 45 meV, measured by time-of-flight over a 6.6 m long flight path, is independent of the beam current chosen. In the 2002/2003 experiments reported here, a {sup 6}Li glass detector was employed to determine the absolute beam current and to calibrate the {sup 3}He transmission beam monitor. In addition, activation measurements of gold foils were carried out at a reduced beam divergence. The results agree within {+-}2%. Furthermore, the beam is characterized by a low gamma background intensity and a negligible fraction of epithermal neutrons. Irradiations in combination with a scanner device to achieve a homogeneously illuminated scan field have shown that the thermal beam is well suited for dosemeter development and for the calibration of radiation protection instruments. (orig.)

  9. Optical measuring system with an interrogator and a polymer-based single-mode fibre optic sensor system

    DEFF Research Database (Denmark)

    2017-01-01

    The present invention relates to an optical measuring system comprising a polymer-based single-mode fibre-optic sensor system (102), an optical interrogator (101), and an optical arrangement (103) interconnecting the optical interrogator (101) and the polymer-based single-mode fibre-optic sensor...... system (102). The invention further relates to an optical interrogator adapted to be connected to a polymer-based single-mode fibre-optic sensor system via an optical arrangement. The interrogator comprises a broadband light source arrangement (104) and a spectrum analysing arrangement which receives...

  10. GaSb-based single-mode distributed feedback lasers for sensing (Conference Presentation)

    Science.gov (United States)

    Gupta, James A.; Bezinger, Andrew; Lapointe, Jean; Poitras, Daniel; Aers, Geof C.

    2017-02-01

    GaSb-based tunable single-mode diode lasers can enable rapid, highly-selective and highly-sensitive absorption spectroscopy systems for gas sensing. In this work, single-mode distributed feedback (DFB) laser diodes were developed for the detection of various trace gases in the 2-3.3um range, including CO2, CO, HF, H2S, H2O and CH4. The lasers were fabricated using an index-coupled grating process without epitaxial regrowth, making the process significantly less expensive than conventional DFB fabrication. The devices are based on InGaAsSb/AlGaAsSb separate confinement heterostructures grown on GaSb by molecular beam epitaxy. DFB lasers were produced using a two step etch process. Narrow ridge waveguides were first defined by optical lithography and etched into the semiconductor. Lateral gratings were then defined on both sides of the ridge using electron-beam lithography and etched to produce the index-grating. Effective index modeling was used to optimize the ridge width, etch depths and the grating pitch to ensure single-lateral-mode operation and adequate coupling strength. The effective index method was further used to simulate the DFB laser emission spectrum, based on a transfer matrix model for light transmission through the periodic structure. The fabricated lasers exhibit single-mode operation which is tunable through the absorption features of the various target gases by adjustment of the drive current. In addition to the established open-path sensing applications, these devices have great potential for optoelectronic integrated gas sensors, making use of integrated photodetectors and possibly on-chip Si photonics waveguide structures.

  11. A novel high-efficiency single-mode quantum dot single photon source

    DEFF Research Database (Denmark)

    Gerard, J.M.; Gregersen, Niels; Nielsen, Torben Roland

    2008-01-01

    We present a novel single-mode single photon source exploiting the emission of a semiconductor quantum dot (QD) located inside a photonic wire. Besides an excellent coupling (>95%) of QD spontaneous emission to the fundamental guided mode [1], we show that a single photon collection efficiency...... above 80% within a 0.5 numerical aperture can be achieved using a bottom Bragg mirror and a tapering of the nanowire tip. Because this photon collection strategy does not exploit the Purcell effect, it could also be efficiently applied to broadband single photon emitters such as F-centers in diamond....

  12. Stochastic resonance in a single-mode laser driven by frequency modulated signal and coloured noises

    Institute of Scientific and Technical Information of China (English)

    Jin Guo-Xiang; Zhang Liang-Ying; Cao Li

    2009-01-01

    By adding frequency modulated signals to the intensity equation of gain-noise model of the single-mode laser driven by two coloured noises which are correlated, this paper uses the linear approximation method to calculate the power spectrum and signal-to-noise ratio (SNR) of the laser intensity. The results show that the SNR appears typical stochastic resonance with the variation of intensity of the pump noise and quantum noise. As the amplitude of a modulated signal has effects on the SNR, it shows suppression, monotone increasing, stochastic resonance, and multiple stochastic resonance with the variation of the frequency of a carrier signal and modulated signal.

  13. Cantilever-based sensor with integrated optical read-out using single mode waveguides

    DEFF Research Database (Denmark)

    Nordström, Maria; Zauner, Dan; Calleja, Montserrat

    2007-01-01

    This work presents the design, fabrication and mechanical characterisation of an integrated optical read-out scheme for cantilever-based biosensors. A cantilever can be used as a biosensor by monitoring its bending caused by the surface stress generated due to chemical reactions occurring on its...... surface. Here, we present a novel integrated optical read-out scheme based on single-mode waveguides that enables the fabrication of a compact system. The complete system is fabricated in the polymer SU-8. This manuscript shows the principle of operation and the design well as the fabrication...

  14. Single-mode waveguides with SU-8 polymer core and cladding for MOEMS applications

    DEFF Research Database (Denmark)

    Nordström, Maria; Zauner, Dan; Boisen, Anja

    2007-01-01

    Fabrication and optical characterization of singlemode polymeric embedded waveguides are performed. A specific material combination (SU-8 2005 as core and the modified SU-8 mr-L 6050XP as cladding) is chosen in order to obtain a small refractive index difference for single-mode propagation combined...... can fabricate waveguides with an index difference in the order of 10−3, where both the core material and the cladding material are based on SU-8. The refractive index measurements are performed on thin polymeric films, while further optical characterizations are performed on waveguides with a height...

  15. Self-pulsing and chaos in inhomogeneously broadened single mode lasers

    Energy Technology Data Exchange (ETDEWEB)

    Graham, R; Cho, Y

    1983-08-01

    A four-dimensional model and a six-dimensional model describing the self-pulsing instabilities and chaotic dynamics of inhomogeneously broadened single-mode lasers are derived as the first two steps of an infinite hierarchy of approximations increasing in accuracy and complexity. The results of a linear stability analysis of the time-independent states and some numerical solutions are given to show the various types of dynamic behavior which can occur in these models. The dynamic behavior is found to be much more complex than in the homogeneously broadened case and is obtained under physically more realistic conditions. 10 references.

  16. Effects of underwater turbulence on laser beam propagation and coupling into single-mode optical fiber.

    Science.gov (United States)

    Hanson, Frank; Lasher, Mark

    2010-06-01

    We characterize and compare the effects of turbulence on underwater laser propagation with theory. Measurements of the coupling efficiency of the focused beam into a single-mode fiber are reported. A simple tip-tilt control system, based on the position of the image centroid in the focal plane, was shown to maintain good coupling efficiency for a beam radius equal to the transverse coherence length, r(0). These results are relevant to high bandwidth communication technology that requires good spatial mode quality.

  17. Writing single-mode waveguides in lithium niobate by ultra-low intensity solitons

    International Nuclear Information System (INIS)

    Fazio, E.; Ramadan, W.; Petris, A.; Chauvet, M.; Bosco, A.; Vlad, V.I.; Bertolotti, M.

    2005-01-01

    Optical waveguides can be conveniently written in photorefractive materials by using spatial solitons. We have generated bright spatial solitons inside lithium niobate which allow single-mode light propagation. Efficient waveguides have been generated with CW light powers as high as few microwatts. According to the soliton formation, waveguides can be formed with different shapes. Due to the slow response time of the lithium niobate, both for soliton formation and relaxation, the soliton waveguide remains memorised for a long time, of the order of months

  18. Creation of Magnetic Fields by Electrostatic and Thermal Fluctuations

    International Nuclear Information System (INIS)

    Saleem, Hamid

    2009-01-01

    It is pointed out that the electrostatic and thermal fluctuations are the main source of magnetic fields in unmagnetized inhomogeneous plasmas. The unmagnetized inhomogeneous plasmas can support a low frequency electromagnetic ion wave as a normal mode like Alfven wave of magnetized plasmas. But this is a coupled mode produced by the mixing of longitudinal and transverse components of perturbed electric field due to density inhomogeneity. The ion acoustic wave does not remain electrostatic in non-uniform plasmas. On the other hand, a low frequency electrostatic wave can also exist in the pure electron plasmas and it couples with ion acoustic wave when ions are dynamic. These waves can become unstable when density and temperature gradients are parallel to each other as can be the case of laser plasmas and is the common situation in stellar cores. The main instability condition for the electrostatic and electromagnetic modes is the same (2/3)κ n T (where κ n and κ T are inverse of the scale lengths of gradients of density and electron temperature, respectively). This indicates that the electrostatic and magnetic field fluctuations are strongly coupled in unmagnetized nonuniform plasmas.

  19. Investigations in thermal fields and stress fields induced by electron beam welding

    International Nuclear Information System (INIS)

    Basile, G.

    1979-12-01

    This document presents the thermal study of electron beam welding and identifies stresses and strains from welding: description of the operating principles of the electron gun and characterization of various welding parameters, examination of the temperature fields during electron beam welding development of various mathematic models and comparison with experimental results, measurement and calculation of stresses and strains in the medium plane of the welding assembly, residual stresses analysis [fr

  20. Bend-insensitive single-mode photonic crystal fiber with ultralarge effective area for dual applications

    Science.gov (United States)

    Islam, Md. Asiful; Alam, M. Shah

    2013-05-01

    A novel photonic crystal fiber (PCF) having circular arrangement of cladding air holes has been designed and numerically optimized to obtain a bend insensitive single mode fiber with large mode area for both wavelength division multiplexing (WDM) communication and fiber-to-the-home (FTTH) application. The bending loss of the proposed bent PCF lies in the range of 10-3 to 10-4 dB/turn or lower over 1300 to 1700 nm, and 2 × 10-4 dB/turn at the wavelength of 1550 nm for a 30-mm bend radius with a higher order mode (HOM) cut-off frequency below 1200 nm for WDM application. When the whole structure of the PCF is scaled down, a bending loss of 6.78×10-4 dB/turn at 1550 nm for a 4-mm bend radius is obtained, and the loss remains in the order of 10-4 dB/turn over the same range of wavelength with an HOM cut-off frequency below 700 nm, and makes the fiber useful for FTTH applications. Furthermore, this structure is also optimized to show a splice loss near zero for fusion-splicing to a conventional single-mode fiber (SMF).

  1. Simple immunoglobulin G sensor based on thin core single-mode fiber

    Science.gov (United States)

    Zheng, Yingfang; Lang, Tingting; Shen, Tingting; Shen, Changyu

    2018-03-01

    In this paper, a simple fiber biosensor (FOB) for immunoglobulin G (IgG) detection is designed and experimentally verified. The FOB is constructed by a 20 mm long thin core single-mode fiber (TCSMF) sandwiched between two single-mode optical fibers (SMFs). First, the refractive index (RI) sensitivity of the fiber structures is calculated by the beam propagation method. The refractive index sensing experiment is performed using different concentrations of glycerol solutions, and the experimental results are mostly consistent with the simulation predictions. The experimental RI sensitivity increases with the surrounding RI and reaches 82.7 nm/RIU. Then the surface of the FOB is functionalized by APTES for covalent bonding. The human IgG and goat anti-human IgG are chosen as a bioconjugated pair to examine the bio-sensing effectiveness of this FOB. The sensitivity of IgG detection is determined to be 10.4 nm/(mg/ml). And the serum IgG concentration in normal adults lies within the range of 6-16 mg/ml (Worsfold et al., 1985), so the sensor is applicable to human IgG monitoring. The specificity of the FOB is also verified by a contrast experiment conducted using rabbit immunoglobulin G. The proposed FOB is simple, low loss, cost-effective, and can be used for various biological and chemical applications.

  2. Effective field theory of thermal Casimir interactions between anisotropic particles.

    Science.gov (United States)

    Haussman, Robert C; Deserno, Markus

    2014-06-01

    We employ an effective field theory (EFT) approach to study thermal Casimir interactions between objects bound to a fluctuating fluid surface or interface dominated by surface tension, with a focus on the effects of particle anisotropy. The EFT prescription disentangles the constraints imposed by the particles' boundaries from the calculation of the interaction free energy by constructing an equivalent point particle description. The finite-size information is captured in a derivative expansion that encodes the particles' response to external fields. The coefficients of the expansion terms correspond to generalized tensorial polarizabilities and are found by matching the results of a linear response boundary value problem computed in both the full and effective theories. We demonstrate the versatility of the EFT approach by constructing the general effective Hamiltonian for a collection of particles of arbitrary shapes. Taking advantage of the conformal symmetry of the Hamiltonian, we discuss a straightforward conformal mapping procedure to systematically determine the polarizabilities and derive a complete description for elliptical particles. We compute the pairwise interaction energies to several orders for nonidentical ellipses as well as their leading-order triplet interactions and discuss the resulting preferred pair and multibody configurations. Furthermore, we elaborate on the complications that arise with pinned particle boundary conditions and show that the powerlike corrections expected from dimensional analysis are exponentially suppressed by the leading-order interaction energies.

  3. Fourier-transform ghost imaging with pure far-field correlated thermal light

    International Nuclear Information System (INIS)

    Liu Honglin; Shen Xia; Han Shensheng; Zhu Daming

    2007-01-01

    Pure far-field correlated thermal light beams are created with phase grating, and Fourier-transform ghost imaging depending only on the far-field correlation is demonstrated experimentally. Theoretical analysis and the results of experimental investigation of this pure far-field correlated thermal light are presented. Applications which may be exploited with this imaging scheme are discussed

  4. Modeling satellite-Earth quantum channel downlinks with adaptive-optics coupling to single-mode fibers

    Science.gov (United States)

    Gruneisen, Mark T.; Flanagan, Michael B.; Sickmiller, Brett A.

    2017-12-01

    The efficient coupling of photons from a free-space quantum channel into a single-mode optical fiber (SMF) has important implications for quantum network concepts involving SMF interfaces to quantum detectors, atomic systems, integrated photonics, and direct coupling to a fiber network. Propagation through atmospheric turbulence, however, leads to wavefront errors that degrade mode matching with SMFs. In a free-space quantum channel, this leads to photon losses in proportion to the severity of the aberration. This is particularly problematic for satellite-Earth quantum channels, where atmospheric turbulence can lead to significant wavefront errors. This report considers propagation from low-Earth orbit to a terrestrial ground station and evaluates the efficiency with which photons couple either through a circular field stop or into an SMF situated in the focal plane of the optical receiver. The effects of atmospheric turbulence on the quantum channel are calculated numerically and quantified through the quantum bit error rate and secure key generation rates in a decoy-state BB84 protocol. Numerical simulations include the statistical nature of Kolmogorov turbulence, sky radiance, and an adaptive-optics system under closed-loop control.

  5. Microwave-assisted combustion synthesis of NiAl intermetallics in a single mode applicator: Modeling and optimisation

    International Nuclear Information System (INIS)

    Poli, G.; Sola, R.; Veronesi, P.

    2006-01-01

    The microwave-assisted combustion synthesis of NiAl intermetallics in a single mode applicator has been simulated numerically and performed with the aim of achieving the highest yields, energy efficiency and process reproducibility. The electromagnetic field modeling of the microwave system allowed to chose the proper experimental set-up and the materials more suitable for the application, minimising the reflected power and the risks of arcing. In all the experimental conditions tested, conversions of 3-5 g 1:1 atomic ratio Ni and Al powder compacts into NiAl ranged from 98.7% to 100%, requiring from 30 to 180 s with power from 500 to 1500 W. The optimisation procedure allowed to determine and quantify the effects of the main process variables on the ignition time, the NiAl yields and the specific energy consumption, leading to a fast, reproducible and cost-effective process of microwave-assisted combustion synthesis of NiAl intermetallics

  6. “MODAL NOISE” IN SINGLE-MODE FIBERS: A CAUTIONARY NOTE FOR HIGH PRECISION RADIAL VELOCITY INSTRUMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Halverson, Samuel; Roy, Arpita; Mahadevan, Suvrath [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Schwab, Christian, E-mail: shalverson@psu.edu [Macquarie University, Sydney, NSW 2109 (Australia)

    2015-12-01

    Exploring the use of single-mode fibers (SMFs) in high precision Doppler spectrometers has become increasingly attractive since the advent of diffraction-limited adaptive optics systems on large-aperture telescopes. Spectrometers fed with these fibers can be made significantly smaller than typical “seeing-limited” instruments, greatly reducing cost and overall complexity. Importantly, classical mode interference and speckle issues associated with multi-mode fibers, also known as “modal noise,” are mitigated when using SMFs, which also provide perfect radial and azimuthal image scrambling. However, SMFs do support multiple polarization modes, an issue that is generally ignored for larger-core fibers given the large number of propagation modes. Since diffraction gratings used in most high resolution astronomical instruments have dispersive properties that are sensitive to incident polarization changes, any birefringence variations in the fiber can cause variations in the efficiency profile, degrading illumination stability. Here we present a cautionary note outlining how the polarization properties of SMFs can affect the radial velocity (RV) measurement precision of high resolution spectrographs. This work is immediately relevant to the rapidly expanding field of diffraction-limited, extreme precision RV spectrographs that are currently being designed and built by a number of groups.

  7. Report on first masing and single mode locking in a prebunched beam FEM oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, M.; Eichenbaum, A.; Kleinman, H. [Tel-Aviv Univ., Ramat-Aviv (Israel)] [and others

    1995-12-31

    Radiation characteristics of a table-top free electron maser (FEM) are described in this paper. The FEM employs a prebunched electron beam and is operated as an oscillator in the low-gain collective (Raman) regime. Using electron beam prebunching single mode locking at any one of the possible oscillation modes was obtained. The electron beam is prebunched by a microwave tube section before it is injected into the wiggler. By tuning the electron beam bunching frequency, the FEM oscillation frequency can be locked to any eigen frequency of the resonant waveguide cavity which is within the frequency band of net gain of the FEM. The oscillation build up process is sped up, when the FEM operates with a prebunched electron beam, and the build-up time of radiation is shortened significantly. First measurements of masing with and without prebunching and characterization of the emitted radiation are reported.

  8. Diffusion-cooled high-power single-mode waveguide CO2 laser for transmyocardial revascularization

    Science.gov (United States)

    Berishvili, I. I.; Bockeria, L. A.; Egorov, E. N.; Golubev, Vladimir S.; Galushkin, Michail G.; Kheliminsky, A. A.; Panchenko, Vladislav Y.; Roshin, A. P.; Sigaev, I. Y.; Vachromeeva, M. N.; Vasiltsov, Victor V.; Yoshina, V. I.; Zabelin, Alexandre M.; Zelenov, Evgenii V.

    1999-01-01

    The paper presents the results on investigations and development of multichannel waveguide CO2 laser with diffusion cooling of active medium excited by discharge of audio-frequency alternating current. The description of high-power single-mode CO2 laser with average beam power up to 1 kW is presented. The result of measurement of the laser basic parameters are offered, as well as the outcomes of performances of the laser head with long active zone, operating in waveguide mode. As an example of application of these laser, various capabilities a description of the developed medical system 'Genom' used in the transmyocardial laser revascularization (TMLR) procedure and clinical results of the possibilities of the TMLR in the surgical treatment are presented.

  9. Development of a 10-decade single-mode reactor flux monitoring system

    International Nuclear Information System (INIS)

    Valentine, K.H.; Shepard, R.L.; Falter, K.G.; Reese, W.B.

    1988-01-01

    Conventional wide-range neutron channels employ three optional modes to monitor the required flux range from source levels to full power (typically 10 or more decades). Difficult calibrations are necessary to provide a continuous output signal when such a system switches from counting mode in the source range to mean-square voltage mode in the midrange to dc current mode in the power range. In an ORNL proof-of-principle test, a method of extended range counting was implemented with a fission counter and conventional wide-band pulse processing electronics to provide a single-mode, monotonically increasing signal that spanned /approximately 10/ decades of neutron flux. Ongoing work includes design, fabrication, and testing of a comlpete neutron flux monitoring system suitable for advanced liquid metal reactor designs. 6 refs., 4 figs

  10. Stochastic resonance for signal-modulated pump noise in a single-mode laser

    Institute of Scientific and Technical Information of China (English)

    Liangying Zhang; Li Cao; Fahui Zhu

    2006-01-01

    By adopting the gain-noise model of the single-mode laser in which with bias and periodical signals serve as inputs, combining with the effect of coloured pump noise, we use the linear approximation method to calculate the power spectrum and signal-to-noise ratio (SNR) of the laser intensity under the condition of pump noise and quantum noise cross-related in the form of δ function. It is found that with the change of pump noise correlation time, both SNR and the output power will occur stochastic resonance (SR). If the bias signal α is very small, changing the intensities of pump noise and quantum noise respectively does not lead to the appearance of SR in the SNR; while α increases to a certain number, SR appears.

  11. Pulse Propagation in Presence of Polarization Mode Dispersion and Chromatic Dispersion in Single Mode Fibers

    Directory of Open Access Journals (Sweden)

    Hassan Abid Yasser

    2013-01-01

    Full Text Available The presence of (first and second orders polarization mode dispersion (PMD, chromatic dispersion, and initial chirp makes effects on the propagated pulses in single mode fiber. Nowadays, there is not an accurate mathematical formula that describes the pulse shape in the presence of these effects. In this work, a theoretical study is introduced to derive a generalized formula. This formula is exactly approached to mathematical relations used in their special cases. The presence of second-order PMD (SOPMD will not affect the orthogonality property between the principal states of polarization. The simulation results explain that the interaction of the SOPMD components with the conventional effects (chromatic dispersion and chirp will cause a broadening/narrowing and shape distortion. This changes depend on the specified values of SOPMD components as well as the present conventional parameters.

  12. Three-dimensional single-mode nonlinear ablative Rayleigh-Taylor instability

    International Nuclear Information System (INIS)

    Yan, R.; Aluie, H.; Betti, R.; Sanz, J.; Liu, B.; Frank, A.

    2016-01-01

    The nonlinear evolution of the single-mode ablative Rayleigh-Taylor instability is studied in three dimensions. As the mode wavelength approaches the cutoff of the linear spectrum (short-wavelength modes), it is found that the three-dimensional (3D) terminal bubble velocity greatly exceeds both the two-dimensional (2D) value and the classical 3D bubble velocity. Unlike in 2D, the 3D short-wavelength bubble velocity does not saturate. The growing 3D bubble acceleration is driven by the unbounded accumulation of vorticity inside the bubble. The vorticity is transferred by mass ablation from the Rayleigh-Taylor spikes to the ablated plasma filling the bubble volume

  13. PREPARATION OF THE SINGLE MODE PLANAR OPTICAL SPLITTER MODULES AND THEIR CHARACTERIZATIONS

    Directory of Open Access Journals (Sweden)

    Vu Doan Mien

    2017-11-01

    Full Text Available Optical splitter modules have been prepared based on 1x8 single mode silica planar waveguide optical splitter chips with 250 µm spacing and v-groove fiber arrays for applications in fiber optic communications. We report the technology of precise optical coupling and packaging of the splitter modules and the measurements of the insertion loss (< 11 dB,  uniformity (< 0.80 dB and polarization dependence loss (PLD < 0.10 dB as well as the lateral profile and the image of the input and output lights for the wavelengths of 1310 nm and 1550 nm. The main characteristics of the prepared splitter modules are about the same for the commercial available products. The prepared modules have been tested for operation in the conditions of wide temperature range (5–80°C and humidity range (50–98% and no changes in the main characteristics were observed.

  14. Stable Single-Mode Operation of Distributed Feedback Quantum Cascade Laser by Optimized Reflectivity Facet Coatings

    Science.gov (United States)

    Wang, Dong-Bo; Zhang, Jin-Chuan; Cheng, Feng-Min; Zhao, Yue; Zhuo, Ning; Zhai, Shen-Qiang; Wang, Li-Jun; Liu, Jun-Qi; Liu, Shu-Man; Liu, Feng-Qi; Wang, Zhan-Guo

    2018-02-01

    In this work, quantum cascade lasers (QCLs) based on strain compensation combined with two-phonon resonance design are presented. Distributed feedback (DFB) laser emitting at 4.76 μm was fabricated through a standard buried first-order grating and buried heterostructure (BH) processing. Stable single-mode emission is achieved under all injection currents and temperature conditions without any mode hop by the optimized antireflection (AR) coating on the front facet. The AR coating consists of a double layer dielectric of Al2O3 and Ge. For a 2-mm laser cavity, the maximum output power of the AR-coated DFB-QCL was more than 170 mW at 20 °C with a high wall-plug efficiency (WPE) of 4.7% in a continuous-wave (CW) mode.

  15. A long-baseline interferometer employing single-mode fiber optics

    Science.gov (United States)

    Shaklan, Stuart

    The idea of the Fiber-Linked Optical Array Telescope proposed by Connes (1987) is to mount several small optical telescopes around the perimeter of a radio dish or other large steerable structure, couple the light into single-mode (SM) fibers, and use the fibers to coherently combine the beams at the output. This paper examines the important properties of SM fibers and then discusses the whole system in general terms, starting with the telescopes and following the light through to the detectors, along with the results of laboratory experiments evaluating the performance of SM fibers. The imaging capabilities of the array were simulated, and it was found that, using 10 telescopes on a 440-m dish, the array obtains images with resolution of the order of 2 milliarc seconds in the visible range.

  16. 3-4.5 μm continuously tunable single mode VECSEL

    Science.gov (United States)

    Fill, M.; Felder, F.; Rahim, M.; Khiar, A.; Zogg, H.

    2012-11-01

    We present continuously tunable Vertical External Cavity Surface Emitting Lasers (VECSEL) in the mid-infrared. The structure based on IV-VI semiconductors is epitaxially grown on a Si-substrates. The VECSEL emit one single mode, which is mode hop-free tunable over 50-100 nm around the center wavelength. In this work, two different devices are presented, emitting at 3.4 μm and 3.9 μm, respectively. The lasers operate near room temperature with thermoelectric stabilization. They are optically pumped, yielding an output power >10 mWp. The axial symmetric emission beam has a half divergence angle of <3.3∘.

  17. Single-mode electrically pumped GaSb-based VCSELs emitting continuous-wave at 2.4 and 2.6 μm

    International Nuclear Information System (INIS)

    Bachmann, Alexander; Arafin, Shamsul; Kashani-Shirazi, Kaveh

    2009-01-01

    Vertical-cavity surface-emitting lasers (VCSELs) are perfect light sources for spectroscopic applications, where properties such as continuous-wave (cw) operation, single-mode emission, high lifetime and often low power consumption are crucial. For applications such as tunable diode laser absorption spectroscopy (TDLAS), there is a growing interest in laser devices emitting in the near- to mid-infrared wavelength range, where many environmentally and technologically important gases show strong absorption lines. The (AlGaIn)(AsSb) material system based on GaSb is the material of choice for covering the 2.0-3.3 μm range. In this paper, we report on electrically pumped single-mode VCSELs with emission wavelengths of 2.4 and 2.6 μm, operating cw at room temperature and beyond. By (electro-) thermal tuning, the emission wavelength can be tuned mode-hop free over a range of several nanometers. In addition, low threshold currents of several milliamperes promise mobile application. In the devices, a structured buried tunnel junction with subsequent overgrowth has been used in order to achieve efficient current confinement, reduced optical losses and increased electrical conductivity. Furthermore, strong optical confinement is introduced in the lasers due to laterally differing cavity lengths.

  18. Interferometric measurement of refractive index modification in a single mode microfiber

    Science.gov (United States)

    Ahmed, Farid; Ahsani, Vahid; Jun, Martin B. G.

    2017-02-01

    Efficient and cost effective measurement of the refractive index profile in an optical fiber is a significant technical job to design and manufacture in-fiber photonic devices and communication systems. For instance, to design fiber gratings, it is required to estimate the refractive index modulation to be inscribed by the fabrication apparatus such as ultraviolet or infrared lasers. Mach-Zehnder interferometer (MZI) based quantification of refractive index change written in single mode microfiber by femtosecond laser radiation is presented in this study. The MZI is constructed by splicing a microfiber (core diameter: 3.75 μm, cladding diameter: 40 μm) between standard single mode fibers. To measure the RI inscribed by infrared femtosecond laser, 200 μm length of the core within the MZI was scanned with laser radiation. As the higher index was written within 200 μm length of the core, the transmission spectrum of the interferometer displayed a corresponding red shift. The observed spectral shift was used to calculate the amount of refractive index change inscribed by the femtosecond irradiation. For the MZI length of 3.25 mm, and spectral shift of 0.8 nm, the calculated refractive index was found to be 0.00022. The reported results display excellent agreement between theory and experimental findings. Demonstrated method provides simple yet very effective on-site measurement of index change in optical fibers. Since the MZI can be constructed in diverse fiber types, this technique offers flexibility to quantify index change in various optical fibers.

  19. Study on the dose distribution of the mixed field with thermal and epi-thermal neutrons for neutron capture therapy

    International Nuclear Information System (INIS)

    Kobayashi, Tooru; Sakurai, Yoshinori; Kanda, Keiji

    1994-01-01

    Simulation calculations using DOT 3.5 were carried out in order to confirm the characteristics of depth-dependent dose distribution in water phantom dependent on incident neutron energy. The epithermal neutrons mixed to thermal neutron field is effective improving the thermal neutron depth-dose distribution for neutron capture therapy. A feasibility study on the neutron energy spectrum shifter was performed using ANISN-JR for the KUR Heavy Water Facility. The design of the neutron spectrum shifter is feasible, without reducing the performance as a thermal neutron irradiation field. (author)

  20. Computer simulation of nonstationary thermal fields in design and operation of northern oil and gas fields

    Energy Technology Data Exchange (ETDEWEB)

    Vaganova, N. A., E-mail: vna@imm.uran.ru [Institute of Mathematics and Mechanics of Ural Branch of Russian Academy of Sciences, Ekaterinburg (Russian Federation); Filimonov, M. Yu., E-mail: fmy@imm.uran.ru [Ural Federal University, Ekaterinburg, Russia and Institute of Mathematics and Mechanics of Ural Branch of Russian Academy of Sciences, Ekaterinburg (Russian Federation)

    2015-11-30

    A mathematical model, numerical algorithm and program code for simulation and long-term forecasting of changes in permafrost as a result of operation of a multiple well pad of northern oil and gas field are presented. In the model the most significant climatic and physical factors are taken into account such as solar radiation, determined by specific geographical location, heterogeneous structure of frozen soil, thermal stabilization of soil, possible insulation of the objects, seasonal fluctuations in air temperature, and freezing and thawing of the upper soil layer. Results of computing are presented.

  1. Factors affecting thermal infrared images at selected field sites

    International Nuclear Information System (INIS)

    Sisson, J.B.; Ferguson, J.S.

    1993-07-01

    A thermal infrared (TIR) survey was conducted to locate surface ordnance in and around the Naval Ordnance Disposal Area, and a thermal anomaly was found. This report documents studies conducted to identify the position of cause of the thermal anomaly. Also included are results of a long path Fourier transform infrared survey, soil sampling activities, soil gas surveys, and buried heater studies. The results of these studies indicated that the thermal anomaly was caused by a gravel pad, which had thermal properties different than those of the surrounding soil. Results from this investigation suggest that TIR is useful for locating surface objects having a high thermal inertia compared to the surrounding terrain, but TIR is of very limited use for characterizing buried waste or other similar buried objects at the INEL

  2. Toward single-mode random lasing within a submicrometre-sized spherical ZnO particle film

    International Nuclear Information System (INIS)

    Niyuki, Ryo; Fujiwara, Hideki; Sasaki, Keiji; Ishikawa, Yoshie; Koshizaki, Naoto; Tsuji, Takeshi

    2016-01-01

    We had recently reported unique random laser action such as quasi-single-mode and low-threshold lasing from a submicrometre-sized spherical ZnO nanoparticle film with polymer particles as defects. The present study demonstrates a novel approach to realize single-mode random lasing by adjusting the sizes of the defect particles. From the dependence of random lasing properties on defect size, we find that the average number of lasing peaks can be modified by the defect size, while other lasing properties such as lasing wavelengths and thresholds remain unchanged. These results suggest that lasing wavelengths and thresholds are determined by the resonant properties of the surrounding scatterers, while the defect size stochastically determines the number of lasing peaks. Therefore, if we optimize the sizes of the defects and scatterers, we can intentionally induce single-mode lasing even in a random structure (Fujiwara et al 2013 Appl. Phys. Lett. 102 061110). (paper)

  3. Single mode operation in a pulsed Ti:sapphire laser oscillator with a grazing-incidence four-mirror cavity

    CERN Document Server

    Ko, D K; Binks, D J; Gloster, L A W; King, T A

    1998-01-01

    We demonstrate stable single mode operation in a pulsed Ti:sapphire laser oscillator with a novel grazing-incidence four-mirror coupled cavity. This cavity consists of a grating, a gain medium, and four mirrors and, therefore, has a four-arm interferometer configuration. Through the interferometric effect, we could suppress the adjacent modes and obtain stable single mode operation with a bandwidth of < 200 MHz. We also have developed a general analysis of the laser modes and the threshold conditions for configuration and the experimental results agree well with the theoretical predictions.

  4. Single-mode solid-state polymer dye laser fabricated with standard I-line UV lithography

    DEFF Research Database (Denmark)

    Balslev, Søren; Mironov, Andrej; Nilsson, Daniel

    2005-01-01

    We present single-mode solid-state polymer dye lasers fabricated with standard UV lithography. The lasers use a high-order Bragg grating and rely on index-tuning of a photosensitive polymer for waveguiding. The gain medium is Rhodamine 6G.......We present single-mode solid-state polymer dye lasers fabricated with standard UV lithography. The lasers use a high-order Bragg grating and rely on index-tuning of a photosensitive polymer for waveguiding. The gain medium is Rhodamine 6G....

  5. Single-mode Rayleigh-Taylor growth-rate measurements with the OMEGA laser system

    International Nuclear Information System (INIS)

    Knauer, J.P.; Verdon, C.P.; Meyerhofer, D.D.; Boehly, T.R.; Bradley, D.K.; Smalyuk, V.A.; Ofer, D.; McKenty, P.W.; Glendinning, S.G.; Kalantar, D.H.; Watt, R.G.; Gobby, P.L.; Willi, O.; Taylor, R.J.

    1997-01-01

    The results from a series of single-mode Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five to six 351-nm laser beams overlapped with total intensities up to 2.5x10 14 W/cm 2 . Experiments were performed with both 3-ns ramp and 3-ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%endash 7% over a 600-μm-diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using through-foil radiography and was detected with an x-ray framing camera for CH targets with and without a foam buffer. The growth of both 31-μm and 60-μm wavelength perturbations was found to be in good agreement with ORCHID simulations when the experimental details, including noise, were included. The addition of a 30-mg/cc, 100-μm-thick polystyrene foam buffer layer resulted in reduced growth of the 31-μm perturbation and essentially unchanged growth for the 60-μm case when compared to targets without foam. copyright 1997 American Institute of Physics

  6. Single-mode optical waveguides on native high-refractive-index substrates

    Directory of Open Access Journals (Sweden)

    Richard R. Grote

    2016-10-01

    Full Text Available High-refractive-index semiconductor optical waveguides form the basis for modern photonic integrated circuits (PICs. However, conventional methods for achieving optical confinement require a thick lower-refractive-index support layer that impedes large-scale co-integration with electronics and limits the materials on which PICs can be fabricated. To address this challenge, we present a general architecture for single-mode waveguides that confine light in a high-refractive-index material on a native substrate. The waveguide consists of a high-aspect-ratio fin of the guiding material surrounded by lower-refractive-index dielectrics and is compatible with standard top-down fabrication techniques. This letter describes a physically intuitive, semi-analytical, effective index model for designing fin waveguides, which is confirmed with fully vectorial numerical simulations. Design examples are presented for diamond and silicon at visible and telecommunications wavelengths, respectively, along with calculations of propagation loss due to bending, scattering, and substrate leakage. Potential methods of fabrication are also discussed. The proposed waveguide geometry allows PICs to be fabricated alongside silicon CMOS electronics on the same wafer, removes the need for heteroepitaxy in III-V PICs, and will enable wafer-scale photonic integration on emerging material platforms such as diamond and SiC.

  7. Experimental demonstration of single-mode fiber coupling over relatively strong turbulence with adaptive optics.

    Science.gov (United States)

    Chen, Mo; Liu, Chao; Xian, Hao

    2015-10-10

    High-speed free-space optical communication systems using fiber-optic components can greatly improve the stability of the system and simplify the structure. However, propagation through atmospheric turbulence degrades the spatial coherence of the signal beam and limits the single-mode fiber (SMF) coupling efficiency. In this paper, we analyze the influence of the atmospheric turbulence on the SMF coupling efficiency over various turbulences. The results show that the SMF coupling efficiency drops from 81% without phase distortion to 10% when phase root mean square value equals 0.3λ. The simulations of SMF coupling with adaptive optics (AO) indicate that it is inevitable to compensate the high-order aberrations for SMF coupling over relatively strong turbulence. The SMF coupling efficiency experiments, using an AO system with a 137-element deformable mirror and a Hartmann-Shack wavefront sensor, obtain average coupling efficiency increasing from 1.3% in open loop to 46.1% in closed loop under a relatively strong turbulence, D/r0=15.1.

  8. Trapped-ion anomalous diffusion coefficient on the basis of single mode saturation

    International Nuclear Information System (INIS)

    Koshi, Yuji; Hatayama, Akiyoshi; Ogasawara, Masatada.

    1982-03-01

    Expressions of the anomalous diffusion coefficient due to the dissipative trapped ion instability (DTII) are derived for the case with and without the effect of magnetic shear. Derivation is made by taking into account of the single mode saturation of the DTII previously obtained numerically. In the absence of the shear effect, the diffusion coefficient is proportional to #betta#sub(i)a 2 (#betta#sub(i) is the effective collision frequency of the trapped ions and a is the minor radius of a torus) and is much larger than the neoclassical ion heat conductivity. In the presence of the shear effect, the diffusion coefficient is much smaller than the Kadomtsev and Pogutse's value and is the same order of magnitude as the neoclassical ion heat conductivity. Dependences of the diffusion coefficient on the temperature and on the total particle number density are rather complicated due to the additional spectral cut-off, which is introduced to regularize the short wavelength modes in the numerical analysis. (author)

  9. Design and experiments of a linear piezoelectric motor driven by a single mode.

    Science.gov (United States)

    Liu, Zhen; Yao, Zhiyuan; Li, Xiang; Fu, Qianwei

    2016-11-01

    In this contribution, we propose a novel linear piezoelectric motor with a compact stator that is driven by a single mode. The linear piezoelectric motor can realize bidirectional motion by changing the vibration modes of the stator. Finite element analysis is performed to determine the required vibration mode of the stator and obtain the optimal stator structure and dimensions. Furthermore, the trajectories of the driving foot are analyzed with and without consideration of the mechanical contact with the slider. It is shown that the trajectory of the driving foot is an oblique line when disregarding the contact, and the trajectory becomes an oblique ellipse while taking into account the contact. Finally, a prototype of the motor is fabricated based on the results of finite element analysis. The optimization results show that the motor reaches its maximum thrust force of 4.0 kg, maximum thrust-weight ratio of 33.3, maximum unloaded velocity of 385 mm/s under the excitation of Mode-B, and maximum unloaded velocity of 315 mm/s under the excitation of Mode-L.

  10. Role of third-order dispersion in chirped Airy pulse propagation in single-mode fibers

    Science.gov (United States)

    Cai, Wangyang; Wang, Lei; Wen, Shuangchun

    2018-04-01

    The dynamic propagation of the initial chirped Airy pulse in single-mode fibers is studied numerically, special attention being paid to the role of the third-order dispersion (TOD). It is shown that for the positive TOD, the Airy pulse experiences inversion irrespective of the sign of initial chirp. The role of TOD in the dynamic propagation of the initial chirped Airy pulse depends on the combined sign of the group-velocity dispersion (GVD) and the initial chirp. If the GVD and chirp have the opposite signs, the chirped Airy pulse compresses first and passes through a breakdown area, then reconstructs a new Airy pattern with opposite acceleration, with the breakdown area becoming small and the main peak of the new Airy pattern becoming asymmetric with an oscillatory structure due to the positive TOD. If the GVD and chirp have the same signs, the finite-energy Airy pulse compresses to a focal point and then inverses its acceleration, in the case of positive TOD, the distance to the focal point becoming smaller. At zero-dispersion point, the finite-energy Airy pulse inverses to the opposite acceleration at a focal point, with the tight-focusing effect being reduced by initial chirp. Under the effect of negative TOD, the initial chirped Airy pulse disperses and the lobes split. In addition, in the anomalous dispersion region, for strong nonlinearity, the initial chirped Airy pulse splits and enters a soliton shedding regime.

  11. Fidelity of Quantum Teleportation for Single-Mode Squeezed State Light

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jun-Xiang; XIE Chang-De; PENG Kun-Chi

    2005-01-01

    @@ The fidelity of quantum teleportation of a single-mode squeezed state of light is calculated based on the general theory of quantum-mechanical measurement in the Schrodinger picture. It is shown that the criterion for the nonclassical state teleportation is different from that for coherent state. F = 1/2 is no longer the rigorous boundary between classical and quantum teleportation for a squeezed state of light. When the quantum entanglement of an Einstein-Podolsky-Rosen (EPR) beam used for teleportation and the parameters of the system are given,the fidelity depends on the squeezing of the input squeezed state. The higher the squeezing is, the smaller the fidelity is, and the lower the classical limitation of fidelity is. The dependence of the optimum gain for teleporting a squeezed vacuum state upon the EPR entanglement is also calculated. The results obtained provide important references for designing experimental systems of teleporting a non-classical state and judging the quality of the teleported quantum state.

  12. BEND-INDUCED LOSSES IN A SINGLE-MODE MICROSTRUCTURED FIBER WITH A LARGE CORE

    Directory of Open Access Journals (Sweden)

    Y. A. Gatchin

    2015-03-01

    Full Text Available A study of bend-induced losses in a silica-based single-mode microstructured fiber with a core diameter ranging from 20 to 35 microns and increased relative air content in the holey cladding has been conducted. With the use of the equivalent step-index profile method in approximation of waveguide parameters of microstructured fiber (normalized frequency and normalized transverse attenuation constant the effect of bending on the spectral position of the fundamentalmode short-wavelength leakage boundary has been analyzed. Upon measurement of spectral characteristics of attenuation in the considered fibers good accordance of numerical and experimental data has been found out. It is shown that increase of the air content in the holey cladding leads to expansion of the mentioned boundary to lower wavelengths for the value from 150 to 800 nm depending on the core size and bending conditions. A single-transverse-mode propagation is achieved on fiber length of 5-10 meters due to a substantial difference in losses of fundamental and higher-order guided modes attained by bending. Optical losses in all studied samples are less than 10 dB/km at the wavelength λ = 1550 nm. The results of the study can be applied in the design of high-power laser systems having such basic requirements as a relatively large mode spot and high beam quality.

  13. A Novel Technique for Sterilization Using a Power Self-Regulated Single-Mode Microwave Cavity.

    Science.gov (United States)

    Reverte-Ors, Juan D; Pedreño-Molina, Juan L; Fernández, Pablo S; Lozano-Guerrero, Antonio J; Periago, Paula M; Díaz-Morcillo, Alejandro

    2017-06-07

    In this paper, a novel technique to achieve precise temperatures in food sterilization has been proposed. An accurate temperature profile is needed in order to reach a commitment between the total removal of pathogens inside the product and the preservation of nutritional and organoleptic characteristics. The minimal variation of the target temperature in the sample by means of a monitoring and control software platform, allowing temperature stabilization over 100 °C, is the main goal of this work. A cylindrical microwave oven, under pressure conditions and continuous control of the microwave supply power as function of the final temperature inside the sample, has been designed and developed with conditions of single-mode resonance. The uniform heating in the product is achieved by means of sample movement and the self-regulated power control using the measured temperature. Finally, for testing the sterilization of food with this technology, specific biological validation based on Bacillus cereus as a biosensor of heat inactivation has been incorporated as a distribution along the sample in the experimental process to measure the colony-forming units (CFUs) for different food samples (laboratory medium, soup, or fish-based animal by-products). The obtained results allow the validation of this new technology for food sterilization with precise control of the microwave system to ensure the uniform elimination of pathogens using high temperatures.

  14. A Novel Technique for Sterilization Using a Power Self-Regulated Single-Mode Microwave Cavity

    Directory of Open Access Journals (Sweden)

    Juan D. Reverte-Ors

    2017-06-01

    Full Text Available In this paper, a novel technique to achieve precise temperatures in food sterilization has been proposed. An accurate temperature profile is needed in order to reach a commitment between the total removal of pathogens inside the product and the preservation of nutritional and organoleptic characteristics. The minimal variation of the target temperature in the sample by means of a monitoring and control software platform, allowing temperature stabilization over 100 °C, is the main goal of this work. A cylindrical microwave oven, under pressure conditions and continuous control of the microwave supply power as function of the final temperature inside the sample, has been designed and developed with conditions of single-mode resonance. The uniform heating in the product is achieved by means of sample movement and the self-regulated power control using the measured temperature. Finally, for testing the sterilization of food with this technology, specific biological validation based on Bacillus cereus as a biosensor of heat inactivation has been incorporated as a distribution along the sample in the experimental process to measure the colony-forming units (CFUs for different food samples (laboratory medium, soup, or fish-based animal by-products. The obtained results allow the validation of this new technology for food sterilization with precise control of the microwave system to ensure the uniform elimination of pathogens using high temperatures.

  15. Bending , Heating and Pressure Effects of He-Ne Laserin Single Mode Fiber

    Directory of Open Access Journals (Sweden)

    Nizar Salim Shnan

    2017-12-01

    Full Text Available In this paper a single mode fiber have been chosen with a refractive index (1.50 to the core, and (1.485 to the cladding, with length of (2 m. It was exposed this optical fiber to a bending with different diameters, and to a different temperatures as well as pressure due to putting different weights to study dispersion phenomenon which affects on a pulse shape that travels in optical fiber. Experimental results explain when a bending diameter for an optical fiber increases it will decrease the dispersion and pulse shape will approximate from a Gaussian shape , and the increasing in temperature will increasing  the attenuation in the pulse transfer through the optical fiber .                                                                                                 But when increasing pressure, the dispersion will increases and the pulse shape will be distorted

  16. Mould insert fabrication of a single-mode fibre connector alignment structure optimized by justified partial metallization

    International Nuclear Information System (INIS)

    Wissmann, Markus; Barié, Nicole; Guttmann, Markus; Schneider, Marc; Kolew, Alexander; Besser, Heino; Pfleging, Wilhelm; Hofmann, Andreas; Van Erps, Jürgen; Beri, Stefano; Watté, Jan

    2015-01-01

    For mass production of multiscale-optical components, microstructured moulding tools are needed. Metal tools are used for hot embossing or injection moulding of microcomponents made of a thermoplastic polymer. Microstructures with extremely tight specifications, e.g. low side wall roughness and high aspect ratios are generally made by lithographic procedures such as x-ray lithography or deep proton writing. However, these processes are unsuitable for low-cost mass production. An alternative manufacturing method of moulding tools has been developed at the Karlsruhe Institute of Technology (KIT). This article describes a mould insert fabrication and a new replication process for self-centring fibre alignment structures for low loss field installable single-mode fibre connectors, developed and fabricated by the Vrije Universiteit Brussel (VUB) in collaboration with TE Connectivity. These components are to be used in fibre-to-the-home networks and support the deployment and maintenance of fibre optic links. The special feature of this particular fibre connector is a self-centring fibre alignment, achieved by means of a through hole with deflectable cantilevers acting as micro-springs. The particular challenge is the electroforming of through holes with a centre hole diameter smaller than 125 µm. The fibre connector structure is prototyped by deep proton writing in polymethylmethacrylate and used as a sacrificial part. Using joining, physical vapour deposition and electroforming technology, a negative copy of the prototyped connector is transferred into nickel to be used as a moulding tool. The benefits of this replication technique are a rapid and economical fabrication of moulding tools with high-precision microstructures and a long tool life. With these moulding tools low-cost mass production is possible. We present the manufacturing chain we have established. Each individual manufacturing step of the mould insert fabrication will be shown in this report. The

  17. Single-mode regime in large-mode-area rare-earth-doped rod-type PCFs

    DEFF Research Database (Denmark)

    Poli, F.; Cucinotta, A.; Passaro, D.

    2009-01-01

    In this paper, large-mode-area, double-cladding, rare-earth-doped photonic crystal fibers are investigated in order to understand how the refractive index distribution and the mode competition given by the amplification can assure single-mode propagation. Fibers with different core diameters, i...

  18. Light coupling and distribution for Si3N4/SiO2 integrated multichannel single-mode sensing system

    Science.gov (United States)

    Kaźmierczak, Andrzej; Dortu, Fabian; Schrevens, Olivier; Giannone, Domenico; Bouville, David; Cassan, Eric; Gylfason, Kristinn B.; Sohlström, Hans; Sanchez, Benito; Griol, Amadeu; Hill, Daniel

    2009-01-01

    We present an efficient and highly alignment-tolerant light coupling and distribution system for a multichannel Si3N4/SiO2 single-mode photonics sensing chip. The design of the input and output couplers and the distribution splitters is discussed. Examples of multichannel data obtained with the system are given.

  19. Anisotropic anti-resonant elements gives broadband single-mode low-loss hollow-core fibers

    DEFF Research Database (Denmark)

    Habib, Selim; Bang, Ole; Bache, Morten

    2016-01-01

    Hollow-core fibers with node-free anisotropic anti-resonant elements give broadband low-loss fibers that are also single-moded. At 1.06 μm silica-based fiber designs show higher-order-mode extinction-ratio >1000 and losses below 10 dB/km over a broad wavelength range....

  20. Single-mode temperature and polarisation-stable high-speed 850nm vertical cavity surface emitting lasers

    International Nuclear Information System (INIS)

    Nazaruk, D E; Blokhin, S A; Maleev, N A; Bobrov, M A; Pavlov, M M; Kulagina, M M; Vashanova, K A; Zadiranov, Yu M; Ustinov, V M; Kuzmenkov, A G; Vasil'ev, A P; Gladyshev, A G; Blokhin, A A; Salut, 7 Larina Str, N Novgorod, 603950 (Russian Federation))" data-affiliation=" (JSV Salut, 7 Larina Str, N Novgorod, 603950 (Russian Federation))" >Fefelov, A G

    2014-01-01

    A new intracavity-contacted design to realize temperature and polarization-stable high-speed single-mode 850 nm vertical cavity surface emitting lasers (VCSELs) grown by molecular-beam epitaxy is proposed. Temperature dependences of static and dynamic characteristics of the 4.5 pm oxide aperture InGaAlAs VCSEL were investigated in detail. Due to optimal gain-cavity detuning and enhanced carrier localization in the active region the threshold current remains below 0.75 mA for the temperature range within 20-90°C, while the output power exceeds 1 mW up to 90°C. Single-mode operation with side-mode suppression ratio higher than 30 dB and orthogonal polarization suppression ratio more than 18 dB was obtained in the whole current and temperature operation range. Device demonstrates serial resistance less than 250 Ohm, which is rather low for any type of single-mode short- wavelength VCSELs. VCSEL demonstrates temperature robust high-speed operation with modulation bandwidth higher than 13 GHz in the entire temperature range of 20-90°C. Despite high resonance frequency the high-speed performance of developed VCSELs was limited by the cut-off frequency of the parasitic low pass filter created by device resistances and capacitances. The proposed design is promising for single-mode high-speed VCSEL applications in a wide spectral range

  1. Particle Production and Effective Thermalization in Inhomogeneous Mean Field Theory

    NARCIS (Netherlands)

    Aarts, G.; Smit, J.

    2000-01-01

    As a toy model for dynamics in nonequilibrium quantum field theory we consider the abelian Higgs model in 1+1 dimensions with fermions. In the approximate dynamical equations, inhomogeneous classical (mean) Bose fields are coupled to quantized fermion fields, which are treated with a mode function

  2. A comparative study of the single-mode Richtmyer-Meshkov instability

    Science.gov (United States)

    Bai, X.; Deng, X.-L.; Jiang, L.

    2017-11-01

    In this work, the single-mode Richtmyer-Meshkov instability is studied numerically to find a reasonable nonlinear theoretical model which can be applied to predict the interface evolution from the linear stage to the early nonlinear stage. The cut-cell-based sharp-interface methods MuSiC+ (Chang et al. in J Comput Phys 242:946-990, 2013) and CCGF (Bai and Deng in Adv Appl Math Mech 9(5):1052-1075, 2017) are applied to generate numerical results for comparisons. Classical Air-SF6 and Air-Helium conditions are applied in this study, and initial amplitude and Atwood number are varied for comparison. Comparisons to the simulation results from the literature show the applicability of MuSiC+ and CCGF. Comparisons to the nonlinear theoretical models show that ZS (Zhang and Sohn in Phys Lett A 212:149-155, 1996; Phys Fluids 9:1106-1124, 1997), SEA (Sadot et al. in Phys Rev Lett 80:1654-1657, 1998), and DR (Dimonte and Ramaprabhu in Phys Fluids 22:014104, 2010) models are valid for both spike and bubble growth rates, and MIK (Mikaelian in Phys Rev E 67:026319, 2003) and ZG (Zhang and Guo in J Fluid Mech 786:47-61, 2016) models are valid for bubble growth rate, when the initial perturbation is small and the Atwood number is low, but only the DR model is applicable for both spike and bubble growth rates when the initial perturbation amplitude and the Atwood number are large. A new term of non-dimensional initial perturbation amplitude is presented and multiplied to the DR model to get a unified fitted DR model, which gives consistent results to the simulation ones for small and large initial amplitudes.

  3. Single-mode, Rayleigh-Taylor growth-rate measurements on the OMEGA laser system

    International Nuclear Information System (INIS)

    Knauer, J. P.; Betti, R.; Bradley, D. K.; Boehly, T. R.; Collins, T. J. B.; Goncharov, V. N.; McKenty, P. W.; Meyerhofer, D. D.; Smalyuk, V. A.; Verdon, C. P.

    2000-01-01

    The results from a series of single-mode, Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five or six 351 nm laser beams overlapped with total intensities up to 2.5x10 14 W/cm 2 . Experiments were performed with both 3 ns ramp and 3 ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%-7% over a 600 μm diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using throughfoil radiography and was detected with an x-ray framing camera for CH targets. Two-dimensional (2-D) hydrodynamic simulations (ORCHID) [R. L. McCrory and C. P. Verdon, in Inertial Confinement Fusion (Editrice Compositori, Bologna, 1989), pp. 83-124] of the growth of 20, 31, and 60 μm wavelength perturbations were in good agreement with the experimental data when the experimental details, including noise, were included. The amplitude of the simulation optical depth is in good agreement with the experimental optical depth; therefore, great care must be taken when the growth rates are compared to dispersion formulas. Since the foil's initial condition just before it is accelerated is not that of a uniformly compressed foil, the optical density measurement does not accurately reflect the amplitude of the ablation surface but is affected by the initial nonuniform density profile. (c) 2000 American Institute of Physics

  4. Single-mode, Rayleigh-Taylor growth-rate measurements on the OMEGA laser system

    Energy Technology Data Exchange (ETDEWEB)

    Knauer, J. P. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Betti, R. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Bradley, D. K. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Boehly, T. R. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Collins, T. J. B. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Goncharov, V. N. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); McKenty, P. W. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Meyerhofer, D. D. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Smalyuk, V. A. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Verdon, C. P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] (and others)

    2000-01-01

    The results from a series of single-mode, Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five or six 351 nm laser beams overlapped with total intensities up to 2.5x10{sup 14} W/cm{sup 2}. Experiments were performed with both 3 ns ramp and 3 ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%-7% over a 600 {mu}m diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using throughfoil radiography and was detected with an x-ray framing camera for CH targets. Two-dimensional (2-D) hydrodynamic simulations (ORCHID) [R. L. McCrory and C. P. Verdon, in Inertial Confinement Fusion (Editrice Compositori, Bologna, 1989), pp. 83-124] of the growth of 20, 31, and 60 {mu}m wavelength perturbations were in good agreement with the experimental data when the experimental details, including noise, were included. The amplitude of the simulation optical depth is in good agreement with the experimental optical depth; therefore, great care must be taken when the growth rates are compared to dispersion formulas. Since the foil's initial condition just before it is accelerated is not that of a uniformly compressed foil, the optical density measurement does not accurately reflect the amplitude of the ablation surface but is affected by the initial nonuniform density profile. (c) 2000 American Institute of Physics.

  5. Toward photostable multiplex analyte detection on a single mode planar optical waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Mukundan, Harshini [Los Alamos National Laboratory; Xei, Hongshi [Los Alamos National Laboratory; Anderson, Aaron S [Los Alamos National Laboratory; Grace, Wynne K [Los Alamos National Laboratory; Martinez, Jennifer S [NON LANL; Swanson, Basil [Los Alamos National Laboratory

    2009-01-01

    We have developed a waveguide-based optical biosensor for the sensitive and specific detection of biomarkers associated with disease. Our technology combines the superior optical properties of single-mode planar waveguides, the robust nature of functionalized self-assembled monolayer sensing films and the specificity of fluorescence sandwich immunoassays to detect biomarkers in complex biological samples such as serum, urine and sputum. We have previously reported the adaptation of our technology to the detection of biomarkers associated with breast cancer and anthrax. However, these approaches primarily used phospholipid bilayers as the functional film and organic dyes (ex: AlexaFluors) as the fluorescence reporter. Organic dyes are easily photodegraded and are not amenable to multiplexing because of their narrow Stokes' shift. Here we have developed strategies for conjugation of the detector antibodies with quantum dots for use in a multiplex detection platform. We have previously evaluated dihydroxylipoic acid quantum dots for the detection of a breast cancer biomarker. In this manuscript, we investigate the detection of the Bacillus anthracis protective antigen using antibodies conjugated with polymer-coated quantum dots. Kinetics of binding on the waveguide-based biosensor is reported. We compare the sensitivity of quantum dot labeled antibodies to those labeled with AlexaFluor and demonstrate the photostability of the former in our assay platform. In addition, we compare sulfydryl labeling of the antibody in the hinge region to that of nonspecific amine labeling. This is but the first step in developing a multiplex assay for such biomarkers on our waveguide platform.

  6. Effects of Anisotropic Thermal Conductivity in Magnetohydrodynamics Simulations of a Reversed-Field Pinch

    International Nuclear Information System (INIS)

    Onofri, M.; Malara, F.; Veltri, P.

    2010-01-01

    A compressible magnetohydrodynamics simulation of the reversed-field pinch is performed including anisotropic thermal conductivity. When the thermal conductivity is much larger in the direction parallel to the magnetic field than in the perpendicular direction, magnetic field lines become isothermal. As a consequence, as long as magnetic surfaces exist, a temperature distribution is observed displaying a hotter confined region, while an almost uniform temperature is produced when the magnetic field lines become chaotic. To include this effect in the numerical simulation, we use a multiple-time-scale analysis, which allows us to reproduce the effect of a large parallel thermal conductivity. The resulting temperature distribution is related to the existence of closed magnetic surfaces, as observed in experiments. The magnetic field is also affected by the presence of an anisotropic thermal conductivity.

  7. Studies on thermal fields in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Gopalakrishna, V.V.; Rao, A.S.

    of Science and Technology. The main objective of the program is routine monitoring of the upper ocean thermal structure along selected shipping lanes in the seas around India on annual and interannual time scales. Utilizing the near bi-monthly XBT data along...

  8. Virasoro conformal blocks and thermality from classical background fields

    Energy Technology Data Exchange (ETDEWEB)

    Fitzpatrick, A. Liam [Stanford Institute for Theoretical Physics, Stanford University,Via Pueblo, Stanford, CA 94305 (United States); SLAC National Accelerator Laboratory,Sand Hill Road, Menlo Park, CA 94025 (United States); Kaplan, Jared [Department of Physics and Astronomy, Johns Hopkins University,Charles Street, Baltimore, MD 21218 (United States); Walters, Matthew T. [Department of Physics, Boston University,Commonwealth Avenue, Boston, MA 02215 (United States)

    2015-11-30

    We show that in 2d CFTs at large central charge, the coupling of the stress tensor to heavy operators can be re-absorbed by placing the CFT in a non-trivial background metric. This leads to a more precise computation of the Virasoro conformal blocks between heavy and light operators, which are shown to be equivalent to global conformal blocks evaluated in the new background. We also generalize to the case where the operators carry U(1) charges. The refined Virasoro blocks can be used as the seed for a new Virasoro block recursion relation expanded in the heavy-light limit. We comment on the implications of our results for the universality of black hole thermality in AdS{sub 3}, or equivalently, the eigenstate thermalization hypothesis for CFT{sub 2} at large central charge.

  9. Consistent effects of a major QTL for thermal resistance in field-released Drosophila melanogaster

    DEFF Research Database (Denmark)

    Loeschcke, Volker; Kristensen, Torsten Nygård; Norry, Fabian M

    2011-01-01

    Molecular genetic markers can be used to identify quantitative trait loci (QTL) for thermal resistance and this has allowed characterization of a major QTL for knockdown resistance to high temperature in Drosophila melanogaster. The QTL showed trade-off associations with cold resistance under lab...... of field fitness at different environmental temperatures with genotypic variation in a QTL for thermal tolerance. Graphical abstract...

  10. High-field thermal transports properties of REBCO coated conductors

    CERN Document Server

    Bonura, M

    2015-01-01

    The use of REBCO coated conductors is envisaged for many applications, extending from power cables to high-field magnets. Whatever the case, thermal properties of REBCO tapes play a key role for the stability of superconducting devices. In this work, we present the first study on the longitudinal thermal conductivity (k) of REBCO coated conductors in magnetic fields up to 19 T applied both parallelly and perpendicularly to the thermal-current direction. Copper-stabilized tapes from six industrial manufacturers have been investigated. We show that zero-field k of coated conductors can be calculated with an accuracy of ‡ 15% from the residual resistivity ratio of the stabilizer and the Cu/non-Cu ratio. Measurements performed at high fields have allowed us to evaluate the consistency of the procedures generally used for estimating in-field k in the framework of the Wiedemann-Franz law from an electrical characterization of the materials. In-field data are intended to provide primary ingredients for the ...

  11. Complementary variational principle method applied to thermal conductivities of a plasma in a uniform magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Sehgal, A K; Gupta, S C [Punjabi Univ., Patiala (India). Dept. of Physics

    1982-12-14

    The complementary variational principles method (CVP) is applied to the thermal conductivities of a plasma in a uniform magnetic field. The results of computations show that the CVP derived results are very useful.

  12. Design and prototyping of self-centering optical single-mode fiber alignment structures

    International Nuclear Information System (INIS)

    Ebraert, Evert; Gao, Fei; Thienpont, Hugo; Van Erps, Jürgen; Beri, Stefano; Watté, Jan

    2016-01-01

    The European Commission’s goal of providing each European household with at least a 30 Mb s −1 Internet connection by 2020 would be facilitated by a widespread deployment of fibre-to-the-home, which would in turn be sped up by the development of connector essential components, such as high-precision alignment features. Currently, the performance of state-of-the-art physical contact optical fiber connectors is limited by the tolerance on the cladding of standard telecom-grade single-mode fiber (SMF), which is typically smaller than  ±1 μ m. We propose to overcome this limit by developing micro-spring-based self-centering alignment structures (SCAS) for SMF-connectors. We design these alignment structures with robustness and low-cost replication in mind, allowing for large-scale deployment. Both theoretical and finite element analysis (FEA) models are used to determine the optimal dimensions of the beams of which the micro-springs of the SCAS are comprised. Two topologies of the SCAS, consisting of three and four micro-springs respectively, are investigated for two materials: polysulfone (PSU) and polyetherimide (PEI). These materials hold great potential for high-performance fiber connectors while being compatible with low-cost production and with the harsh environmental operation conditions of those connectors. The theory and FEA agree well (<3% difference) for a simple micro-spring. When including a pedestal on the micro-spring (to bring it further away from the fiber) and for shorter spring lengths the agreement worsens. This is due to spring compression effects not being taken into account in our theoretical model. Prototypes are successfully fabricated using deep proton writing and subsequently characterized. The controlled insertion of an SMF in the SCAS is investigated and we determine that a force of 0.11 N is required. The fiber insertion also causes an out-of-plane deformation of the micro-springs in the SCAS of about 7 μ m, which is no

  13. Magnetic field of Mercury and models of thermal evolution

    International Nuclear Information System (INIS)

    Sharpe, H.N.; Strangway, D.W.

    1976-01-01

    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

  14. The field investigation on thermal comfort of tent in early autumn of Tianjin

    Directory of Open Access Journals (Sweden)

    Yang Hao

    2016-01-01

    Full Text Available In a university campus in Tianjin, four tents were set up to investigate the thermal environment and thermal comfort. Both the field investigation and questionnaires were adopted in this experiment. Two hundred people were investigated, and two hundred questionnaires were gotten. The results show that the thermal comfort zone of officers and soldiers is 24°C to 28°C in early fall, it is a wide range. There is a big error between the PMV index and the actual survey results, PMV calculation index is not accurate in tents environment. The results will have a significant effect on improving the thermal comfort of tents..

  15. Modelling of thermal field and point defect dynamics during silicon single crystal growth using CZ technique

    Science.gov (United States)

    Sabanskis, A.; Virbulis, J.

    2018-05-01

    Mathematical modelling is employed to numerically analyse the dynamics of the Czochralski (CZ) silicon single crystal growth. The model is axisymmetric, its thermal part describes heat transfer by conduction and thermal radiation, and allows to predict the time-dependent shape of the crystal-melt interface. Besides the thermal field, the point defect dynamics is modelled using the finite element method. The considered process consists of cone growth and cylindrical phases, including a short period of a reduced crystal pull rate, and a power jump to avoid large diameter changes. The influence of the thermal stresses on the point defects is also investigated.

  16. Kadanoff-Baym Approach to Thermalization of Quantum Fields

    International Nuclear Information System (INIS)

    Nishiyama, Akihiro; Hatta, Yoshitaka

    2013-01-01

    Numerical results of nonequilibrium field theory are shown for O(N) sealer model in 2+1 dimensions with longitudinal expansion. We adopt Next-to-Leading Order of 1/N expansion of self energy with background classical fields to cover all of time evolution of instability. We show differences between quantum dynamics and classical statistical approximation in strongly coupled regimes. As a result we show that we can achieve Boltzmann tail of the final distribution function only in quantum dynamics

  17. Particle-in-cell simulations on spontaneous thermal magnetic field fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Simões, F. J. R. Jr.; Pavan, J. [Instituto de Física e Matemática, UFPel, Pelotas, RS (Brazil); Gaelzer, R.; Ziebell, L. F. [Instituto de Física, UFRGS, Porto Alegre, RS (Brazil); Yoon, P. H. [Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States)

    2013-10-15

    In this paper an electromagnetic particle code is used to investigate the spontaneous thermal emission. Specifically we perform particle-in-cell simulations employing a non-relativistic isotropic Maxwellian particle distribution to show that thermal fluctuations are related to the origin of spontaneous magnetic field fluctuation. These thermal fluctuations can become seed for further amplification mechanisms and thus be considered at the origin of the cosmological magnetic field, at microgauss levels. Our numerical results are in accordance with theoretical results presented in the literature.

  18. Low Field Magnetic and Thermal Hysteresis in Antiferromagnetic Dysprosium

    Directory of Open Access Journals (Sweden)

    Iuliia Liubimova

    2017-06-01

    Full Text Available Magnetic and thermal hysteresis (difference in magnetic properties on cooling and heating have been studied in polycrystalline Dy (dysprosium between 80 and 250 K using measurements of the reversible Villari effect and alternating current (AC susceptibility. We argue that measurement of the reversible Villari effect in the antiferromagnetic phase is a more sensitive method to detect magnetic hysteresis than the registration of conventional B(H loops. We found that the Villari point, recently reported in the antiferromagnetic phase of Dy at 166 K, controls the essential features of magnetic hysteresis and AC susceptibility on heating from the ferromagnetic state: (i thermal hysteresis in AC susceptibility and in the reversible Villari effect disappears abruptly at the temperature of the Villari point; (ii the imaginary part of AC susceptibility is strongly frequency dependent, but only up to the temperature of the Villari point; (iii the imaginary part of the susceptibility drops sharply also at the Villari point. We attribute these effects observed at the Villari point to the disappearance of the residual ferromagnetic phase. The strong influence of the Villari point on several magnetic properties allows this temperature to be ranked almost as important as the Curie and Néel temperatures in Dy and likely also for other rare earth elements and their alloys.

  19. Investigation of single-mode and multi-mode hydromagnetic Rayleigh-Taylor instability in planar geometry

    International Nuclear Information System (INIS)

    Roderick, N.F.; Cochrane, K.; Douglas, M.R.

    1998-01-01

    Previous investigations carried out to study various methods of seeding the hydromagnetic Rayleigh-Taylor instability in magnetohydrodynamic simulations showed features similar to those seen in hydrodynamic calculations. For periodic single-mode initiations the results showed the appearance of harmonics as the single modes became nonlinear. For periodic multi-mode initiations new modes developed that indicated the presence of mode coupling. The MHD simulations used parameters of the high velocity large radius z-pinch experiments performed in the Z-accelerator at Sandia National Laboratories. The cylindrical convergent geometry and variable acceleration of these configurations made comparison with analytic, developed for planar geometry with constant acceleration, difficult. A set of calculations in planar geometry using constant current to produce acceleration and parameters characteristic of the cylindrical implosions has been performed to allow a better comparison. Results of these calculations, comparison with analytic theory, and comparison with the cylindrical configuration calculations will be discussed

  20. Single mode step-index polymer optical fiber for humidity insensitive high temperature fiber Bragg grating sensors

    DEFF Research Database (Denmark)

    Woyessa, Getinet; Fasano, Andrea; Stefani, Alessio

    2016-01-01

    We have fabricated the first single-mode step-index and humidity insensitive polymer optical fiber operating in the 850 nm wavelength ranges. The step-index preform is fabricated using injection molding, which is an efficient method for cost effective, flexible and fast preparation of the fiber...... preform. The fabricated single-mode step-index (SI) polymer optical fiber (POF) has a 4.8µm core made from TOPAS grade 5013S-04 with a glass transition temperature of 134°C and a 150 µm cladding made from ZEONEX grade 480R with a glass transition temperature of 138°C. The key advantages of the proposed...... SIPOF are low water absorption, high operating temperature and chemical inertness to acids and bases and many polar solvents as compared to the conventional poly-methyl-methacrylate (PMMA) and polystyrene based POFs. In addition, the fiber Bragg grating writing time is short compared to microstructured...

  1. Sub-micrometre accurate free-form optics by three-dimensional printing on single-mode fibres

    Science.gov (United States)

    Gissibl, Timo; Thiele, Simon; Herkommer, Alois; Giessen, Harald

    2016-01-01

    Micro-optics are widely used in numerous applications, such as beam shaping, collimation, focusing and imaging. We use femtosecond 3D printing to manufacture free-form micro-optical elements. Our method gives sub-micrometre accuracy so that direct manufacturing even on single-mode fibres is possible. We demonstrate the potential of our method by writing different collimation optics, toric lenses, free-form surfaces with polynomials of up to 10th order for intensity beam shaping, as well as chiral photonic crystals for circular polarization filtering, all aligned onto the core of the single-mode fibres. We determine the accuracy of our optics by analysing the output patterns as well as interferometrically characterizing the surfaces. We find excellent agreement with numerical calculations. 3D printing of microoptics can achieve sufficient performance that will allow for rapid prototyping and production of beam-shaping and imaging devices. PMID:27339700

  2. The use of Lorentz group formalism in solving polarization effects of a birefringent single mode optical fiber

    International Nuclear Information System (INIS)

    Ishiekwene, G.C.; Brown, C.S.; Mensah, S.Y.; Bak, A.E.

    2000-07-01

    A theoretical analysis on the polarization effects of a light beam propagating in a birefringent single-mode fiber is presented. We derive a system of differential equations representing the evolution of Stokes parameters and illustrate their application to polarization effects in a straight birefringent single mode optical fiber. The solutions to the set of equations are obtained using specifically the methods of the unified formalism for polarization optics which adopt the use of the Stokes-Mueller equation and the Lorentz group to model polarization phenomena in media such as optical fibers. The analytical results presented using this approach are identical to results obtained from other conventional methods. We observe the characteristic exponential decrease in the total intensity of the input light due to attenuation by the fiber. (author)

  3. Electrohydrodynamic fibrillation governed enhanced thermal transport in dielectric colloids under a field stimulus.

    Science.gov (United States)

    Dhar, Purbarun; Maganti, Lakshmi Sirisha; Harikrishnan, A R

    2018-05-30

    Electrorheological (ER) fluids are known to exhibit enhanced viscous effects under an electric field stimulus. The present article reports the hitherto unreported phenomenon of greatly enhanced thermal conductivity in such electro-active colloidal dispersions in the presence of an externally applied electric field. Typical ER fluids are synthesized employing dielectric fluids and nanoparticles and experiments are performed employing an in-house designed setup. Greatly augmented thermal conductivity under a field's influence was observed. Enhanced thermal conduction along the fibril structures under the field effect is theorized as the crux of the mechanism. The formation of fibril structures has also been experimentally verified employing microscopy. Based on classical models for ER fluids, a mathematical formalism has been developed to predict the propensity of chain formation and statistically feasible chain dynamics at given Mason numbers. Further, a thermal resistance network model is employed to computationally predict the enhanced thermal conduction across the fibrillary colloid microstructure. Good agreement between the mathematical model and the experimental observations is achieved. The domineering role of thermal conductivity over relative permittivity has been shown by proposing a modified Hashin-Shtrikman (HS) formalism. The findings have implications towards better physical understanding and design of ER fluids from both 'smart' viscoelastic as well as thermally active materials points of view.

  4. Single-mode Brillouin fiber laser passively stabilized at resonance frequency with self-injection locked pump laser

    International Nuclear Information System (INIS)

    Spirin, V V; Lopez-Mercado, C A; Megret, P; Fotiadi, A A

    2012-01-01

    We demonstrate a single-mode Brillouin fiber ring laser, which is passively stabilized at pump resonance frequency by using self-injection locking of semiconductor pump laser. Resonance condition for Stokes radiation is achieved by length fitting of Brillouin laser cavity. The laser generate single-frequency Stokes wave with linewidth less than 0.5 kHz using approximately 17-m length cavity

  5. Single-mode optical fiber design with wide-band ultra low bending-loss for FTTH application.

    Science.gov (United States)

    Watekar, Pramod R; Ju, Seongmin; Han, Won-Taek

    2008-01-21

    We propose a new design of a single-mode optical fiber (SMF) which exhibits ultra low bend sensitivity over a wide communication band (1.3 microm to 1.65 microm). A five-cladding fiber structure has been proposed to minimize the bending loss, estimated to be as low as 4.4x10(-10) dB/turn for the bend radius of 10 mm.

  6. Transmutation of Minor Actinide in well thermalized neutron field and application of advanced neutron source (ANS)

    International Nuclear Information System (INIS)

    Iwasaki, Tomohiko; Hirakawa, Naohiro

    1995-01-01

    Transmutation of Minor Actinide (MA) in a well thermalized neutron field was studied. Since MA nuclides have large effective cross sections in the well thermalized neutron field, the transmutation in the well thermalized neutron field has an advantage of high transmutation rate. However, the transmutation rate largely decreases by accumulation of 246 Cm when MA is transmuted only in the well thermalized neutron field for a long period. An acceleration method of burn-up of 246 Cm was studied. High transmutation rate can be obtained by providing a neutron field with high flux in the energy region between 1 and 100 eV. Two stage transmutation using the well thermalized neutron field and this field can transmute MA rapidly. The applicability of the Advanced Neutron Source (ANS) to the transmutation of MA was examined for a typical MA with the composition in the high-level waste generated in the conventional PWR. If the ANS is applied without changing the fuel inventory, the amount of MA which corresponds to that produced by a conventional 1,175 MWe PWR in one year can be transmuted by the ANS in one year. Furthermore, the amount of the residual can be reduced to about 1g (10 -5 of the initial MA weight) by continuing the transmutation for 5 years owing to the two stage transmutation. (author)

  7. Simulation of Temperature Field in HDPE Pipe Thermal Welding

    Directory of Open Access Journals (Sweden)

    LIU Li-jun

    2017-04-01

    Full Text Available For high density polyethylene pipe connection,welding technology is the key of the high density engineering plastic pressure pipe safety. And the temperature distribution in the welding process has a very important influence on the welding quality. Polyethylene pipe weld joints of one dimensional unsteady overall heat transfer model is established by MARC software and simulates temperature field and stress field distribution of the welding process,and the thermocouple temperature automatic acquisition system of welding temperature field changes were detected,and compared by simulation and experiment .The results show that,at the end of the heating,the temperature of the pipe does not reach the maximum,but reached the maximum at 300 s,which indicates that the latent heat of phase change in the process of pressure welding. In the process of pressure welding, the axial stress of the pipe is gradually changed from tensile stress to compressive stress.

  8. Thermal pulse measurements of space charge distributions under an applied electric field in thin films

    International Nuclear Information System (INIS)

    Zheng, Feihu; An, Zhenlian; Zhang, Yewen; Liu, Chuandong; Lin, Chen; Lei, Qingquan

    2013-01-01

    The thermal pulse method is a powerful method to measure space charge and polarization distributions in thin dielectric films, but a complicated calibration procedure is necessary to obtain the real distribution. In addition, charge dynamic behaviour under an applied electric field cannot be observed by the classical thermal pulse method. In this work, an improved thermal pulse measuring system with a supplemental circuit for applying high voltage is proposed to realize the mapping of charge distribution in thin dielectric films under an applied field. The influence of the modified measuring system on the amplitude and phase of the thermal pulse response current are evaluated. Based on the new measuring system, an easy calibration approach is presented with some practical examples. The newly developed system can observe space charge evolution under an applied field, which would be very helpful in understanding space charge behaviour in thin films. (paper)

  9. Over 19 W Single-Mode 1545 nm Er,Yb Codoped All-Fiber Laser

    Directory of Open Access Journals (Sweden)

    Jiadong Wu

    2017-01-01

    Full Text Available We report a high-power cladding-pumped Er,Yb codoped all-fiber laser with truly single transverse mode output. The fiber laser is designed to operate at 1545 nm by the use of a pair of fiber Bragg gratings (FBGs to lock and narrow the output spectrum, which can be very useful in generating the eye-safe ~1650 nm laser emission through the Stimulated Raman Scattering (SRS in silica fibers that is of interest in many applications. Two pieces of standard single-mode fibers are inserted into the laser cavity and output port to guarantee the truly single-mode output as well as good compatibility with other standard fiber components. We have obtained a maximum output power of 19.2 W at 1544.68 nm with a FWHM spectral width of 0.08 nm, corresponding to an average overall slope efficiency of 31.9% with respect to the launched pump power. This is, to the best of our knowledge, the highest output power reported from simple all-fiber single-mode Er,Yb codoped laser oscillator architecture.

  10. Single-mode distributed feedback laser operation with no dependence on the morphology of the gain medium

    Energy Technology Data Exchange (ETDEWEB)

    Umar, Muhammad [Department of Energy Systems Research, Ajou University, Suwon (Korea, Republic of); Min, Kyungtaek [Department of Energy Systems Research, Ajou University, Suwon (Korea, Republic of); Inter-university Semiconductor Research Center, Seoul National University (Korea, Republic of); Jeon, Heonsu [Department of Physics and Astronomy, Seoul National University (Korea, Republic of); Kim, Sunghwan [Department of Energy Systems Research, Ajou University, Suwon (Korea, Republic of); Department of Physics, Ajou University, Suwon (Korea, Republic of)

    2017-06-15

    Organic distributed feedback (DFB) lasers can be useful photonic tools for biological applications where the roles of organic materials are important, because highly coherent single mode emission with broad tuning range can be obtained. However, the formulaic structures of organic lasers, and the uses of gain media as resonators themselves, are not suitable for inducing laser emission from irregular shaped gain media, such as dye-staining cells and tissues. Here, we report a reusable photonic template comprising an exceedingly thin and discrete titanium dioxide (TiO{sub 2}) layer on a one-dimensional (1D) quartz grating to induce single mode DFB lasing from a variety of states of optical gain media. Using the same template, the external gain media of optically thick and thin casted film, liquid, and a free-standing thick film reveal single mode lasing with reliable performance. Numerical simulations demonstrate that the 25-nm thick TiO{sub 2} disconnected grating lines support a spatially confined DFB mode in the vertical direction, even under no index difference between superstrate and substrate. Additionally, not using the typical waveguide gain layer promises high sensitivity and detection limit in refractometric sensing. These results suggest that the photonic structure may serve as a versatile sensing platform for bioapplications. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    International Nuclear Information System (INIS)

    Hodges, C.S.

    1999-03-01

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

  12. Thermal field theory in a layer: Applications of thermal field theory methods to the propagation of photons in a two-dimensional electron sheet

    International Nuclear Information System (INIS)

    Nieves, Jose F.

    2010-01-01

    We apply the thermal field theory methods to study the propagation of photons in a plasma layer, that is a plasma in which the electrons are confined to a two-dimensional plane sheet. We calculate the photon self-energy and determine the appropriate expression for the photon propagator in such a medium, from which the properties of the propagating modes are obtained. The formulas for the photon dispersion relations and polarization vectors are derived explicitly in some detail for some simple cases of the thermal distributions of the charged particle gas, and appropriate formulas that are applicable in more general situations are also given.

  13. Analysis of spatial thermal field in a magnetic bearing

    Science.gov (United States)

    Wajnert, Dawid; Tomczuk, Bronisław

    2018-03-01

    This paper presents two mathematical models for temperature field analysis in a new hybrid magnetic bearing. Temperature distributions have been calculated using a three dimensional simulation and a two dimensional one. A physical model for temperature testing in the magnetic bearing has been developed. Some results obtained from computer simulations were compared with measurements.

  14. Development of the finite element method in the thermal field. TRIO-EF software for thermal and radiation analysis

    International Nuclear Information System (INIS)

    Casalotti, N.; Magnaud, J.P.

    1989-01-01

    The possibilities of the TRIO-EF software in the thermal field are presented. The TRIO-EF is a computer program based on the finite element method and used for three-dimensional incompressible flow analysis. It enables the calculation of three-dimensional heat transfer and the fluid/structure analysis. The geometrically complex radiative reactor systems are taken into account in the form factor calculation. The implemented algorithms are described [fr

  15. Test of quantum thermalization in the two-dimensional transverse-field Ising model.

    Science.gov (United States)

    Blaß, Benjamin; Rieger, Heiko

    2016-12-01

    We study the quantum relaxation of the two-dimensional transverse-field Ising model after global quenches with a real-time variational Monte Carlo method and address the question whether this non-integrable, two-dimensional system thermalizes or not. We consider both interaction quenches in the paramagnetic phase and field quenches in the ferromagnetic phase and compare the time-averaged probability distributions of non-conserved quantities like magnetization and correlation functions to the thermal distributions according to the canonical Gibbs ensemble obtained with quantum Monte Carlo simulations at temperatures defined by the excess energy in the system. We find that the occurrence of thermalization crucially depends on the quench parameters: While after the interaction quenches in the paramagnetic phase thermalization can be observed, our results for the field quenches in the ferromagnetic phase show clear deviations from the thermal system. These deviations increase with the quench strength and become especially clear comparing the shape of the thermal and the time-averaged distributions, the latter ones indicating that the system does not completely lose the memory of its initial state even for strong quenches. We discuss our results with respect to a recently formulated theorem on generalized thermalization in quantum systems.

  16. Test of quantum thermalization in the two-dimensional transverse-field Ising model

    Science.gov (United States)

    Blaß, Benjamin; Rieger, Heiko

    2016-01-01

    We study the quantum relaxation of the two-dimensional transverse-field Ising model after global quenches with a real-time variational Monte Carlo method and address the question whether this non-integrable, two-dimensional system thermalizes or not. We consider both interaction quenches in the paramagnetic phase and field quenches in the ferromagnetic phase and compare the time-averaged probability distributions of non-conserved quantities like magnetization and correlation functions to the thermal distributions according to the canonical Gibbs ensemble obtained with quantum Monte Carlo simulations at temperatures defined by the excess energy in the system. We find that the occurrence of thermalization crucially depends on the quench parameters: While after the interaction quenches in the paramagnetic phase thermalization can be observed, our results for the field quenches in the ferromagnetic phase show clear deviations from the thermal system. These deviations increase with the quench strength and become especially clear comparing the shape of the thermal and the time-averaged distributions, the latter ones indicating that the system does not completely lose the memory of its initial state even for strong quenches. We discuss our results with respect to a recently formulated theorem on generalized thermalization in quantum systems. PMID:27905523

  17. Intelligent trend analysis for a solar thermal energy collector field

    Science.gov (United States)

    Juuso, E. K.

    2018-03-01

    Solar thermal power plants collect available solar energy in a usable form at a temperature range which is adapted to the irradiation levels and seasonal variations. Solar energy can be collected only when the irradiation is high enough to produce the required temperatures. During the operation, a trade-off of the temperature and the flow is needed to achieve a good level for the collected power. The scaling approach brings temporal analysis to all measurements and features: trend indices are calculated by comparing the averages in the long and short time windows, a weighted sum of the trend index and its derivative detects the trend episodes and severity of the trend is estimated by including also the variable level in the sum. The trend index, trend episodes and especially, the deviation index reveal early evolving changes in the operating conditions, including cloudiness and load disturbances. The solution is highly compact: all variables, features and indices are transformed to the range [-2, 2] and represented in natural language which is important in integrating data-driven solutions with domain expertise. The special situations detected during the test campaigns are explained well.

  18. Magnetic field induced augmented thermal conduction phenomenon in magneto-nanocolloids

    International Nuclear Information System (INIS)

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

    2016-01-01

    Magnetic field induced augmented thermal conductivity of magneto-nanocolloids involving nanoparticles, viz. Fe_2O_3, Fe_3O_4, NiO and Co_3O_4 dispersed in different base fluids have been reported. Experiments reveal the augmented thermal transport under external applied magnetic field. A maximum thermal conductivity enhancement ∼114% is attained at 7.0 vol% concentration and 0.1 T magnetic flux density for Fe_3O_4/EG magneto-nanocolloid. However, a maximum ∼82% thermal conductivity enhancement is observed for Fe_3O_4/kerosene magneto-nanocolloid for the same concentration but relatively at low magnetic flux density (∼0.06 T). Thereby, a strong effect of fluid as well as particle physical properties on the chain formation propensity, leading to enhanced conduction, in such systems is observed. Co_3O_4 nanoparticles show insignificant effect on the thermal conductivity enhancement of MNCs due to their minimal magnetic moment. A semi-empirical approach has been proposed to understand the mechanism and physics behind the thermal conductivity enhancement under external applied magnetic field, in tune with near field magnetostatic interactions as well as Neel relaxivity of the magnetic nanoparticles. Furthermore, the model is able to predict the phenomenon of enhanced thermal conductivity as a function of physical parameters and shows good agreement with the experimental observations. - Highlights: • Heat conduction in magneto-nanocolloids augments tremendously under magnetic field. • Oxide nanoparticles of Fe, Ni and Co dispersed in variant base fluids are used. • Enhancement in heat conduction is due to the formation of thermally conductive chains. • Proposed semi-empirical model shows good agreement with the experimental results.

  19. Magnetic field induced augmented thermal conduction phenomenon in magneto-nanocolloids

    Energy Technology Data Exchange (ETDEWEB)

    Katiyar, Ajay, E-mail: ajay_cim@rediffmail.com [Research and Innovation Centre (DRDO), Indian Institute of Technology Madras Research Park, Chennai 600 113 (India); Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Dhar, Purbarun, E-mail: purbarun@iitrpr.ac.in [Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India); Nandi, Tandra, E-mail: tandra_n@rediffmail.com [Defence Materials and Stores Research and Development Establishment (DRDO), G.T. Road, Kanpur 208 013 (India); Das, Sarit K., E-mail: skdas@iitrpr.ac.in [Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600 036 (India)

    2016-12-01

    Magnetic field induced augmented thermal conductivity of magneto-nanocolloids involving nanoparticles, viz. Fe{sub 2}O{sub 3}, Fe{sub 3}O{sub 4}, NiO and Co{sub 3}O{sub 4} dispersed in different base fluids have been reported. Experiments reveal the augmented thermal transport under external applied magnetic field. A maximum thermal conductivity enhancement ∼114% is attained at 7.0 vol% concentration and 0.1 T magnetic flux density for Fe{sub 3}O{sub 4}/EG magneto-nanocolloid. However, a maximum ∼82% thermal conductivity enhancement is observed for Fe{sub 3}O{sub 4}/kerosene magneto-nanocolloid for the same concentration but relatively at low magnetic flux density (∼0.06 T). Thereby, a strong effect of fluid as well as particle physical properties on the chain formation propensity, leading to enhanced conduction, in such systems is observed. Co{sub 3}O{sub 4} nanoparticles show insignificant effect on the thermal conductivity enhancement of MNCs due to their minimal magnetic moment. A semi-empirical approach has been proposed to understand the mechanism and physics behind the thermal conductivity enhancement under external applied magnetic field, in tune with near field magnetostatic interactions as well as Neel relaxivity of the magnetic nanoparticles. Furthermore, the model is able to predict the phenomenon of enhanced thermal conductivity as a function of physical parameters and shows good agreement with the experimental observations. - Highlights: • Heat conduction in magneto-nanocolloids augments tremendously under magnetic field. • Oxide nanoparticles of Fe, Ni and Co dispersed in variant base fluids are used. • Enhancement in heat conduction is due to the formation of thermally conductive chains. • Proposed semi-empirical model shows good agreement with the experimental results.

  20. Thermal Stress FE Analysis of Large-scale Gas Holder Under Sunshine Temperature Field

    Science.gov (United States)

    Li, Jingyu; Yang, Ranxia; Wang, Hehui

    2018-03-01

    The temperature field and thermal stress of Man type gas holder is simulated by using the theory of sunshine temperature field based on ASHRAE clear-sky model and the finite element method. The distribution of surface temperature and thermal stress of gas holder under the given sunshine condition is obtained. The results show that the thermal stress caused by sunshine can be identified as one of the important factors for the failure of local cracked oil leakage which happens on the sunny side before on the shady side. Therefore, it is of great importance to consider the sunshine thermal load in the stress analysis, design and operation of large-scale steel structures such as the gas holder.

  1. Flow in porous media under the influence of thermal fields

    Energy Technology Data Exchange (ETDEWEB)

    Bories, S; Thirriot, C

    1970-01-01

    Fluid flow in porous media, including natural convection caused by temperature fields, is of particular importance in the exploitation of petroleum deposits. Laboratory experiments with a horizontal Hele-Shaw model in which the convection currents can be visually observed, are reported. The main observations are concerned with fairly stable flow regime cells and the velocity distribution. Photos of the flow, and graphs of the temperature distribution measured by interferometric methods, are given. The essential elements observed are well-represented by a simplified theory; at large Reynolds numbers, large temperature gradients have been observed in the vicinity of the isothermal boundaries. The temperature distribution can be expressed by a dimensionless law, and it seems possible to generalize the observations from the Hele-Shaw model to flow in porous media.

  2. Field survey of occupants thermal comfort in rooms with displacement ventilation

    DEFF Research Database (Denmark)

    Pitchurov, G.; Naidenov, K.; Melikov, Arsen Krikor

    2002-01-01

    Field survey of occupants´ response to the thermal environment in eight office buildings with displacement ventilation was performed. The response of 227 occupants (94 males and 133 females) was collected and analysed. A neutral thermal sensation was reported by 37% of the occupants, and between...... slightly cool and slightly warm by more than 85% of the occupants. The occupants´ thermal sensation was close to the predictions by the PMV index. About 24% of the surveyed occupants complained that they were daily bothered by draught mainly at lower leg. Presence of draught discomfort was verified even...

  3. Field Synergy Analysis and Optimization of the Thermal Behavior of Lithium Ion Battery Packs

    Directory of Open Access Journals (Sweden)

    Hongwen He

    2017-01-01

    Full Text Available In this study, a three dimensional (3D modeling has been built for a lithium ion battery pack using the field synergy principle to obtain a better thermal distribution. In the model, the thermal behavior of the battery pack was studied by reducing the maximum temperature, improving the temperature uniformity and considering the difference between the maximum and maximum temperature of the battery pack. The method is further verified by simulation results based on different environmental temperatures and discharge rates. The thermal behavior model demonstrates that the design and cooling policy of the battery pack is crucial for optimizing the air-outlet patterns of electric vehicle power cabins.

  4. Heat transfer and thermal stress analysis in fluid-structure coupled field

    International Nuclear Information System (INIS)

    Li, Ming-Jian; Pan, Jun-Hua; Ni, Ming-Jiu; Zhang, Nian-Mei

    2015-01-01

    In this work, three-dimensional simulation on conjugate heat transfer in a fluid-structure coupled field was carried out. The structure considered is from the dual-coolant lithium-lead (DCLL) blanket, which is the key technology of International Thermo-nuclear Experimental Reactor (ITER). The model was developed based on finite element-finite volume method and was employed to investigate mechanical behaviours of Flow Channel Insert (FCI) and heat transfer in the blanket under nuclear reaction. Temperature distribution, thermal deformation and thermal stresses were calculated in this work, and the effects of thermal conductivity, convection heat transfer coefficient and flow velocity were analyzed. Results show that temperature gradients and thermal stresses of FCI decrease when FCI has better heat conductivity. Higher convection heat transfer coefficient will result in lower temperature, thermal deformations and stresses in FCI. Analysis in this work could be a theoretical basis of blanket optimization. - Highlights: • We use FVM and FEM to investigate FCI structural safety considering heat transfer and FSI effects. • Higher convective heat transfer coefficient is beneficial for the FCI structural safety without much affect to bulk flow temperature. • Smaller FCI thermal conductivity can better prevent heat leakage into helium, yet will increase FCI temperature gradient and thermal stress. • Three-dimensional simulation on conjugate heat transfer in a fluid-structure coupled field was carried out

  5. Meshed doped silicon photonic crystals for manipulating near-field thermal radiation

    Science.gov (United States)

    Elzouka, Mahmoud; Ndao, Sidy

    2018-01-01

    The ability to control and manipulate heat flow is of great interest to thermal management and thermal logic and memory devices. Particularly, near-field thermal radiation presents a unique opportunity to enhance heat transfer while being able to tailor its characteristics (e.g., spectral selectivity). However, achieving nanometric gaps, necessary for near-field, has been and remains a formidable challenge. Here, we demonstrate significant enhancement of the near-field heat transfer through meshed photonic crystals with separation gaps above 0.5 μm. Using a first-principle method, we investigate the meshed photonic structures numerically via finite-difference time-domain technique (FDTD) along with the Langevin approach. Results for doped-silicon meshed structures show significant enhancement in heat transfer; 26 times over the non-meshed corrugated structures. This is especially important for thermal management and thermal rectification applications. The results also support the premise that thermal radiation at micro scale is a bulk (rather than a surface) phenomenon; the increase in heat transfer between two meshed-corrugated surfaces compared to the flat surface (8.2) wasn't proportional to the increase in the surface area due to the corrugations (9). Results were further validated through good agreements between the resonant modes predicted from the dispersion relation (calculated using a finite-element method), and transmission factors (calculated from FDTD).

  6. Role of anisotropic thermal conductivity in the reversed-field pinch dynamics

    International Nuclear Information System (INIS)

    Onofri, M.; Malara, F.; Veltri, P.

    2011-01-01

    Two compressible magnetohydrodynamics simulations of the reversed-field pinch are performed, with isotropic and anisotropic thermal conductivity. We describe in detail the numerical method we use to reproduce the effect of a large parallel thermal conductivity, which makes magnetic field lines almost isothermal. We compare the results of the two simulations, showing that the anisotropic thermal conductivity causes the formation of a hot island when closed magnetic surfaces exist, while temperature becomes almost uniform when the magnetic field is chaotic. After a transient single-helicity state that is formed in the initial phase, a stationary state is reached where the RFP configuration exists in a multiple helicity state, even though the Hartmann number is below the threshold found in previous simulations for the formation of multiple helicity states.

  7. Prediction of Equilibrium States of Kinematic and Thermal Fields in Homogeneous Turbulence Submitted To the Rotation

    International Nuclear Information System (INIS)

    Chebbi, Besma; Bouzaiane, Mounir; Lili, Taieb

    2009-01-01

    In this work, effects of rotation on the evolution of kinematic and thermal fields in homogeneous sheared turbulence are investigated using second order closure modeling. The Launder-Reece-Ro di models, the Speziale-Sarkar-Gatski model and the Shih-Lumley models are retained for pressure-strain correlation and pressure-temperature correlation. Whereas classic models are retained for time evolution equations of kinematic and thermal dissipation rates. The fourth order Runge-Kutta method is used to resolve three non linear differential systems obtained after modeling. The numerical integration is carried out separately for several values of the dimensionless rotation number R equal to 0, 0.25 and 0.5. The obtained results are compared to the recent results of Direct Numerical Simulations of G.Brethouwer. The results have confirmed the asymptotic equilibrium behaviors of kinematic and thermal dimensionless parameters. Furthermore they have shown that rotation affects not only kinematic field but also thermal field. The coupling between the Speziale-Sarkar-Gatski model and the Launder-Reece-Rodi model is of a big contribution on the prediction of kinematic and thermal fields

  8. Manipulation and simulations of thermal field profiles in laser heat-mode lithography

    Science.gov (United States)

    Wei, Tao; Wei, Jingsong; Wang, Yang; Zhang, Long

    2017-12-01

    Laser heat-mode lithography is a very useful method for high-speed fabrication of large-area micro/nanostructures. To obtain nanoscale pattern structures, one needs to manipulate the thermal diffusion channels. This work reports the manipulation of the thermal diffusion in laser heat-mode lithography and provides methods to restrain the in-plane thermal diffusion and improve the out-of-plane thermal diffusion. The thermal field profiles in heat-mode resist thin films have been given. It is found that the size of the heat-spot can be decreased by decreasing the thickness of the heat-mode resist thin films, inserting the thermal conduction layers, and shortening the laser irradiation time. The optimized laser writing strategy is also given, where the in-plane thermal diffusion is completely restrained and the out-of-plane thermal diffusion is improved. The heat-spot size is almost equal to that of the laser spot, accordingly. This work provides a very important guide to laser heat-mode lithography.

  9. Enhanced performance of thermal-assisted electron field emission based on barium oxide nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Yunkang [Department of Mathematics and Physics, Nanjing Institute of technology, Nanjing, 211167 (China); Chen, Jing, E-mail: chenjingmoon@gmail.com [School of Electronic Science & Engineering, Southeast University, Nanjing, 210096 (China); Zhang, Yuning; Zhang, Xiaobing; Lei, Wei; Di, Yunsong [School of Electronic Science & Engineering, Southeast University, Nanjing, 210096 (China); Zhang, Zichen, E-mail: zz241@ime.ac.cn [Integrated system for Laser applications Group, Institute of Microelectronics of Chinese Academy of Sciences, 100029, Beijing (China)

    2017-02-28

    Highlights: • A possible mechanism for thermal-assisted electric field was demonstrated. • A new path for the architecture of the novel nanomaterial and methodology for its potential application in the field emission device area was provided. • The turn-on field, the threshold field and the field emission current density were largely related to the temperature of the cathode. • The relationship between the work function of emitter material and the temperature of emitter was found. - Abstract: In this paper, thermal-assisted field emission properties of barium oxide (BaO) nanowire synthesized by a chemical bath deposition method were investigated. The morphology and composition of BaO nanowire were characterized by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SED), X-ray diffraction (XRD), and energy dispersive X-ray spectrometer (EDX) respectively. The turn-on field, threshold field and the emission current density could be affected relatively due to the thermal-assisted effect when the electric field was applied, in the meanwhile, the turn-on field for BaO nanowire was measured to be decreased from 1.12 V/μm to 0.66 V/μm when the temperature was raised from 293 K to 593 K, whereas for the threshold field was found to decrease from 3.64 V/μm to 2.12 V/μm. The improved performance was demonstrated due to the reduced work function of the BaO nanowire as the agitation temperature increasing, leading to the higher probability of electrons tunneling through the energy barrier and enhancement of the field emission properties of BaO emitters.

  10. Enhanced performance of thermal-assisted electron field emission based on barium oxide nanowire

    International Nuclear Information System (INIS)

    Cui, Yunkang; Chen, Jing; Zhang, Yuning; Zhang, Xiaobing; Lei, Wei; Di, Yunsong; Zhang, Zichen

    2017-01-01

    Highlights: • A possible mechanism for thermal-assisted electric field was demonstrated. • A new path for the architecture of the novel nanomaterial and methodology for its potential application in the field emission device area was provided. • The turn-on field, the threshold field and the field emission current density were largely related to the temperature of the cathode. • The relationship between the work function of emitter material and the temperature of emitter was found. - Abstract: In this paper, thermal-assisted field emission properties of barium oxide (BaO) nanowire synthesized by a chemical bath deposition method were investigated. The morphology and composition of BaO nanowire were characterized by field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SED), X-ray diffraction (XRD), and energy dispersive X-ray spectrometer (EDX) respectively. The turn-on field, threshold field and the emission current density could be affected relatively due to the thermal-assisted effect when the electric field was applied, in the meanwhile, the turn-on field for BaO nanowire was measured to be decreased from 1.12 V/μm to 0.66 V/μm when the temperature was raised from 293 K to 593 K, whereas for the threshold field was found to decrease from 3.64 V/μm to 2.12 V/μm. The improved performance was demonstrated due to the reduced work function of the BaO nanowire as the agitation temperature increasing, leading to the higher probability of electrons tunneling through the energy barrier and enhancement of the field emission properties of BaO emitters.

  11. Thermal Analysis of NR Composite with MWCNTs Aligned in a Magnetic Field

    Directory of Open Access Journals (Sweden)

    Jin Xu

    2015-01-01

    Full Text Available We got the aligned carbon tube in the rubber matrix through magnetic field. TEM shows that Fe3O4 is symmetrically coated on the outer surface of MWCNTs. Diffraction peaks corresponding to Fe3O4 cubic crystal also appeared in the X-ray diffraction spectra. Thermal conductivity of composites increases by filling the appropriate content of carbon tube. If the magnetic field is larger and the direction time is longer, a greater thermal conductivity of composites can be obtained.

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

    KAUST Repository

    El-Amin, Mohamed; Sun, Shuyu

    2011-01-01

    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.

  13. 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.

  14. Threshold and maximum power evolution of stimulated Brillouin scattering and Rayleigh backscattering in a single mode fiber segment

    International Nuclear Information System (INIS)

    Sanchez-Lara, R; Alvarez-Chavez, J A; Mendez-Martinez, F; De la Cruz-May, L; Perez-Sanchez, G G

    2015-01-01

    The behavior of stimulated Brillouin scattering (SBS) and Rayleigh backscattering phenomena, which limit the forward transmission power in modern, ultra-long haul optical communication systems such as dense wavelength division multiplexing systems is analyzed via simulation and experimental investigation of threshold and maximum power. Evolution of SBS, Rayleigh scattering and forward powers are experimentally investigated with a 25 km segment of single mode fiber. Also, a simple algorithm to predict the generation of SBS is proposed where two criteria of power thresholds was used for comparison with experimental data. (paper)

  15. Statistical properties of intensity of partially polarised semiconductor laser light backscattered by a single-mode optical fibre

    International Nuclear Information System (INIS)

    Alekseev, A E; Potapov, V T; Gorshkov, B G

    2015-01-01

    We report the results of studying statistical properties of the intensity of partially polarised coherent light backscattered by a single mode optical fibre. An expression is derived for the deviation of the backscattered light intensity depending on the scattering region length, the degree of the light source coherence and the degree of scattered light polarisation. It is shown that the backscattered light in a fibre scattered-light interferometer is partially polarised with the polarisation degree P = 1/3 in the case of external perturbations of the interferometer fibre. (scattering of light)

  16. 75 W 40% efficiency single-mode all-fiber erbium-doped laser cladding pumped at 976 nm.

    Science.gov (United States)

    Kotov, L V; Likhachev, M E; Bubnov, M M; Medvedkov, O I; Yashkov, M V; Guryanov, A N; Lhermite, J; Février, S; Cormier, E

    2013-07-01

    Optimization of Yb-free Er-doped fiber for lasers and amplifiers cladding pumped at 976 nm was performed in this Letter. The single-mode fiber design includes an increased core diameter of 34 μm and properly chosen erbium and co-dopant concentrations. We demonstrate an all-fiber high power laser and power amplifier based on this fiber with the record slope efficiency of 40%. To the best of our knowledge, the achieved output power of 75 W is the highest power reported for such lasers.

  17. Self-pulsing in a 2 km single-mode fiber with the seed source broadened via WNS phase modulation

    Science.gov (United States)

    Zha, Congwen; Sun, Yinhong; Wang, Yanshan; Li, Tenglong; Peng, Wanjing; Ma, Yi; Zhang, Kai

    2018-03-01

    The seed source with spectral linewidth broadening via phase modulation is potential to achieve the higher output power with effective SBS suppression. However, self-pulsing from the amplifier output is harmful. In this work, we study the self-pulsing characteristics in a long single-mode fiber with lower self-pulsing threshold instead of the high power amplifier. We provide a powerful experimental support for the self-pulsing mechanism in high-power narrow-linewidth fiber lasers, which is important for further output power scaling.

  18. Toward single-mode UV to near-IR guidance using hollow-core anti-resonant silica fiber

    DEFF Research Database (Denmark)

    Habib, Md Selim; Antonio-Lopez, Jose Enrique; Van Newkirk, Amy

    2017-01-01

    Hollow-core anti-resonant (HC-AR) fibers with a “negative-curvature” of the core-cladding boundary have been extensively studied over the past few years owing to their low loss and wide transmission bandwidths. The key unique feature of the HC-AR fiber is that the coupling between the core and cl...... a silica HC-AR fiber having a single ring of 7 non-touching capillaries, designed to have effectively single-mode operation and low loss from UV to near-IR....

  19. The effect of irradiation temperature on the optical attenuation recovery in heavily Ge-doped single mode silica core fibers

    International Nuclear Information System (INIS)

    Bertolotti, M.; Mabrouk, M.A.; Ferrari, A.; Serra, A.; Viezzoli, G.

    1992-01-01

    The behaviour under irradiation of a single mode fiber heavily doped with germanium has been investigated at 0.85 μm and 1.3 μm under different irradiation temperatures in the range from -65degC to 60degC. The time behaviour of the recovery of the induced attenuation has been described using empirical equations, for different temperatures. An nth order kinetics seems appropriate to describe the results and the order of kinetics has been determined at different temperatures. (orig.)

  20. The spiral field inhibition of thermal conduction in two-fluid solar wind models

    Science.gov (United States)

    Nerney, S.; Barnes, A.

    1978-01-01

    The paper reports on two-field models which include the inhibition of thermal conduction by the spiraling interplanetary field to determine whether any of the major conclusions obtained by Nerney and Barnes (1977) needs to be modified. Comparisons with straight field line models reveal that for most base conditions, the primary effect of the inhibition of thermal conduction is the bottling-up of heat in the electrons as well as the quite different temperature profiles at a large heliocentric radius. The spiral field solutions show that coronal hole boundary conditions do not correspond to states of high-speed streams as observed at 1 AU. The two-fluid models suggest that the spiral field inhibition of thermal conduction in the equatorial plane will generate higher gas pressures in comparison with flows along the solar rotation axis (between 1 and 10 AU). In particular, massive outflows of stellar winds, such as outflow from T Tauri stars, cannot be driven by thermal conduction. The conclusions of Nerney and Barnes remain essentially unchanged.

  1. Thermal Field Analysis and Simulation of an Infrared Belt Furnace Used for Solar Cells

    Directory of Open Access Journals (Sweden)

    Bai Lu

    2014-01-01

    Full Text Available During solar cell firing, volatile organic compounds (VOC and a small number of metal particles were removed using the gas flow. When the gas flow was disturbed by the thermal field of infrared belt furnace and structure, the metal particles in the discharging gas flow randomly adhered to the surface of solar cell, possibly causing contamination. Meanwhile, the gas flow also affected the thermal uniformity of the solar cell. In this paper, the heating mechanism of the solar cell caused by radiation, convection, and conduction during firing was analyzed. Afterward, four 2-dimensional (2D models of the furnace were proposed. The transient thermal fields with different gas inlets, outlets, and internal structures were simulated. The thermal fields and the temperature of the solar cell could remain stable and uniform when the gas outlets were installed at the ends and in the middle of the furnace, with the gas inlets being distributed evenly. To verify the results, we produced four types of furnaces according to the four simulated results. The experimental results indicated that the thermal distribution of the furnace and the characteristics of the solar cells were consistent with the simulation. These experiments improved the efficiency of the solar cells while optimizing the solar cell manufacturing equipment.

  2. Thermal management in MoS{sub 2} based integrated device using near-field radiation

    Energy Technology Data Exchange (ETDEWEB)

    Peng, Jiebin [Department of Physics, National University of Singapore, Singapore 117546 (Singapore); Zhang, Gang, E-mail: zhangg@ihpc.a-star.edu.sg [Institute of High Performance Computing, A*STAR, Singapore 138632 (Singapore); Li, Baowen [Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309 (United States)

    2015-09-28

    Recently, wafer-scale growth of monolayer MoS{sub 2} films with spatial homogeneity is realized on SiO{sub 2} substrate. Together with the latest reported high mobility, MoS{sub 2} based integrated electronic devices are expected to be fabricated in the near future. Owing to the low lattice thermal conductivity in monolayer MoS{sub 2}, and the increased transistor density accompanied with the increased power density, heat dissipation will become a crucial issue for these integrated devices. In this letter, using the formalism of fluctuation electrodynamics, we explored the near-field radiative heat transfer from a monolayer MoS{sub 2} to graphene. We demonstrate that in resonance, the maximum heat transfer via near-field radiation between MoS{sub 2} and graphene can be ten times higher than the in-plane lattice thermal conduction for MoS{sub 2} sheet. Therefore, an efficient thermal management strategy for MoS{sub 2} integrated device is proposed: Graphene sheet is brought into close proximity, 10–20 nm from MoS{sub 2} device; heat energy transfer from MoS{sub 2} to graphene via near-field radiation; this amount of heat energy then be conducted to contact due to ultra-high lattice thermal conductivity of graphene. Our work sheds light for developing cooling strategy for nano devices constructing with low thermal conductivity materials.

  3. Field studies of submerged-diffuser thermal plumes with comparisons to predictive model results

    International Nuclear Information System (INIS)

    Frigo, A.A.; Paddock, R.A.; Ditmars, J.D.

    1976-01-01

    Thermal plumes from submerged discharges of cooling water from two power plants on Lake Michigan were studied. The system for the acquisition of water temperatures and ambient conditions permitted the three-dimensional structure of the plumes to be determined. The Zion Nuclear Power Station has two submerged discharge structures separated by only 94 m. Under conditions of flow from both structures, interaction between the two plumes resulted in larger thermal fields than would be predicted by the superposition of single non-interacting plumes. Maximum temperatures in the near-field region of the plume compared favorably with mathematical model predictions. A comparison of physical-model predictions for the plume at the D. C. Cook Nuclear Plant with prototype measurements indicated good agreement in the near-field region, but differences in the far-field occurred as similitude was not preserved there

  4. Thermal electron acceleration by electric field spikes in the outer radiation belt: generation of field-aligned pitch angle distributions

    Science.gov (United States)

    Vasko, I.; Agapitov, O. V.; Mozer, F.; Artemyev, A.

    2015-12-01

    Van Allen Probes observations in the outer radiation belt have demonstrated an abundance non-linear electrostatic stucture called Time Domain Structures (TDS). One of the type of TDS is electrostatic electron-acoustic double layers (DL). Observed DLs are frequently accompanied by field-aligned (bi-directional) pitch angle distributions (PAD) of electrons with energies from hundred eVs up to several keV (rarely up to tens of keV). We perform numerical simulations of the DL interaction with thermal electrons making use of the test particle approach. DL parameters assumed in the simulations are adopted from observations. We show that DLs accelerate thermal electrons parallel to the magnetic field via the electrostatic Fermi mechanism, i.e. due to reflections from DL potential humps. Due to this interaction some fraction of electrons is scattered into the loss cone. The electron energy gain is larger for larger DL scalar potential amplitudes and higher propagation velocities. In addition to the Fermi mechanism electrons can be trapped by DLs in their generation region and accelerated due to transport to higher latitudes. Both mechanisms result in formation of field-aligned PADs for electrons with energies comparable to those found in observations. The Fermi mechanism provides field-aligned PADs for <1 keV electrons, while the trapping mechanism extends field-aligned PADs to higher energy electrons.

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

    Directory of Open Access Journals (Sweden)

    T. J. Barton

    2012-12-01

    Full Text Available 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 (2007PHPAEN1070-664X10.1063/1.2779281; J. Zhou, K. R. Samokhvalova, and C. Chen, Phys. Plasmas 15, 023102 (2008PHPAEN1070-664X10.1063/1.2837891]. 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, the conservations of the rms thermal emittances, the adiabatic equation of state, and the Debye length are verified in the simulations. Furthermore, the adiabatic thermal beam is found be stable in the parameter regime where the simulations are performed.

  6. Thermal conduction in polymeric nanofluids under mean field approximation: role of interfacial adsorption layers

    International Nuclear Information System (INIS)

    Nisha, M R; Philip, J

    2013-01-01

    Polymeric nanofluids of TiO 2 /PVA (polyvinyl alcohol) and Cu/PVA have been prepared by dispersing nanoparticles of TiO 2 or metallic copper in PVA. The thermal diffusivities and thermal conductivities of these nanofluids have been measured as a function of particle loading following a thermal wave interference technique in a thermal wave resonant cavity. It is found that in both cases thermal conductivity increases with particle concentration, with Cu/PVA nanofluids showing a much larger increase. The results have been compared with the corresponding values calculated following different theoretical models. Comparison of the results with model-based calculations shows that the thermal conductivity variations in these nanofluids are within the framework of the classical mean field theory including the formation of thin interfacial adsorption layers around nanoparticles. Although the molecular weight of PVA is very high, it is found that the adsorption layer thickness is limited by the hydrodynamic radius of the nanoparticles. It is found that particle clustering followed by interfacial layering accounts for the larger increase in thermal conductivity found for Cu/PVA compared to TiO 2 /PVA. (paper)

  7. Low-NA single-mode LMA photonic crystal fiber amplifier

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Laurila, Marko; Scolari, Lara

    2011-01-01

    a spatially Distributed Mode Filter (DMF). This approach achieves SM performance in a short and straight rod fiber and allows preform tolerances to be compensated during draw. A low-NA SM rod fiber amplifier having a mode field diameter of ~60μm at 1064nm and a pump absorption of 27dB/m at 976nm...

  8. Observing Exoplanets with High-dispersion Coronagraphy. II. Demonstration of an Active Single-mode Fiber Injection Unit

    Energy Technology Data Exchange (ETDEWEB)

    Mawet, D.; Ruane, G.; Xuan, W.; Echeverri, D.; Klimovich, N.; Randolph, M.; Fucik, J.; Wang, J.; Dekany, R.; Delorme, J.-R. [Department of Astronomy, California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States); Wallace, J. K.; Vasisht, G.; Mennesson, B.; Choquet, E.; Serabyn, E., E-mail: dmawet@astro.caltech.edu [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

    2017-04-01

    High-dispersion coronagraphy (HDC) optimally combines high-contrast imaging techniques such as adaptive optics/wavefront control plus coronagraphy to high spectral resolution spectroscopy. HDC is a critical pathway toward fully characterizing exoplanet atmospheres across a broad range of masses from giant gaseous planets down to Earth-like planets. In addition to determining the molecular composition of exoplanet atmospheres, HDC also enables Doppler mapping of atmosphere inhomogeneities (temperature, clouds, wind), as well as precise measurements of exoplanet rotational velocities. Here, we demonstrate an innovative concept for injecting the directly imaged planet light into a single-mode fiber, linking a high-contrast adaptively corrected coronagraph to a high-resolution spectrograph (diffraction-limited or not). Our laboratory demonstration includes three key milestones: close-to-theoretical injection efficiency, accurate pointing and tracking, and on-fiber coherent modulation and speckle nulling of spurious starlight signal coupling into the fiber. Using the extreme modal selectivity of single-mode fibers, we also demonstrated speckle suppression gains that outperform conventional image-based speckle nulling by at least two orders of magnitude.

  9. The quantum dynamics of two qubits inside two distant microcavities connected via a single-mode optical fiber

    International Nuclear Information System (INIS)

    Nguyen, Van Hieu; Nguyen, Bich Ha; Duong, Hai Trieu

    2010-01-01

    For application to studying the transmission of quantum information, also called quantum communication, between two identical qubits placed inside two identical single-mode microcavities connected via a single-mode optical fiber, the time evolution of this system is investigated. In the Markovian approximation, the von Neumann equation for its reduced density matrix contains a completely positive linear operator called the Liouvillian operator describing the decoherence of this system due to its interaction with the environment. By using the Linblad formula for the Liouvillian operator, a system of rate equations can be derived. In the special case of resonance between the energy difference of two states in each qubit and the energy of the fiber mode, the rate equations for the system excited up to the first level are solved in first order approximation with respect to the decoherence constants. It is shown that when there is no decoherence, the perfect quantum state transmission between two qubits can take place if the physical parameters of the system satisfy definite conditions. A possible extension to studying the system excited to high energy states is also discussed

  10. Multistabilities and symmetry-broken one-color and two-color states in closely coupled single-mode lasers.

    Science.gov (United States)

    Clerkin, Eoin; O'Brien, Stephen; Amann, Andreas

    2014-03-01

    We theoretically investigate the dynamics of two mutually coupled, identical single-mode semi-conductor lasers. For small separation and large coupling between the lasers, symmetry-broken one-color states are shown to be stable. In this case the light outputs of the lasers have significantly different intensities while at the same time the lasers are locked to a single common frequency. For intermediate coupling we observe stable symmetry-broken two-color states, where both lasers lase simultaneously at two optical frequencies which are separated by up to 150 GHz. Using a five-dimensional model, we identify the bifurcation structure which is responsible for the appearance of symmetric and symmetry-broken one-color and two-color states. Several of these states give rise to multistabilities and therefore allow for the design of all-optical memory elements on the basis of two coupled single-mode lasers. The switching performance of selected designs of optical memory elements is studied numerically.

  11. A sensitivity-enhanced refractive index sensor using a single-mode thin-core fiber incorporating an abrupt taper.

    Science.gov (United States)

    Shi, Jie; Xiao, Shilin; Yi, Lilin; Bi, Meihua

    2012-01-01

    A sensitivity-enhanced fiber-optic refractive index (RI) sensor based on a tapered single-mode thin-core diameter fiber is proposed and experimentally demonstrated. The sensor head is formed by splicing a section of tapered thin-core diameter fiber (TCF) between two sections of single-mode fibers (SMFs). The cladding modes are excited at the first SMF-TCF interface, and then interfere with the core mode at the second interface, thus forming an inter-modal interferometer (IMI). An abrupt taper (tens of micrometers long) made by the electric-arc-heating method is utilized, and plays an important role in improving sensing sensitivity. The whole manufacture process only involves fiber splicing and tapering, and all the fabrication process can be achieved by a commercial fiber fusion splicer. Using glycerol and water mixture solution as an example, the experimental results show that the refractive index sensitivity is measured to be 0.591 nm for 1% change of surrounding RI. The proposed sensor structure features simple structure, low cost, easy fabrication, and high sensitivity.

  12. A Sensitivity-Enhanced Refractive Index Sensor Using a Single-Mode Thin-Core Fiber Incorporating an Abrupt Taper

    Directory of Open Access Journals (Sweden)

    Jie Shi

    2012-04-01

    Full Text Available A sensitivity-enhanced fiber-optic refractive index (RI sensor based on a tapered single-mode thin-core diameter fiber is proposed and experimentally demonstrated. The sensor head is formed by splicing a section of tapered thin-core diameter fiber (TCF between two sections of single-mode fibers (SMFs. The cladding modes are excited at the first SMF-TCF interface, and then interfere with the core mode at the second interface, thus forming an inter-modal interferometer (IMI. An abrupt taper (tens of micrometers long made by the electric-arc-heating method is utilized, and plays an important role in improving sensing sensitivity. The whole manufacture process only involves fiber splicing and tapering, and all the fabrication process can be achieved by a commercial fiber fusion splicer. Using glycerol and water mixture solution as an example, the experimental results show that the refractive index sensitivity is measured to be 0.591 nm for 1% change of surrounding RI. The proposed sensor structure features simple structure, low cost, easy fabrication, and high sensitivity.

  13. Electromagnetic and Thermal Aspects of Radiofrequency Field Propagation in Ultra-High Field MRI

    NARCIS (Netherlands)

    van Lier, A.L.H.M.W.

    2012-01-01

    In MRI, a radiofrequency (RF) pulse is used to generate a signal from the spins that are polarized by a strong magnetic field. For higher magnetic field strengths, a higher frequency of the RF pulse is required in order to match the Larmor frequency. A higher frequency, in turn, leads to a shorter

  14. Transformation Laplacian metamaterials: recent advances in manipulating thermal and dc fields

    International Nuclear Information System (INIS)

    Han, Tiancheng; Qiu, Cheng-Wei

    2016-01-01

    The full control of single or even multiple physical fields has attracted intensive research attention in the past decade, thanks to the development of metamaterials and transformation optics. Significant progress has been made in vector fields (e.g., optics, electromagnetics, and acoustics), leading to a host of strikingly functional metamaterials, such as invisibility cloaks, illusion devices, concentrators, and rotators. However, metamaterials in vector fields, designed through coordinate transformation of Maxwell’s equations, usually require extreme parameters and impose challenges on the actual realization. In this context, metamaterials in scalar fields (e.g., thermal and dc fields), which are mostly governed by the Laplace equation, lead to more plausible and facile implementations, since there are native insulators and excellent conductors (serving as two extreme cases). This paper therefore is particularly dedicated to reviewing the most recent advances in Laplacian metamaterials in manipulating thermal (both transient and steady states) and dc fields, separately and (or) simultaneously. We focus on the theory, design, and realization of thermal/dc functional metamaterials that can be used to control heat flux and electric current at will. We also provide an outlook toward the challenges and future directions in this fascinating area. (review)

  15. Transformation Laplacian metamaterials: recent advances in manipulating thermal and dc fields

    Science.gov (United States)

    Han, Tiancheng; Qiu, Cheng-Wei

    2016-04-01

    The full control of single or even multiple physical fields has attracted intensive research attention in the past decade, thanks to the development of metamaterials and transformation optics. Significant progress has been made in vector fields (e.g., optics, electromagnetics, and acoustics), leading to a host of strikingly functional metamaterials, such as invisibility cloaks, illusion devices, concentrators, and rotators. However, metamaterials in vector fields, designed through coordinate transformation of Maxwell’s equations, usually require extreme parameters and impose challenges on the actual realization. In this context, metamaterials in scalar fields (e.g., thermal and dc fields), which are mostly governed by the Laplace equation, lead to more plausible and facile implementations, since there are native insulators and excellent conductors (serving as two extreme cases). This paper therefore is particularly dedicated to reviewing the most recent advances in Laplacian metamaterials in manipulating thermal (both transient and steady states) and dc fields, separately and (or) simultaneously. We focus on the theory, design, and realization of thermal/dc functional metamaterials that can be used to control heat flux and electric current at will. We also provide an outlook toward the challenges and future directions in this fascinating area.

  16. Characterization of Diamond Nanoparticles by High-Speed Micro-Thermal Field-Flow Fractionation

    Czech Academy of Sciences Publication Activity Database

    Janča, Josef

    2015-01-01

    Roč. 20, č. 8 (2015), s. 671-680 ISSN 1023-666X R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : diamond nanoparticles * high-speed microfluidic separation * micro-thermal field-flow fractionation, * article size distribution Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.515, year: 2015

  17. External electric field driving the ultra-low thermal conductivity of silicene.

    Science.gov (United States)

    Qin, Guangzhao; Qin, Zhenzhen; Yue, Sheng-Ying; Yan, Qing-Bo; Hu, Ming

    2017-06-01

    The manipulation of thermal transport is in increasing demand as heat transfer plays a critical role in a wide range of practical applications, such as efficient heat dissipation in nanoelectronics and heat conduction hindering in solid-state thermoelectrics. It is well established that the thermal transport in semiconductors and insulators (phonons) can be effectively modulated by structure engineering or materials processing. However, almost all the existing approaches involve altering the original atomic structure of materials, which would be hindered due to either irreversible structure change or limited tunability of thermal conductivity. Motivated by the inherent relationship between phonon behavior and interatomic electrostatic interaction, we comprehensively investigate the effect of external electric field, a widely used gating technique in modern electronics, on the lattice thermal conductivity (κ). Taking two-dimensional silicon (silicene) as a model, we demonstrate that by applying an electric field (E z = 0.5 V Å -1 ) the κ of silicene can be reduced to a record low value of 0.091 W m -1 K -1 , which is more than two orders of magnitude lower than that without an electric field (19.21 W m -1 K -1 ) and is even comparable to that of the best thermal insulation materials. Fundamental insights are gained from observing the electronic structures. With an electric field applied, due to the screened potential resulting from the redistributed charge density, the interactions between silicon atoms are renormalized, leading to phonon renormalization and the modulation of phonon anharmonicity through electron-phonon coupling. Our study paves the way for robustly tuning phonon transport in materials without altering the atomic structure, and would have significant impact on emerging applications, such as thermal management, nanoelectronics and thermoelectrics.

  18. Statistical properties of single-mode emission in free-electron lasers

    International Nuclear Information System (INIS)

    Bertolotti, M.; Luks, A.; Perina, J.; Perinova, V.; Sibilia, C.

    1984-01-01

    The authors of this paper discuss the statistical properties of radiation produced in the free electron laser, in the case of singlemode emission when the system is used as an amplifier, with very small gain. The coherent states technique and the q-c number correspondence is employed, starting from the master-equation and obtaining the generalized Fokker-Planck equation for the anti-normal quasidistribution function. Solutions of Fokker-Planck equation provide the photocounting distribution and its factorial moments. No losses are included. It is shown that, in the short-time approximation, the radiation field exhibits antibunching, and that the photocounting distributions, when some suitable conditions on the field intensities are fulfilled, in the stationary regime shows a two-peak behavior, evidencing the existence of bistable states

  19. Single-mode ytterbium-doped large-mode-area photonic bandgap rod fiber amplifier

    DEFF Research Database (Denmark)

    Alkeskjold, Thomas Tanggaard; Scolari, Lara; Broeng, Jes

    2011-01-01

    bandgap structure. The structure allows resonant coupling of higher-order modes from the core and acts as a spatially Distributed Mode Filter (DMF). With this approach, we demonstrate passive SM performance in an only ~50cm long and straight ytterbium-doped rod fiber. The amplifier has a mode field...... diameter of ∼59Lim at 1064nm and exhibits a pump absorption of 27dB/m at 976nm. © 2011 Optical Society of America....

  20. Experimental design rules for implementing biconically tapered single mode optical fibre displacement sensors

    Science.gov (United States)

    Arregui, Francisco J.; Matias, Ignacio R.; Bariain, Candido; Lopez-Amo, Manuel

    1998-06-01

    Tapered optical fibers are used to design couplers, wavelength division multiplexers, near field scanning optical microscopy, just to mention a few. Moreover, and due to its strong transmission dependence to external medium the tapered fiber may also be used to sense distinct parameters such as temperature, humidity, PH, etc. In this work bending effects in tapers are exploited to achieved displacement sensors and to present design rules for implementing these sensors according to the desired both range and sensitivity.

  1. Impact of shade on outdoor thermal comfort—a seasonal field study in Tempe, Arizona

    Science.gov (United States)

    Middel, Ariane; Selover, Nancy; Hagen, Björn; Chhetri, Nalini

    2016-12-01

    Shade plays an important role in designing pedestrian-friendly outdoor spaces in hot desert cities. This study investigates the impact of photovoltaic canopy shade and tree shade on thermal comfort through meteorological observations and field surveys at a pedestrian mall on Arizona State University's Tempe campus. During the course of 1 year, on selected clear calm days representative of each season, we conducted hourly meteorological transects from 7:00 a.m. to 6:00 p.m. and surveyed 1284 people about their thermal perception, comfort, and preferences. Shade lowered thermal sensation votes by approximately 1 point on a semantic differential 9-point scale, increasing thermal comfort in all seasons except winter. Shade type (tree or solar canopy) did not significantly impact perceived comfort, suggesting that artificial and natural shades are equally efficient in hot dry climates. Globe temperature explained 51 % of the variance in thermal sensation votes and was the only statistically significant meteorological predictor. Important non-meteorological factors included adaptation, thermal comfort vote, thermal preference, gender, season, and time of day. A regression of subjective thermal sensation on physiological equivalent temperature yielded a neutral temperature of 28.6 °C. The acceptable comfort range was 19.1 °C-38.1 °C with a preferred temperature of 20.8 °C. Respondents exposed to above neutral temperature felt more comfortable if they had been in air-conditioning 5 min prior to the survey, indicating a lagged response to outdoor conditions. Our study highlights the importance of active solar access management in hot urban areas to reduce thermal stress.

  2. Impact of shade on outdoor thermal comfort-a seasonal field study in Tempe, Arizona.

    Science.gov (United States)

    Middel, Ariane; Selover, Nancy; Hagen, Björn; Chhetri, Nalini

    2016-12-01

    Shade plays an important role in designing pedestrian-friendly outdoor spaces in hot desert cities. This study investigates the impact of photovoltaic canopy shade and tree shade on thermal comfort through meteorological observations and field surveys at a pedestrian mall on Arizona State University's Tempe campus. During the course of 1 year, on selected clear calm days representative of each season, we conducted hourly meteorological transects from 7:00 a.m. to 6:00 p.m. and surveyed 1284 people about their thermal perception, comfort, and preferences. Shade lowered thermal sensation votes by approximately 1 point on a semantic differential 9-point scale, increasing thermal comfort in all seasons except winter. Shade type (tree or solar canopy) did not significantly impact perceived comfort, suggesting that artificial and natural shades are equally efficient in hot dry climates. Globe temperature explained 51 % of the variance in thermal sensation votes and was the only statistically significant meteorological predictor. Important non-meteorological factors included adaptation, thermal comfort vote, thermal preference, gender, season, and time of day. A regression of subjective thermal sensation on physiological equivalent temperature yielded a neutral temperature of 28.6 °C. The acceptable comfort range was 19.1 °C-38.1 °C with a preferred temperature of 20.8 °C. Respondents exposed to above neutral temperature felt more comfortable if they had been in air-conditioning 5 min prior to the survey, indicating a lagged response to outdoor conditions. Our study highlights the importance of active solar access management in hot urban areas to reduce thermal stress.

  3. A single-mode data acquisition architecture for PET/MRI

    Energy Technology Data Exchange (ETDEWEB)

    Sportelli, Giancarlo; Belcari, Nicola; Bisogni, Maria Giuseppina; Camarlinghi, Niccolo; Zaccaro, Emanuele; Del Guerra, Alberto [Department of Physics, University of Pisa and INFN, Pisa (Italy)

    2015-05-18

    The development of MRI compatible detectors based on compact solid state photomultipliers has recently led to simultaneous fully integrated PET/MRI systems for human imaging. The PET acquisition design for MRI integration is known to have several additional constraints, including smaller space, electromagnetic compatibility issues and thermal management. The current work presents the PET acquisition architecture that has been developed for the TRIMAGE project, whose aim is to provide a cost effective, commercial grade trimodality PET/MRI/EEG scanner. The TRIMAGE PET component consists of 216 modules of 2.5 cm x 2.5 cm, arranged in 18 rectangular detectors of 5 cm x 15 cm, the latter in the axial direction, to form a full ring of 31 cm diameter. Each module consists of a staggered dual layer LYSO matrix read out by two arrays of 4 x 8 SiPMs and an ASIC. The detector board hosts a low-power low-end FPGA that performs pixel identification, energy calibration and handles the communication between the ASICs and the motherboard, which is located in proximity of the scanner. Data is streamed using high-density shielded cables and high-speed LVDS transmission to 9 low-end SoC FPGAs and from there to a central mainboard where coincidences and events statistics are processed. Coincidence data is finally transmitted to a host PC for image reconstruction. The proposed architecture and technological solutions will be presented and discussed.

  4. Optically pumped semiconductor lasers: Conception and characterization of a single mode source for Cesium atoms manipulation

    International Nuclear Information System (INIS)

    Cocquelin, B.

    2009-02-01

    Lasers currently used in atomic clocks or inertial sensors are suffering from a lack of power, narrow linewidth or compactness for future spatial missions. Optically pumped semiconductor lasers, which combine the approach of classical solid state lasers and the engineering of semiconductor laser, are considered here as a candidate to a metrological laser source dedicated to the manipulation of Cesium atoms in these instruments. These lasers have demonstrated high power laser emission in a circular single transverse mode, as well as single longitudinal mode emission, favoured by the semiconductor structure and the external cavity design. We study the definition and the characterization of a proper semiconductor structure for the cooling and the detection of Cesium atoms at 852 nm. A compact and robust prototype tunable on the Cesium D2 hyperfine structure is built. The laser frequency is locked to an atomic transition thanks to a saturated absorption setup. The emission spectral properties are investigated, with a particular attention to the laser frequency noise and the laser linewidth. Finally, we describe and model the thermal properties of the semiconductor structure, which enables the simulation of the laser power characteristic. The experimental parameters are optimised to obtain the maximum output power with our structure. Thanks to our analysis, we propose several ways to overcome these limitations, by reducing the structure heating. (authors)

  5. A single-mode data acquisition architecture for PET/MRI

    International Nuclear Information System (INIS)

    Sportelli, Giancarlo; Belcari, Nicola; Bisogni, Maria Giuseppina; Camarlinghi, Niccolo; Zaccaro, Emanuele; Del Guerra, Alberto

    2015-01-01

    The development of MRI compatible detectors based on compact solid state photomultipliers has recently led to simultaneous fully integrated PET/MRI systems for human imaging. The PET acquisition design for MRI integration is known to have several additional constraints, including smaller space, electromagnetic compatibility issues and thermal management. The current work presents the PET acquisition architecture that has been developed for the TRIMAGE project, whose aim is to provide a cost effective, commercial grade trimodality PET/MRI/EEG scanner. The TRIMAGE PET component consists of 216 modules of 2.5 cm x 2.5 cm, arranged in 18 rectangular detectors of 5 cm x 15 cm, the latter in the axial direction, to form a full ring of 31 cm diameter. Each module consists of a staggered dual layer LYSO matrix read out by two arrays of 4 x 8 SiPMs and an ASIC. The detector board hosts a low-power low-end FPGA that performs pixel identification, energy calibration and handles the communication between the ASICs and the motherboard, which is located in proximity of the scanner. Data is streamed using high-density shielded cables and high-speed LVDS transmission to 9 low-end SoC FPGAs and from there to a central mainboard where coincidences and events statistics are processed. Coincidence data is finally transmitted to a host PC for image reconstruction. The proposed architecture and technological solutions will be presented and discussed.

  6. Response of six neutron survey meters in mixed fields of fast and thermal neutrons.

    Science.gov (United States)

    Kim, S I; Kim, B H; Chang, I; Lee, J I; Kim, J L; Pradhan, A S

    2013-10-01

    Calibration neutron fields have been developed at KAERI (Korea Atomic Energy Research Institute) to study the responses of commonly used neutron survey meters in the presence of fast neutrons of energy around 10 MeV. The neutron fields were produced by using neutrons from the (241)Am-Be sources held in a graphite pile and a DT neutron generator. The spectral details and the ambient dose equivalent rates of the calibration fields were established, and the responses of six neutron survey meters were evaluated. Four single-moderator-based survey meters exhibited an under-responses ranging from ∼9 to 55 %. DINEUTRUN, commonly used in fields around nuclear reactors, exhibited an over-response by a factor of three in the thermal neutron field and an under-response of ∼85 % in the mixed fields. REM-500 (tissue-equivalent proportional counter) exhibited a response close to 1.0 in the fast neutron fields and an under-response of ∼50 % in the thermal neutron field.

  7. Effect of magnetic field on the growth of Be films prepared by thermal evaporation

    International Nuclear Information System (INIS)

    Li, Kai; Luo, Bing-chi; Tan, Xiu-lan; Zhang, Ji-qiang; Wu, Wei-dong; Liu, Ying

    2014-01-01

    Highlights: • The Be films were prepared on Si (1 0 0) substrates with and without a magnetic field by thermal evaporation, respectively. • The grain diameter in the Be film transited from 300 nm to 18 nm by application of the magnetic field. • The surface roughness of the Be film decreased from 61 nm to 3 nm by application of the magnetic field. • The Be film grown with the magnetic field was easily oxidized due to its refined grains and the oxidation was gradually decreased with increasing the etching depth in the film. - Abstract: Grain refinement of beryllium deposits is studied as a significant subject for beryllium capsule in the Inertial Confinement Fusion project. The Be films were prepared on the Si (1 0 0) substrates by thermal evaporation with and without a magnetic field, respectively. The two separate groups of prepared Be films were characterized. The results showed the grain diameter in the Be film transited from 300 nm to 18 nm and the surface roughness of the Be film decreased from 61 nm to 3 nm by application of the magnetic field during the deposition process of Be coating. However, the Be film grown with the magnetic field was easily oxidized in comparison with that grown without magnetic field due to the refined grains, and the oxidation was gradually decreased with the increase of etching depth in the Be film. The reason for grain refinement of Be film was also qualitatively described

  8. An ab-initio coupled mode theory for near field radiative thermal transfer.

    Science.gov (United States)

    Chalabi, Hamidreza; Hasman, Erez; Brongersma, Mark L

    2014-12-01

    We investigate the thermal transfer between finite-thickness planar slabs which support surface phonon polariton modes (SPhPs). The thickness-dependent dispersion of SPhPs in such layered materials provides a unique opportunity to manipulate and enhance the near field thermal transfer. The key accomplishment of this paper is the development of an ab-initio coupled mode theory that accurately describes all of its thermal transfer properties. We illustrate how the coupled mode parameters can be obtained in a direct fashion from the dispersion relation of the relevant modes of the system. This is illustrated for the specific case of a semi-infinite SiC substrate placed in close proximity to a thin slab of SiC. This is a system that exhibits rich physics in terms of its thermal transfer properties, despite the seemingly simple geometry. This includes a universal scaling behavior of the thermal conductance with the slab thickness and spacing. The work highlights and further increases the value of coupled mode theories in rapidly calculating and intuitively understanding near-field transfer.

  9. Thermal radiative near field transport between vanadium dioxide and silicon oxide across the metal insulator transition

    Energy Technology Data Exchange (ETDEWEB)

    Menges, F.; Spieser, M.; Riel, H.; Gotsmann, B., E-mail: bgo@zurich.ibm.com [IBM Research-Zurich, Säumerstrasse 4, CH-8803 Rüschlikon (Switzerland); Dittberner, M. [IBM Research-Zurich, Säumerstrasse 4, CH-8803 Rüschlikon (Switzerland); Photonics Laboratory, ETH Zurich, 8093 Zurich (Switzerland); Novotny, L. [Photonics Laboratory, ETH Zurich, 8093 Zurich (Switzerland); Passarello, D.; Parkin, S. S. P. [IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (United States)

    2016-04-25

    The thermal radiative near field transport between vanadium dioxide and silicon oxide at submicron distances is expected to exhibit a strong dependence on the state of vanadium dioxide which undergoes a metal-insulator transition near room temperature. We report the measurement of near field thermal transport between a heated silicon oxide micro-sphere and a vanadium dioxide thin film on a titanium oxide (rutile) substrate. The temperatures of the 15 nm vanadium dioxide thin film varied to be below and above the metal-insulator-transition, and the sphere temperatures were varied in a range between 100 and 200 °C. The measurements were performed using a vacuum-based scanning thermal microscope with a cantilevered resistive thermal sensor. We observe a thermal conductivity per unit area between the sphere and the film with a distance dependence following a power law trend and a conductance contrast larger than 2 for the two different phase states of the film.

  10. Wetting and motion behaviors of water droplet on graphene under thermal-electric coupling field

    Science.gov (United States)

    Zhang, Zhong-Qiang; Dong, Xin; Ye, Hong-Fei; Cheng, Guang-Gui; Ding, Jian-Ning; Ling, Zhi-Yong

    2015-02-01

    Wetting dynamics and motion behaviors of a water droplet on graphene are characterized under the electric-thermal coupling field using classical molecular dynamics simulation method. The water droplet on graphene can be driven by the temperature gradient, while the moving direction is dependent on the electric field intensity. Concretely, the water droplet on graphene moves from the low temperature region to the high temperature region for the relatively weak electric field intensity. The motion acceleration increases with the electric field intensity on graphene, whereas the moving direction switches when the electric field intensity increases up to a threshold. The essence is the change from hydrophilic to hydrophobic for the water droplet on graphene at a threshold of the electric field intensity. Moreover, the driven force of the water droplet caused by the overall oscillation of graphene has important influence on the motion behaviors. The results are helpful to control the wettability of graphene and further develop the graphene-based fluidic nanodevices.

  11. Fate of oscillating scalar fields in a thermal bath and their cosmological implications

    Science.gov (United States)

    Yokoyama, Jun'ichi

    2004-11-01

    Relaxation process of a coherent scalar field oscillation in the thermal bath is investigated using nonequilibrium quantum field theory. The Langevin-type equation of motion is obtained which has a memory term and both additive and multiplicative noise terms. The dissipation rate of the oscillating scalar field is calculated for various interactions such as Yukawa coupling, three-body scalar interaction, and biquadratic interaction. When the background temperature is larger than the oscillation frequency, the dissipation rate arising from the interactions with fermions is suppressed due to the Pauli-blocking, while it is enhanced for interactions with bosons due to the induced effect. In both cases, we find that the microphysical detailed-balance relation drives the oscillating field to a thermal equilibrium state. That is, for low-momentum modes, the classical fluctuation-dissipation theorem holds and they relax to a state the equipartition law is satisfied, while higher-momentum modes reach the state the number density of each quanta consists of the thermal boson distribution function and zero-point vacuum contribution. The temperature-dependent dissipation rates obtained here are applied to the late reheating phase of inflationary universe. It is found that in some cases the reheat temperature may take a somewhat different value from the conventional estimates, and in an extreme case the inflaton can dissipate its energy without linear interactions that leads to its decay. Furthermore the evaporation rate of the Affleck-Dine field at the onset of its oscillation is calculated.

  12. A thermal model for czochralski silicon crystal growth with an axial magnetic field

    Science.gov (United States)

    Hjellming, L. N.

    1990-07-01

    This paper presents a thermal model for molten silicon in a Czochralski crystal puller system with an applied uniform axial magnetic field. The melt depth is treated as continually decreasing, which affects the thermal environment of the melt and crystal. The radiative heat loss and the input heat flux are treated as functions of time, with a constraint placed on the heat lost to the crystal from the melt. As the melt motion reaches a steady state rapidly, the temperature and flow fields are treated as instantaneously steady at each melt depth. The heat transport is a mixture of conduction and convection, and by considering the crystal and crucible to be rotating with the same angular velocity, the flows driven by buoyancy and thermocapillarity are isolated and provide the convective heat transport in the melt for the range of magnetic field strengths 0.2 ≤ B ≤ 1.0T.

  13. Field study of thermal comfort in non-air-conditioned buildings in a tropical island climate.

    Science.gov (United States)

    Lu, Shilei; Pang, Bo; Qi, Yunfang; Fang, Kun

    2018-01-01

    The unique geographical location of Hainan makes its climate characteristics different from inland areas in China. The thermal comfort of Hainan also owes its uniqueness to its tropical island climate. In the past decades, there have been very few studies on thermal comfort of the residents in tropical island areas in China. A thermal environment test for different types of buildings in Hainan and a thermal comfort field investigation of 1944 subjects were conducted over a period of about two months. The results of the survey data show that a high humidity environment did not have a significant impact on human comfort. The neutral temperature for the residents in tropical island areas was 26.1 °C, and the acceptable temperature range of thermal comfort was from 23.1 °C to 29.1 °C. Residents living in tropical island areas showed higher heat resistance capacity, but lower cold tolerance than predicted. The neutral temperature for females (26.3 °C) was higher than for males (25.8 °C). Additionally, females were more sensitive to air temperature than males. The research conclusions can play a guiding role in the thermal environment design of green buildings in Hainan Province. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2016-04-01

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

  15. Techno-Economic Assessment of Heat Transfer Fluid Buffering for Thermal Energy Storage in the Solar Field of Parabolic Trough Solar Thermal Power Plants

    Directory of Open Access Journals (Sweden)

    Jorge M. Llamas

    2017-08-01

    Full Text Available Currently, operating parabolic trough (PT solar thermal power plants, either solar-only or with thermal storage block, use the solar field as a heat transfer fluid (HTF thermal storage system to provide extra thermal capacity when it is needed. This is done by circulating heat transfer fluid into the solar field piping in order to create a heat fluid buffer. In the same way, by oversizing the solar field, it can work as an alternative thermal energy storage (TES system to the traditionally applied methods. This paper presents a solar field TES model for a standard solar field from a 50-MWe solar power plant. An oversized solar model is analyzed to increase the capacity storage system (HTF buffering. A mathematical model has been developed and different simulations have been carried out over a cycle of one year with six different solar multiples considered to represent the different oversized solar field configurations. Annual electricity generation and levelized cost of energy (LCOE are calculated to find the solar multiple (SM which makes the highest solar field thermal storage capacity possible within the minimum LCOE.

  16. Dosimeter incorporating radiophotoluminescent detectors for thermal neutrons and γ-rays in n-γ fields

    Energy Technology Data Exchange (ETDEWEB)

    Salem, Y.O. [Groupe RaMsEs, Institut Pluridisciplinaire Hubert Curien (IPHC), UMR 7178 CNRS/IN2P3, 23 rue du Loess, BP 28, F-67037 Strasbourg Cedex 2 (France); Nachab, A., E-mail: a.nachab@uca.ma [Département de physique, Faculté Poly-disciplinaire, Université Cadi Ayyad, Route Sidi Bouzid BP 4162, 46000 Safi (Morocco); Roy, C.; Nourreddine, A. [Groupe RaMsEs, Institut Pluridisciplinaire Hubert Curien (IPHC), UMR 7178 CNRS/IN2P3, 23 rue du Loess, BP 28, F-67037 Strasbourg Cedex 2 (France)

    2016-10-15

    We have developed a dosimeter associating different neutron converters with two radiophotoluminescent detectors to measure thermal neutrons and γ-rays in a mixed n-γ field. Tests show that the H{sup ∗}(10) and H{sub p}(10) responses to thermal neutrons and γ-rays are linear with detection limits lower than 0.4 mSv. The angular dependence of the dosimeter response is satisfactory and the influence of a phantom on the results is examined.

  17. Energy-momentum tensor in thermal strong-field QED with unstable vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Gavrilov, S P [Department of General and Experimental Physics, Herzen State Pedagogical University of Russia, Moyka emb. 48, 191186 St Petersburg (Russian Federation); Gitman, D M [Instituto de Fisica, Universidade de Sao Paulo, CP 66318, CEP 05315-970 Sao Paulo, SP (Brazil)], E-mail: gavrilovsergeyp@yahoo.com, E-mail: gitman@dfn.if.usp.br

    2008-04-25

    The mean value of the one-loop energy-momentum tensor in thermal QED with an electric-like background that creates particles from vacuum is calculated. The problem is essentially different from calculations of effective actions (similar to the action of Heisenberg-Euler) in backgrounds that respect the stability of vacuum. The role of a constant electric background in the violation of both the stability of vacuum and the thermal character of particle distribution is investigated. Restrictions on the electric field and the duration over which one can neglect the back-reaction of created particles are established.

  18. Energy-momentum tensor in thermal strong-field QED with unstable vacuum

    International Nuclear Information System (INIS)

    Gavrilov, S P; Gitman, D M

    2008-01-01

    The mean value of the one-loop energy-momentum tensor in thermal QED with an electric-like background that creates particles from vacuum is calculated. The problem is essentially different from calculations of effective actions (similar to the action of Heisenberg-Euler) in backgrounds that respect the stability of vacuum. The role of a constant electric background in the violation of both the stability of vacuum and the thermal character of particle distribution is investigated. Restrictions on the electric field and the duration over which one can neglect the back-reaction of created particles are established

  19. The field fluctuational model of thermally stimulated processes in ferroelectric LiNbO3

    International Nuclear Information System (INIS)

    Tale, I.; Tale, V.; Rosa, J.

    1983-01-01

    The thermally stimulated processes in the x-irradiated LiNbO 3 crystals were studied by the fractional glow technique. The trap ionization with unusually high values of the mean activation energy and the effective frequency factor as well as decreasing the activation energy of the traps when the temperature increased from 150-180 K were observed. It is suggested that all these effects are due to the ion-fluctuation process (the electric field generated by thermal reorientation of dipoles). (author)

  20. Enhancement of single mode operation in coaxial optical waveguide using DB boundary conditions

    Science.gov (United States)

    Lohia, Pooja; Prajapati, Y.; Saini, J. P.; Rai, B. S.

    2014-11-01

    In this study, a competent numerical strategy to compute the dispersion of optical waveguides is presented and propagation of electromagnetic waves in a coaxial optical waveguide with DB boundary conditions is instigated. For this intend, cylindrical coordinates are here being used to derive the DB boundary conditions and to obtain field components for the modes. The propagation constant for the waveguide to be studied is determined by solving the Bessel and the modified Bessel functions. The cutoff frequencies for various lower order modes have been calculated and their dispersion characteristics are plotted correspondingly. The behavior of the coaxial optical waveguide under DB boundary conditions is shown to be significantly different from that of coaxial optical waveguide and conventional optical waveguide under traditional or tangential boundary conditions. Finally, the effect of waveguide dimensions on the mode cutoff frequencies and fabrication issues are also addressed.

  1. Fully quantum-mechanical dynamic analysis of single-photon transport in a single-mode waveguide coupled to a traveling-wave resonator

    International Nuclear Information System (INIS)

    Hach, Edwin E. III; Elshaari, Ali W.; Preble, Stefan F.

    2010-01-01

    We analyze the dynamics of single-photon transport in a single-mode waveguide coupled to a micro-optical resonator by using a fully quantum-mechanical model. We examine the propagation of a single-photon Gaussian packet through the system under various coupling conditions. We review the theory of single-photon transport phenomena as applied to the system and we develop a discussion on the numerical technique we used to solve for dynamical behavior of the quantized field. To demonstrate our method and to establish robust single-photon results, we study the process of adiabatically lowering or raising the energy of a single photon trapped in an optical resonator under active tuning of the resonator. We show that our fully quantum-mechanical approach reproduces the semiclassical result in the appropriate limit and that the adiabatic invariant has the same form in each case. Finally, we explore the trapping of a single photon in a system of dynamically tuned, coupled optical cavities.

  2. Analytical study of nonlinear phase shift through stimulated Brillouin scattering in single mode fiber with the pump power recycling technique

    International Nuclear Information System (INIS)

    Al-Asadi, H A; Mahdi, M A; Bakar, A A A; Adikan, F R Mahamd

    2011-01-01

    We present a theoretical study of nonlinear phase shift through stimulated Brillouin scattering in single mode optical fiber. Analytical expressions describing the nonlinear phase shift for the pump and Stokes waves in the pump power recycling technique have been derived. The dependence of the nonlinear phase shift on the optical fiber length, the reflectivity of the optical mirror and the frequency detuning coefficient have been analyzed for different input pump power values. We found that with the recycling pump technique, the nonlinear phase shift due to stimulated Brillouin scattering reduced to less than 0.1 rad for 5 km optical fiber length and 0.65 reflectivity of the optical mirror, respectively, at an input pump power equal to 30 mW

  3. Statistical properties of single-mode fiber coupling of satellite-to-ground laser links partially corrected by adaptive optics.

    Science.gov (United States)

    Canuet, Lucien; Védrenne, Nicolas; Conan, Jean-Marc; Petit, Cyril; Artaud, Geraldine; Rissons, Angelique; Lacan, Jerome

    2018-01-01

    In the framework of satellite-to-ground laser downlinks, an analytical model describing the variations of the instantaneous coupled flux into a single-mode fiber after correction of the incoming wavefront by partial adaptive optics (AO) is presented. Expressions for the probability density function and the cumulative distribution function as well as for the average fading duration and fading duration distribution of the corrected coupled flux are given. These results are of prime interest for the computation of metrics related to coded transmissions over correlated channels, and they are confronted by end-to-end wave-optics simulations in the case of a geosynchronous satellite (GEO)-to-ground and a low earth orbit satellite (LEO)-to-ground scenario. Eventually, the impact of different AO performances on the aforementioned fading duration distribution is analytically investigated for both scenarios.

  4. Experimental demonstration of a simple displacement sensor based on a bent single-mode–multimode–single-mode fiber structure

    International Nuclear Information System (INIS)

    Wu, Qiang; Semenova, Yuliya; Wang, Pengfei; Hatta, Agus Muhamad; Farrell, Gerald

    2011-01-01

    A simple displacement sensor based on a bent single-mode–multimode–single-mode (SMS) fiber structure is proposed and experimentally investigated. The sensor offers a wider displacement range, not limited by the risk of fiber breakage, as well as a three-fold increase in displacement sensitivity by comparison with a straight SMS structure sensor. This sensor can be interrogated by either an optical spectral analyzer (OSA) or a ratiometric interrogation system: (1) if interrogated by an OSA assuming a resolution of 1 pm, it has a sensitivity of 28.2 nm for a displacement measurement range from 0 to 280 µm; (2) if interrogated by a ratiometric interrogation system, it has worst and best case resolutions of 556 and 38 nm, respectively, for a displacement measurement range from 0 to 520 µm

  5. Efficient single-mode operation of a cladding-pumped ytterbium-doped helical-core fiber laser.

    Science.gov (United States)

    Wang, P; Cooper, L J; Sahu, J K; Clarkson, W A

    2006-01-15

    A novel approach to achieving robust single-spatial-mode operation of cladding-pumped fiber lasers with multimode cores is reported. The approach is based on the use of a fiber geometry in which the core has a helical trajectory within the inner cladding to suppress laser oscillation on higher-order modes. In a preliminary proof-of-principle study, efficient single-mode operation of a cladding-pumped ytterbium-doped helical-core fiber laser with a 30 microm diameter core and a numerical aperture of 0.087 has been demonstrated. The laser yielded 60.4 W of output at 1043 nm in a beam with M2 clad fiber lasers.

  6. Transmission of 2.5 Gbit/s Spectrum-sliced WDM System for 50 km Single-mode Fiber

    Science.gov (United States)

    Ahmed, Nasim; Aljunid, Sayed Alwee; Ahmad, R. Badlisha; Fadil, Hilal Adnan; Rashid, Mohd Abdur

    2011-06-01

    The transmission of a spectrum-sliced WDM channel at 2.5 Gbit/s for 50 km of single mode fiber using an system channel spacing only 0.4 nm is reported. We have investigated the system performance using NRZ modulation format. The proposed system is compared with conventional system. The system performance is characterized as the bit-error-rate (BER) received against the system bit rates. Simulation results show that the NRZ modulation format performs well for 2.5 Gbit/s system bit rates. Using this narrow channel spectrum-sliced technique, the total number of multiplexed channels can be increased greatly in WDM system. Therefore, 0.4 nm channel spacing spectrum-sliced WDM system is highly recommended for the long distance optical access networks, like the Metro Area Network (MAN), Fiber-to-the-Building (FTTB) and Fiber-to-the-Home (FTTH).

  7. High-temperature sensor based on an abrupt-taper Michelson interferometer in single-mode fiber.

    Science.gov (United States)

    Xu, Le; Jiang, Lan; Wang, Sumei; Li, Benye; Lu, Yongfeng

    2013-04-01

    This study proposes a high-temperature sensor based on an abrupt fiber-taper Michelson interferometer (FTMI) in single-mode fiber fabricated by a fiber-taper machine and electric-arc discharge. The proposed FTMI is applied to measure temperature and refractive index (RI). A high temperature sensitivity of 118.6 pm/°C is obtained in the temperature range of 500°C-800°C. The wavelength variation is only -0.335 nm for the maximum attenuation peak, with the external RI changed from 1.333 to 1.3902, which is desirable for high-temperature sensing to eliminate the cross sensitivity to RI.

  8. Stochastic resonance driven by time-modulated correlated coloured noise sources in a single-mode laser

    International Nuclear Information System (INIS)

    De-Yi, Chen; Li, Zhang

    2009-01-01

    This paper investigates the phenomenon of stochastic resonance in a single-mode laser driven by time-modulated correlated coloured noise sources. The power spectrum and signal-to-noise ratio R of the laser intensity are calculated by the linear approximation. The effects caused by noise self-correlation time τ 1 , τ 2 and cross-correlated time τ 3 for stochastic resonance are analysed in two ways: τ 1 , τ 2 and τ 3 are taken to be the independent variables and the parameters respectively. The effects of the gain coefficient Γ and loss coefficient K on the stochastic resonance are also discussed. It is found that besides the presence of the standard form and the broad sense of stochastic resonance, the number of extrema in the curve of R versus K is reduced with the increase of the gain coefficient Γ

  9. A design study on hyper-thermal neutron irradiation field for neutron capture therapy at Kyoto University Reactor

    International Nuclear Information System (INIS)

    Sakurai, Y.; Kobayashi, T.

    2000-01-01

    A study about the installation of a hyper-thermal neutron converter to a clinical collimator was performed, as a series of the design study on a hyper-thermal neutron irradiation field at the Heavy Water Neutron Irradiation Facility of Kyoto University Reactor. From the parametric-surveys by Monte Carlo calculation, it was confirmed that the practical irradiation field of hyper-thermal neutrons would be feasible by the modifications of the clinical collimator and the bismuth-layer structure. (author)

  10. The Density Matrix for Single-mode Light after k-Photon Absorption

    Science.gov (United States)

    Voigt, H.; Bandilla, A.

    In order to continue and generalize the studies of the density matrix of a light field undergoing k-photon absorption, in this paper we put the emphasis on the off-diagonal elements. The solution obtained earlier for the diagonal elements describing the photon statistics can be found as a special case but will not be discussed again. The general solution calculated by recursion shows an asymptotic behaviour if the initial photon number is sufficiently high. Only the initial phase information survives. Illustrating the solution we start with coherent light and a generalized coherent state.Translated AbstractDie Dichtematrix eines Lichtstrahls nach k-Photonen-Absorption aus einer ModeWir führen die Betrachtungen über das Verhalten der Dichtematrix eines Lichtfeldes nach k-Photonen-Absorption aus einer Mode verallgemeinernd weiter und konzentrieren uns auf die Nichtdiagonalelemente. Die im folgenden angegebene allgemeine Lösung, die durch Rekursion gefunden wurde, enthält die schon früher erhaltene, jedoch hier nicht weiter diskutierte Lösung für die Diagonalelemente als Spezialfall. Sie zeigt ferner, daß es einen asymptotischen Zustand gibt, der eine von der Ausgangsintensität unabhängige Information über die Ausgangsphase enthält. Zur Diskussion der Lösung werden verschiedene Anfangsbedingungen betrachtet, so z. B. kohärentes Licht und kohärentes Licht, das ein Medium mit nichtlinearem Brechungsindex durchlaufen hat (Kerr-Effekt).

  11. Sensor system for multi-point monitoring using bending loss of single mode optical fiber

    International Nuclear Information System (INIS)

    Kim, Heon Young; Kim, Dae Hyun

    2015-01-01

    Applications of smart sensors have been extended to safety systems in the aerospace, transportation and civil engineering fields. In particular, structural health monitoring techniques using smart sensors have gradually become necessary and have been developed to prevent dangers to human life and damage to assets. Generally, smart sensors are based on electro-magnets and have several weaknesses, including electro-magnetic interference and distortion. Therefore, fiber optic sensors are an outstanding alternative to overcome the weaknesses of electro-magnetic sensors. However, they require expensive devices and complex systems. This paper proposes a new, affordable and simple sensor system that uses a single fiber to monitor pressures at multiple-points. Moreover, a prototype of the sensor system was manufactured and tested for a feasibility study. Based on the results of this experimental test, a relationship was carefully observed between the bend loss conditions and light-intensity. As a result, it was shown that impacts at multiple-points could be monitored.

  12. PIV and LIF study of flow and thermal fields of twine plumes in water

    Science.gov (United States)

    Broučková, Zuzana; Trávníček, Zdeněk

    Flow and thermal fields of a pair of plane plumes in water are investigated by means of PIV and LIF experiments. The plumes are generated from thermal line sources, which are made out of electrically heated cylinders with a diameter of D = 1.21 mm. A cylinder-to-cylinder distance was 17.9 D. Either continuous or pulsating heating were used with the same heating input power. Because the cylinder-to-cylinder distance is moderately small, deflections of plumes from a vertical direction occur and the plumes are inclined together. This behavior is caused by a confined entrainment from a space between the both plumes. For a continuous heating, low frequency oscillations were identified and the natural frequency was evaluated as 0.5 Hz. Based on this finding, pulsating heating was used at the subharmonic frequency of 0.25 Hz. The maximum time-mean velocity magnitude at the continuous and pulsating heating were commensurable, approximately 0.007 m/s. On the other hand, pulsating heating achieves by 36 % higher velocity peaks. A very strong velocity oscillations were generated by pulsating heating at the distance approximately 8.3 D above the cylinders, where the velocity maxima oscillate along the time-mean value of 0.0057 m/s from -30% to +70 %. Temperature fields reasonably agree with this findings, despite a relatively fast equalization of the temperature field was concluded. The results demonstrate enhancement effects of pulsations in flow/thermal fields.

  13. Reproducibility of TL measurements in a mixed field of thermal neutrons and photons

    International Nuclear Information System (INIS)

    Fernandes, A.C.; Goncalves, I.C.; Ferro Carvalho, A.; Santos, J.; Cardoso, J.; Santos, L.; Osvay, M.

    2002-01-01

    The reproducibility of measurements performed with GR-100 (LiF:Mg,Ti) from the Solid Dosimetric Detector and Method Laboratory (DML) China, GR-107 ( 7 LiF:Mg,Ti, DML), TLD-700H ( 7 LiF:Mg,Cu,P, Harshaw) and Al 2 O 3 :Mg,Y (Hungary) in photon and mixed photon-neutron fields was investigated. Mixed-field irradiations were performed in a thermal neutron field generated at a nuclear reactor. GR-100 sensitivity decreased after mixed-field irradiations, while no significant change was found for the other materials. Using GR-100 for the dosimetry of mixed and high-intensity fields requires careful procedures. (author)

  14. Analytical approach for evaluating temperature field of thermal modified asphalt pavement and urban heat island effect

    International Nuclear Information System (INIS)

    Chen, Jiaqi; Wang, Hao; Zhu, Hongzhou

    2017-01-01

    Highlights: • Derive an analytical approach to predict temperature fields of multi-layered asphalt pavement based on Green’s function. • Analyze the effects of thermal modifications on heat output from pavement to near-surface environment. • Evaluate pavement solutions for reducing urban heat island (UHI) effect. - Abstract: This paper aims to present an analytical approach to predict temperature fields in asphalt pavement and evaluate the effects of thermal modification on near-surface environment for urban heat island (UHI) effect. The analytical solution of temperature fields in the multi-layered pavement structure was derived with the Green’s function method, using climatic factors including solar radiation, wind velocity, and air temperature as input parameters. The temperature solutions were validated with an outdoor field experiment. By using the proposed analytical solution, temperature fields in the pavement with different pavement surface albedo, thermal conductivity, and layer combinations were analyzed. Heat output from pavement surface to the near-surface environment was studied as an indicator of pavement contribution to UHI effect. The analysis results show that increasing pavement surface albedo could decrease pavement temperature at various depths, and increase heat output intensity in the daytime but decrease heat output intensity in the nighttime. Using reflective pavement to mitigate UHI may be effective for an open street but become ineffective for the street surrounded by high buildings. On the other hand, high-conductivity pavement could alleviate the UHI effect in the daytime for both the open street and the street surrounded by high buildings. Among different combinations of thermal-modified asphalt mixtures, the layer combination of high-conductivity surface course and base course could reduce the maximum heat output intensity and alleviate the UHI effect most.

  15. Thermal conductivity of bulk GaN—Effects of oxygen, magnesium doping, and strain field compensation

    International Nuclear Information System (INIS)

    Simon, Roland B.; Anaya, Julian; Kuball, Martin

    2014-01-01

    The effect of oxygen doping (n-type) and oxygen (O)-magnesium (Mg) co-doping (semi-insulating) on the thermal conductivity of ammonothermal bulk GaN was studied via 3-omega measurements and a modified Callaway model. Oxygen doping was shown to significantly reduce thermal conductivity, whereas O-Mg co-doped GaN exhibited a thermal conductivity close to that of undoped GaN. The latter was attributed to a decreased phonon scattering rate due the compensation of impurity-generated strain fields as a result of dopant-complex formation. The results have great implications for GaN electronic and optoelectronic device applications on bulk GaN substrates

  16. Three-dimensional temperature field model of thermally decomposing resin composite irradiated by laser

    International Nuclear Information System (INIS)

    Chen Minsun; Jiang Houman; Liu Zejin

    2011-01-01

    Fundamental equations governing the temperature field of thermally decomposing resin composite irradiated by laser are derived from mass and energy conservation laws with the control Janume method. The thermal decomposition of resin is described by a multi-step model. An assumption is proposed that the flow of pyrolysis gas is one-dimensional, which makes it possible to consider the influence of pyrolysis gas convective transport and realize the closure of the three-dimensional model without introducing mechanical quantities. In view of the anisotropy of resin composite, expressions of the thermal conductivities of partially pyrolyzed material are deduced, as well as the computing formula for the laser absorption coefficient of partially pyrolyzed material. The energy conservation equation is consistent with reference under some simplifications. (authors)

  17. On the stringy nature of winding modes in noncommutative thermal field theories

    CERN Document Server

    Arcioni, G; Gomis, J P; Vázquez-Mozo, Miguel Angel; Gomis, Joaquim

    2000-01-01

    We show that thermal noncommutative field theories admit a version of `channel duality' reminiscent of open/closed string duality, where non-planar thermal loops can be replaced by an infinite tower of tree-level exchanges of effective fields. These effective fields resemble closed strings in three aspects: their mass spectrum is that of closed-string winding modes, their interaction vertices contain extra moduli, and they can be regarded as propagating in a higher-dimensional `bulk' space-time. In noncommutative models that can be embedded in a D-brane, we show the precise relation between the effective `winding fields' and closed strings propagating off the D-brane. The winding fields represent the coherent coupling of the infinite tower of closed-string oscillator states. We derive a sum rule that expresses this effective coupling in terms of the elementary couplings of closed strings to the D-brane. We furthermore clarify the relation between the effective propagating dimension of the winding fields and t...

  18. Passenger thermal comfort and behavior: a field investigation in commercial aircraft cabins.

    Science.gov (United States)

    Cui, W; Wu, T; Ouyang, Q; Zhu, Y

    2017-01-01

    Passengers' behavioral adjustments warrant greater attention in thermal comfort research in aircraft cabins. Thus, a field investigation on 10 commercial aircrafts was conducted. Environment measurements were made and a questionnaire survey was performed. In the questionnaire, passengers were asked to evaluate their thermal comfort and record their adjustments regarding the usage of blankets and ventilation nozzles. The results indicate that behavioral adjustments in the cabin and the use of blankets or nozzle adjustments were employed by 2/3 of the passengers. However, the thermal comfort evaluations by these passengers were not as good as the evaluations by passengers who did not perform any adjustments. Possible causes such as differences in metabolic rate, clothing insulation and radiation asymmetry are discussed. The individual difference seems to be the most probable contributor, suggesting possibly that passengers who made adjustments had a narrower acceptance threshold or a higher expectancy regarding the cabin environment. Local thermal comfort was closely related to the adjustments and significantly influenced overall thermal comfort. Frequent flying was associated with lower ratings for the cabin environment. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Dispersed solar thermal generation employing parabolic dish-electric transport with field modulated generator systems

    Science.gov (United States)

    Ramakumar, R.; Bahrami, K.

    1981-01-01

    This paper discusses the application of field modulated generator systems (FMGS) to dispersed solar-thermal-electric generation from a parabolic dish field with electric transport. Each solar generation unit is rated at 15 kWe and the power generated by an array of such units is electrically collected for insertion into an existing utility grid. Such an approach appears to be most suitable when the heat engine rotational speeds are high (greater than 6000 r/min) and, in particular, if they are operated in the variable speed mode and if utility-grade a.c. is required for direct insertion into the grid without an intermediate electric energy storage and reconversion system. Predictions of overall efficiencies based on conservative efficiency figures for the FMGS are in the range of 25 per cent and should be encouraging to those involved in the development of cost-effective dispersed solar thermal power systems.

  20. Thermal instabilities in the edge region of reversed-field pinches

    International Nuclear Information System (INIS)

    Goedert, J.; Mondt, J.P.

    1984-04-01

    Thermal stability of the edge region of reversed-field pinch configurations is analyzed within the context of a two-fluid model. Two major sources of instability are identified in combination with a parallel electric field: either an electron temperature gradient and/or a density gradient that leads to rapid growth (of several to many ohmic heating rates) over a region of several millimeters around the mode-rational surfaces in the edge region. The basic signature of both instabilities is electrostatic. In the case of the density gradient mode, the signature relies on the effects of electron compressibility, whereas the temperature gradient mode can be identified as the current-convective instability by taking the limit of zero diamagnetic drift, density gradient, thermal force, drift heat flux, and electron compressibility

  1. Suppression of thermal noise in a non-Markovian random velocity field

    International Nuclear Information System (INIS)

    Ueda, Masahiko

    2016-01-01

    We study the diffusion of Brownian particles in a Gaussian random velocity field with short memory. By extending the derivation of an effective Fokker–Planck equation for the Lanvegin equation with weakly colored noise to a random velocity-field problem, we find that the effect of thermal noise on particles is suppressed by the existence of memory. We also find that the renormalization effect for the relative diffusion of two particles is stronger than that for single-particle diffusion. The results are compared with those of molecular dynamics simulations. (paper: classical statistical mechanics, equilibrium and non-equilibrium)

  2. Decoherence and thermalization of a pure quantum state in quantum field theory.

    Science.gov (United States)

    Giraud, Alexandre; Serreau, Julien

    2010-06-11

    We study the real-time evolution of a self-interacting O(N) scalar field initially prepared in a pure, coherent quantum state. We present a complete solution of the nonequilibrium quantum dynamics from a 1/N expansion of the two-particle-irreducible effective action at next-to-leading order, which includes scattering and memory effects. We demonstrate that, restricting one's attention (or ability to measure) to a subset of the infinite hierarchy of correlation functions, one observes an effective loss of purity or coherence and, on longer time scales, thermalization. We point out that the physics of decoherence is well described by classical statistical field theory.

  3. Non-thermal continuous and modulated electromagnetic radiation fields effects on sleep EEG of rats ?

    OpenAIRE

    Mohammed, Haitham S.; Fahmy, Heba M.; Radwan, Nasr M.; Elsayed, Anwar A.

    2012-01-01

    In the present study, the alteration in the sleep EEG in rats due to chronic exposure to low-level non-thermal electromagnetic radiation was investigated. Two types of radiation fields were used; 900 MHz unmodulated wave and 900 MHz modulated at 8 and 16 Hz waves. Animals has exposed to radiation fields for 1 month (1 h/day). EEG power spectral analyses of exposed and control animals during slow wave sleep (SWS) and rapid eye movement sleep (REM sleep) revealed that the REM sleep is more susc...

  4. The effect of electron thermal conduction on plasma pressure gradient during reconnection of magnetic field lines

    International Nuclear Information System (INIS)

    Chu, T.K.

    1987-12-01

    The interplay of electron cross-field thermal conduction and the reconnection of magnetic field lines around an m = 1 magnetic island prior to a sawtooth crash can generate a large pressure gradient in a boundary layer adjacent to the reconnecting surface, leading to an enhanced gradient of poloidal beta to satisfy the threshold condition for ideal MHD modes. This narrow boundary layer and the short onset time of a sawtooth crash can be supported by fine-grained turbulent processes in a tokamak plasma. 11 refs

  5. Hard Thermal Loop approximation in the Light Front Quantum Field Theory

    International Nuclear Information System (INIS)

    Silva, Charles da Rocha; Perez, Silvana

    2011-01-01

    Full text: In this paper we generalize the Hard Thermal Loop approximation (HTL) for the Thermal Light Front Quantum Field Theory. This technique was developed by Braaten e Pisarski [PRL. 63 (1989) 1129, Nucl. Phys. B337 (1990) 569], for the Thermal Quantum Field Theory at equal time and is particularly useful to solve problems of convergence of the amplitudes within Quantum Chromodynamics, caused by the inherently nonperturbative behavior. The HTL approximation satisfies simple Ward identities, is ultraviolet finite and gauge independent. Here we use the light front generalized coordinates (GLFC) proposed by one of us (V. S. Alves, Ashok Das, e Silvana Perez [PRD. 66, (2002) 125008]) and analyze the one loop amplitudes for the λφ3 theory and the Quantum Electrodynamics in (3+1) dimensions at finite temperature in the HTL approximation. For the scalar theory, we evaluate the two-point function, recovering the usual dispersion relations. We also analyze the rotational invariance of the model. We then consider the Quantum Electrodynamics in (3+1) dimensions and calculate the polarization tensor and the vertex function at finite temperature in the HTL approximation. In future, our interest will be to apply the Generalized Light Front formalism to understand the confinement mechanism which occurs in the Quantum Chromodynamics. There is an expectation that the Light Front Quantum Field Theory formalism is more appropriate to study this problems. (author)

  6. Hard Thermal Loop approximation in the Light Front Quantum Field Theory

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Charles da Rocha [Instituto Federal de Educacao, Ciencia e Tecnologia do Para (IFPA), Belem, PA (Brazil); Universidade Federal do Para (UFPA), Belem, PA (Brazil); Perez, Silvana [Universidade Federal do Para (UFPA), Belem, PA (Brazil)

    2011-07-01

    Full text: In this paper we generalize the Hard Thermal Loop approximation (HTL) for the Thermal Light Front Quantum Field Theory. This technique was developed by Braaten e Pisarski [PRL. 63 (1989) 1129, Nucl. Phys. B337 (1990) 569], for the Thermal Quantum Field Theory at equal time and is particularly useful to solve problems of convergence of the amplitudes within Quantum Chromodynamics, caused by the inherently nonperturbative behavior. The HTL approximation satisfies simple Ward identities, is ultraviolet finite and gauge independent. Here we use the light front generalized coordinates (GLFC) proposed by one of us (V. S. Alves, Ashok Das, e Silvana Perez [PRD. 66, (2002) 125008]) and analyze the one loop amplitudes for the {lambda}{phi}3 theory and the Quantum Electrodynamics in (3+1) dimensions at finite temperature in the HTL approximation. For the scalar theory, we evaluate the two-point function, recovering the usual dispersion relations. We also analyze the rotational invariance of the model. We then consider the Quantum Electrodynamics in (3+1) dimensions and calculate the polarization tensor and the vertex function at finite temperature in the HTL approximation. In future, our interest will be to apply the Generalized Light Front formalism to understand the confinement mechanism which occurs in the Quantum Chromodynamics. There is an expectation that the Light Front Quantum Field Theory formalism is more appropriate to study this problems. (author)

  7. 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.

  8. Thermal and mechanical effects of quenches on Nb3Sn high field hadron collider magnets

    International Nuclear Information System (INIS)

    Ryuji, Yamada

    2001-01-01

    Thermal and its resulting mechanical stress due to quenches inside short and long epoxy impregnated Nb 3 Sn high field magnets are studied with a quench simulation program, Kuench, and ANSYS program. For the protection of a long high field magnet, we have to use heaters to dump the stored energy uniformly inside the magnet, after detection of a spontaneous quench. The time delay of starting a forced quench with heaters, is estimated using ANSYS. Using this information, the thermal distribution in two-dimensional magnet cross section is studied. First a one meter model magnet with a dump resistor is used to estimate the effects and then a 10 meter long magnet is studied. The two-dimensional temperature distributions in the magnet cross sections are recorded every 5 ms, and visually displayed. With this visual animation displays we can understand intuitively the thermal and quench propagation in 2-dimensional field. The quenching cables get heated locally much more than the surrounding material and non-quenching conductor cables. With a one meter magnet with a dump resistor of 30 mOmega, typically only the quench starting cables and its neighbor cables get heated up to 100 K without significant effects from the heaters. With a10 meter magnet, heaters cause the quenches to most of the conductor blocks. The quench initiating cables get up to 250 to 300 K in 100 ms, but the surrounding and wedges are not heated up significantly. This causes the excessive stress in the quenching conductors and in their insulation material locally. The stress and strain in the conductor as well as in the insulation become excessive, and they are studied using the ANSYS stress analysis, using Von Mises criterion. It is concluded that for the one meter magnet with the presented cross section and configuration, the thermal effects due to the quench is tolerable. But we need much more quench study and improvements in the design for the extended ten meter long magnet [1

  9. Experimental Study of Thermal Field Evolution in the Short-Impending Stage Before Earthquakes

    Science.gov (United States)

    Ren, Yaqiong; Ma, Jin; Liu, Peixun; Chen, Shunyun

    2017-08-01

    Phenomena at critical points are vital for identifying the short-impending stage prior to earthquakes. The peak stress is a critical point when stress is converted from predominantly accumulation to predominantly release. We call the duration between the peak stress and instability "the meta-instability stage", which refers to the short-impending stage of earthquakes. The meta-instability stage consists of a steady releasing quasi-static stage and an accelerated releasing quasi-dynamic stage. The turning point of the above two stages is the remaining critical point. To identify the two critical points in the field, it is necessary to study the characteristic phenomena of various physical fields in the meta-instability stage in the laboratory, and the strain and displacement variations were studied. Considering that stress and relative displacement can be detected by thermal variations and peculiarities in the full-field observations, we employed a cooled thermal infrared imaging system to record thermal variations in the meta-instability stage of stick slip events generated along a simulated, precut planer strike slip fault in a granodiorite block on a horizontally bilateral servo-controlled press machine. The experimental results demonstrate the following: (1) a large area of decreasing temperatures in wall rocks and increasing temperatures in sporadic sections of the fault indicate entrance into the meta-instability stage. (2) The rapid expansion of regions of increasing temperatures on the fault and the enhancement of temperature increase amplitude correspond to the turning point from the quasi-static stage to the quasi-dynamic stage. Our results reveal thermal indicators for the critical points prior to earthquakes that provide clues for identifying the short-impending stage of earthquakes.

  10. 3D structure and conductive thermal field of the Upper Rhine Graben

    Science.gov (United States)

    Freymark, Jessica; Sippel, Judith; Scheck-Wenderoth, Magdalena; Bär, Kristian; Stiller, Manfred; Fritsche, Johann-Gerhard; Kracht, Matthias

    2016-04-01

    The Upper Rhine Graben (URG) was formed as part of the European Cenozoic Rift System in a complex extensional setting. At present-day, it has a large socioeconomic relevance as it provides a great potential for geothermal energy production in Germany and France. For the utilisation of this energy resource it is crucial to understand the structure and the observed temperature anomalies in the rift basin. In the framework of the EU-funded "IMAGE" project (Integrated Methods for Advanced Geothermal Exploration), we apply a data-driven numerical modelling approach to quantify the processes and properties controlling the spatial distribution of subsurface temperatures. Typically, reservoir-scale numerical models are developed for predictions on the subsurface hydrothermal conditions and for reducing the risk of drilling non-productive geothermal wells. One major problem related to such models is setting appropriate boundary conditions that define, for instance, how much heat enters the reservoir from greater depths. Therefore, we first build a regional lithospheric-scale 3D structural model, which covers not only the entire URG but also adjacent geological features like the Black Forest and the Vosges Mountains. In particular, we use a multidisciplinary dataset (e.g. well data, seismic reflection data, existing structural models, gravity) to construct the geometries of the sediments, the crust and the lithospheric mantle that control the spatial distribution of thermal conductivity and radiogenic heat production and hence temperatures. By applying a data-based and lithology-dependent parameterisation of this lithospheric-scale 3D structural model and a 3D finite element method, we calculate the steady-state conductive thermal field for the entire region. Available measured temperatures (down to depths of up to 5 km) are considered to validate the 3D thermal model. We present major characteristics of the lithospheric-scale 3D structural model and results of the 3D

  11. Thermal and hydraulic analyses of TFTR cooling water system and magnetic field coils

    International Nuclear Information System (INIS)

    Lee, A.Y.

    1975-10-01

    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 53 0 C; for the OH coils 46 0 C and for the EF coils 39 0 C, which are well below the coil design limit of 120 0 C. The maximum TF coil coolant temperature is 33 0 C which is below the coolant design limit of 100 0 C. The overall pressure loss of the system is below 6.89 x 10 5 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

  12. Field Measurements Indicate Unexpected, Serious Underestimation of Mussel Heart Rates and Thermal Tolerance by Laboratory Studies.

    Directory of Open Access Journals (Sweden)

    Morgana Tagliarolo

    Full Text Available Attempts to predict the response of species to long-term environmental change are generally based on extrapolations from laboratory experiments that inevitably simplify the complex interacting effects that occur in the field. We recorded heart rates of two genetic lineages of the brown mussel Perna perna over a full tidal cycle in-situ at two different sites in order to evaluate the cardiac responses of the two genetic lineages present on the South African coast to temperature and the immersion/emersion cycle. "Robomussel" temperature loggers were used to monitor thermal conditions at the two sites over one year. Comparison with live animals showed that robomussels provided a good estimate of mussel body temperatures. A significant difference in estimated body temperatures was observed between the sites and the results showed that, under natural conditions, temperatures regularly approach or exceed the thermal limits of P. perna identified in the laboratory. The two P. perna lineages showed similar tidal and diel patterns of heart rate, with higher cardiac activity during daytime immersion and minimal values during daytime emersion. Comparison of the heart rates measured in the field with data previously measured in the laboratory indicates that laboratory results seriously underestimate heart rate activity, by as much as 75%, especially during immersion. Unexpectedly, field estimates of body temperatures indicated an ability to tolerate temperatures considered lethal on the basis of laboratory measurements. This suggests that the interaction of abiotic conditions in the field does not necessarily raise vulnerability to high temperatures.

  13. Temperature field and thermal stress analysis of the HT-7U vacuum vessel

    International Nuclear Information System (INIS)

    Song Yuntao; Yao Damao; Wu Songtao; Weng Peide

    2000-01-01

    The HT-7U vacuum vessel is an all-metal-welded double-wall interconnected with toroidal and poloidal stiffening ribs. The channels formed between the ribs and walls are filled with boride water as a nuclear shielding. On the vessel surface facing the plasma are installed cable-based Ohmic heaters. Prior to plasma operation the vessel is to be baked out and discharge cleaned at about 250 degree C. During baking out the non-uniformity of temperature distribution on the vacuum vessel will bring about serious thermal stress that can damage the vessel. In order to determine and optimize the design of the HT-7U vacuum vessel, a three-dimensional finite element model was performed to analyse its temperature field and thermal stress. the maximal thermal stress appeared on the round of lower vertical port and maximal deformation located just on the region between the upper vertical port and the horizontal port. The results show that the reinforced structure has a good capability of withstanding the thermal loads

  14. Cerebral cortex classification by conditional random fields applied to intraoperative thermal imaging

    Directory of Open Access Journals (Sweden)

    Hoffmann Nico

    2016-09-01

    Full Text Available Intraoperative thermal neuroimaging is a novel intraoperative imaging technique for the characterization of perfusion disorders, neural activity and other pathological changes of the brain. It bases on the correlation of (sub-cortical metabolism and perfusion with the emitted heat of the cortical surface. In order to minimize required computational resources and prevent unwanted artefacts in subsequent data analysis workflows foreground detection is a important preprocessing technique to differentiate pixels representing the cerebral cortex from background objects. We propose an efficient classification framework that integrates characteristic dynamic thermal behaviour into this classification task to include additional discriminative features. The first stage of our framework consists of learning this representation of characteristic thermal time-frequency behaviour. This representation models latent interconnections in the time-frequency domain that cover specific, yet a priori unknown, thermal properties of the cortex. In a second stage these features are then used to classify each pixel’s state with conditional random fields. We quantitatively evaluate several approaches to learning high-level features and their impact to the overall prediction accuracy. The introduction of high-level features leads to a significant accuracy improvement compared to a baseline classifier.

  15. 107.5 Gb/s 850 nm multi- and single-mode VCSEL transmission over 10 and 100 m of multi-mode fiber

    DEFF Research Database (Denmark)

    Puerta Ramírez, Rafael; Agustin, M.; Chorchos, L.

    2016-01-01

    First time successful 107.5 Gb/s MultiCAP 850 nm OM4 MMF transmissions over 10 m with multi-mode VCSEL and up to 100 m with single-mode VCSEL are demonstrated, with BER below 7% overhead FEC limit measured for each case.......First time successful 107.5 Gb/s MultiCAP 850 nm OM4 MMF transmissions over 10 m with multi-mode VCSEL and up to 100 m with single-mode VCSEL are demonstrated, with BER below 7% overhead FEC limit measured for each case....

  16. Highly Sensitive Refractive Index Sensor Based on a Cladding-Etched Thin-Core Fiber Sandwiched between Two Single-Mode Fibers

    International Nuclear Information System (INIS)

    Xu Ben; Li Yi; Dong Xin-Yong; Jin Shang-Zhong; Zhang Zai-Xuan

    2012-01-01

    A refractive index (RI) sensor based on a cladding-etched thin-core single-mode fiber (TCSMF) sandwiched between two single-mode fibers is demonstrated. The experimental results show that the sensitivity, within the RI range of 1.333–1.340, is enhanced at least 6 times by etching. It increases with the surrounding RI and reaches 857.5 nm/RIU at RI of 1.3684, and it can be expected to be higher with the decrease of the cladding diameter of the TCSMF

  17. PIV and LIF study of flow and thermal fields of twine plumes in water

    Directory of Open Access Journals (Sweden)

    Broučková Zuzana

    2017-01-01

    Full Text Available Flow and thermal fields of a pair of plane plumes in water are investigated by means of PIV and LIF experiments. The plumes are generated from thermal line sources, which are made out of electrically heated cylinders with a diameter of D = 1.21 mm. A cylinder-to-cylinder distance was 17.9 D. Either continuous or pulsating heating were used with the same heating input power. Because the cylinder-to-cylinder distance is moderately small, deflections of plumes from a vertical direction occur and the plumes are inclined together. This behavior is caused by a confined entrainment from a space between the both plumes. For a continuous heating, low frequency oscillations were identified and the natural frequency was evaluated as 0.5 Hz. Based on this finding, pulsating heating was used at the subharmonic frequency of 0.25 Hz. The maximum time-mean velocity magnitude at the continuous and pulsating heating were commensurable, approximately 0.007 m/s. On the other hand, pulsating heating achieves by 36 % higher velocity peaks. A very strong velocity oscillations were generated by pulsating heating at the distance approximately 8.3 D above the cylinders, where the velocity maxima oscillate along the time-mean value of 0.0057 m/s from −30% to +70 %. Temperature fields reasonably agree with this findings, despite a relatively fast equalization of the temperature field was concluded. The results demonstrate enhancement effects of pulsations in flow/thermal fields.

  18. Thermal Sunyaev-Zel'dovich effect in the intergalactic medium with primordial magnetic fields

    Science.gov (United States)

    Minoda, Teppei; Hasegawa, Kenji; Tashiro, Hiroyuki; Ichiki, Kiyotomo; Sugiyama, Naoshi

    2017-12-01

    The presence of ubiquitous magnetic fields in the universe is suggested from observations of radiation and cosmic ray from galaxies or the intergalactic medium (IGM). One possible origin of cosmic magnetic fields is the magnetogenesis in the primordial universe. Such magnetic fields are called primordial magnetic fields (PMFs), and are considered to affect the evolution of matter density fluctuations and the thermal history of the IGM gas. Hence the information of PMFs is expected to be imprinted on the anisotropies of the cosmic microwave background (CMB) through the thermal Sunyaev-Zel'dovich (tSZ) effect in the IGM. In this study, given an initial power spectrum of PMFs as P (k )∝B1Mpc 2knB , we calculate dynamical and thermal evolutions of the IGM under the influence of PMFs, and compute the resultant angular power spectrum of the Compton y -parameter on the sky. As a result, we find that two physical processes driven by PMFs dominantly determine the power spectrum of the Compton y -parameter; (i) the heating due to the ambipolar diffusion effectively works to increase the temperature and the ionization fraction, and (ii) the Lorentz force drastically enhances the density contrast on small scale just after the recombination epoch. These facts result in making the anisotropies of the CMB temperature on small scales, and we find that the signal goes up to 10 μ K2 around ℓ˜106 with B1 Mpc=0.1 nG and nB=0.0 . Therefore, CMB measurements on such small scales may provide a hint for the existence of the PMFs.

  19. Non-thermal continuous and modulated electromagnetic radiation fields effects on sleep EEG of rats☆

    Science.gov (United States)

    Mohammed, Haitham S.; Fahmy, Heba M.; Radwan, Nasr M.; Elsayed, Anwar A.

    2012-01-01

    In the present study, the alteration in the sleep EEG in rats due to chronic exposure to low-level non-thermal electromagnetic radiation was investigated. Two types of radiation fields were used; 900 MHz unmodulated wave and 900 MHz modulated at 8 and 16 Hz waves. Animals has exposed to radiation fields for 1 month (1 h/day). EEG power spectral analyses of exposed and control animals during slow wave sleep (SWS) and rapid eye movement sleep (REM sleep) revealed that the REM sleep is more susceptible to modulated radiofrequency radiation fields (RFR) than the SWS. The latency of REM sleep increased due to radiation exposure indicating a change in the ultradian rhythm of normal sleep cycles. The cumulative and irreversible effect of radiation exposure was proposed and the interaction of the extremely low frequency radiation with the similar EEG frequencies was suggested. PMID:25685416

  20. Non-thermal continuous and modulated electromagnetic radiation fields effects on sleep EEG of rats

    Directory of Open Access Journals (Sweden)

    Haitham S. Mohammed

    2013-03-01

    Full Text Available In the present study, the alteration in the sleep EEG in rats due to chronic exposure to low-level non-thermal electromagnetic radiation was investigated. Two types of radiation fields were used; 900 MHz unmodulated wave and 900 MHz modulated at 8 and 16 Hz waves. Animals has exposed to radiation fields for 1 month (1 h/day. EEG power spectral analyses of exposed and control animals during slow wave sleep (SWS and rapid eye movement sleep (REM sleep revealed that the REM sleep is more susceptible to modulated radiofrequency radiation fields (RFR than the SWS. The latency of REM sleep increased due to radiation exposure indicating a change in the ultradian rhythm of normal sleep cycles. The cumulative and irreversible effect of radiation exposure was proposed and the interaction of the extremely low frequency radiation with the similar EEG frequencies was suggested.

  1. Development of thermal analysis method for the near field of HLW repository using ABAQUS

    Energy Technology Data Exchange (ETDEWEB)

    Kuh, Jung Eui; Kang, Chul Hyung; Park, Jeong Hwa [Korea Atomic Energy Research Institute, Taejon (Korea)

    1998-10-01

    An appropriate tool is needed to evaluate the thermo-mechanical stability of high level radioactive waste (HLW) repository. In this report a thermal analysis methodology for the near field of HLW repository is developed to use ABAQUS which is one of the multi purpose FEM code and has been used for many engineering area. The main contents of this methodology development are the structural and material modelling to simulate a repository, setup of side conditions, e.g., boundary and load conditions, and initial conditions, and the procedure to selection proper material parameters. In addition to these, the interface programs for effective production of input data and effective change of model size for sensitivity analysis for disposal concept development are developed. The results of this work will be apply to evaluate the thermal stability and to use as main input data for mechanical analysis of HLW repository. (author). 20 refs., 15 figs., 5 tabs.

  2. Influence of crystal field excitations on thermal and electrical resistivity of normal rare-earth metals

    Energy Technology Data Exchange (ETDEWEB)

    Durczewski, K.; Gajek, Z.; Mucha, J. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw (Poland)

    2014-11-15

    A simple formula describing the influence of the crystalline electric field free-ion excitations on the temperature dependence of the contribution of the s-f scattering to the thermal resistivity of normal rare-earth metals is presented. The corresponding formula for the electrical resistivity is also given and compared to the one being currently used. Theoretical electron-phonon scattering contributions derived in earlier papers and constant impurity scattering contributions are added to the derived s-f contribution formulae in order to fit the total electrical and thermal resistivity represented as functions of the temperature to experimental dependences on the temperature for DyIn{sub 3} and in this way to manifest applicability of the derived formulae to real materials. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Influence of crystal field excitations on thermal and electrical resistivity of normal rare-earth metals

    International Nuclear Information System (INIS)

    Durczewski, K.; Gajek, Z.; Mucha, J.

    2014-01-01

    A simple formula describing the influence of the crystalline electric field free-ion excitations on the temperature dependence of the contribution of the s-f scattering to the thermal resistivity of normal rare-earth metals is presented. The corresponding formula for the electrical resistivity is also given and compared to the one being currently used. Theoretical electron-phonon scattering contributions derived in earlier papers and constant impurity scattering contributions are added to the derived s-f contribution formulae in order to fit the total electrical and thermal resistivity represented as functions of the temperature to experimental dependences on the temperature for DyIn 3 and in this way to manifest applicability of the derived formulae to real materials. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Nambu-Goldstone mechanism in real-time thermal field theory

    International Nuclear Information System (INIS)

    Zhou Bangrong

    1998-08-01

    In a one-generation fermion condensate scheme of electroweak symmetry breaking, it is proven that at finite temperature T below the symmetry restoration temperature T c , a massive Higgs boson and three massless Nambu-Goldstone bosons could emerge from the spontaneous breaking of electroweak group SU L (2)xU Y (1)→U Q (1) if the two fermion flavors in the one generation are mass-degenerate, thus the Goldstone Theorem is rigorously valid in this case. However, if the two fermion flavors have unequal masses, owing to 'thermal fluctuation', the Goldstone Theorem will be true only approximately for a very large momentum cut-off Λ in zero temperature fermion loop or for low energy scales. All possible pinch singularities are proven to cancel each other, as is expected in a real-time thermal field theory. (author)

  5. Asymptotic approximation of laminar lubrication thermal field at low reduced peclet and Brinkman number

    DEFF Research Database (Denmark)

    Johansen, Per; Roemer, Daniel Beck; Andersen, Torben Ole

    2014-01-01

    A conventional simplification of the thermal problem in fluid film lubrication analysis is performed by assuming that the main direction of heat flow is conduction through the film thickness, and thereby neglecting convection. However, in a significant amount of applications, convection is not ne......A conventional simplification of the thermal problem in fluid film lubrication analysis is performed by assuming that the main direction of heat flow is conduction through the film thickness, and thereby neglecting convection. However, in a significant amount of applications, convection...... is not negligible, whereby the majority of design engineers exclusively use numerical solvers. This paper presents a perturbation series expansion of the temperature field for small values of the Brinkman number. The derived perturbation solution and the more conventional analytical solution, where convection...

  6. Adaptable Optical Fiber Displacement-Curvature Sensor Based on a Modal Michelson Interferometer with a Tapered Single Mode Fiber.

    Science.gov (United States)

    Salceda-Delgado, G; Martinez-Rios, A; Selvas-Aguilar, R; Álvarez-Tamayo, R I; Castillo-Guzman, A; Ibarra-Escamilla, B; Durán-Ramírez, V M; Enriquez-Gomez, L F

    2017-06-02

    A compact, highly sensitive optical fiber displacement and curvature radius sensor is presented. The device consists of an adiabatic bi-conical fused fiber taper spliced to a single-mode fiber (SMF) segment with a flat face end. The bi-conical taper structure acts as a modal coupling device between core and cladding modes for the SMF segment. When the bi-conical taper is bent by an axial displacement, the symmetrical bi-conical shape of the tapered structure is stressed, causing a change in the refractive index profile which becomes asymmetric. As a result, the taper adiabaticity is lost, and interference between modes appears. As the bending increases, a small change in the fringe visibility and a wavelength shift on the periodical reflection spectrum of the in-fiber interferometer is produced. The displacement sensitivity and the spectral periodicity of the device can be adjusted by the proper selection of the SMF length. Sensitivities from around 1.93 to 3.4 nm/mm were obtained for SMF length between 7.5 and 12.5 cm. Both sensor interrogations, wavelength shift and visibility contrast, can be used to measure displacement and curvature radius magnitudes.

  7. Biologically inspired flexible quasi-single-mode random laser: An integration of Pieris canidia butterfly wing and semiconductors

    Science.gov (United States)

    Wang, Cih-Su; Chang, Tsung-Yuan; Lin, Tai-Yuan; Chen, Yang-Fang

    2014-10-01

    Quasi-periodic structures of natural biomaterial membranes have great potentials to serve as resonance cavities to generate ecological friendly optoelectronic devices with low cost. To achieve the first attempt for the illustration of the underlying principle, the Pieris canidia butterfly wing was embedded with ZnO nanoparticles. Quite interestingly, it is found that the bio-inspired quasi-single-mode random laser can be achieved by the assistance of the skeleton of the membrane, in which ZnO nanoparticles act as emitting gain media. Such unique characteristics can be interpreted well by the Fabry-Perot resonance existing in the window-like quasi-periodic structure of butterfly wing. Due to the inherently promising flexibility of butterfly wing membrane, the laser action can still be maintained during the bending process. Our demonstrated approach not only indicates that the natural biological structures can provide effective scattering feedbacks but also pave a new avenue towards designing bio-controlled photonic devices.

  8. Long-Period Gratings in Highly Germanium-Doped, Single-Mode Optical Fibers for Sensing Applications

    Science.gov (United States)

    Schlangen, Sebastian; Bremer, Kort; Zheng, Yulong; Böhm, Sebastian; Steinke, Michael; Wellmann, Felix; Neumann, Jörg; Overmeyer, Ludger

    2018-01-01

    Long-period fiber gratings (LPGs) are well known for their sensitivity to external influences, which make them interesting for a large number of sensing applications. For these applications, fibers with a high numerical aperture (i.e., fibers with highly germanium (Ge)-doped fused silica fiber cores) are more attractive since they are intrinsically photosensitive, as well as less sensitive to bend- and microbend-induced light attenuations. In this work, we introduce a novel method to inscribe LPGs into highly Ge-doped, single-mode fibers. By tapering the optical fiber, and thus, tailoring the effective indices of the core and cladding modes, for the first time, an LPG was inscribed into such fibers using the amplitude mask technique and a KrF excimer laser. Based on this novel method, sensitive LPG-based fiber optic sensors only a few millimeters in length can be incorporated in bend-insensitive fibers for use in various monitoring applications. Moreover, by applying the described inscription method, the LPG spectrum can be influenced and tailored according to the specific demands of a particular application. PMID:29702600

  9. Long-Period Gratings in Highly Germanium-Doped, Single-Mode Optical Fibers for Sensing Applications

    Directory of Open Access Journals (Sweden)

    Sebastian Schlangen

    2018-04-01

    Full Text Available Long-period fiber gratings (LPGs are well known for their sensitivity to external influences, which make them interesting for a large number of sensing applications. For these applications, fibers with a high numerical aperture (i.e., fibers with highly germanium (Ge-doped fused silica fiber cores are more attractive since they are intrinsically photosensitive, as well as less sensitive to bend- and microbend-induced light attenuations. In this work, we introduce a novel method to inscribe LPGs into highly Ge-doped, single-mode fibers. By tapering the optical fiber, and thus, tailoring the effective indices of the core and cladding modes, for the first time, an LPG was inscribed into such fibers using the amplitude mask technique and a KrF excimer laser. Based on this novel method, sensitive LPG-based fiber optic sensors only a few millimeters in length can be incorporated in bend-insensitive fibers for use in various monitoring applications. Moreover, by applying the described inscription method, the LPG spectrum can be influenced and tailored according to the specific demands of a particular application.

  10. Tailoring light-sound interactions in a single mode fiber for the high-power transmission or sensing applications

    Science.gov (United States)

    Gulistan, Aamir; Rahman, M. M.; Ghosh, Souvik; Rahman, B. M. A.

    2018-03-01

    A full-vectorial numerically efficient Finite Element Method (FEM) based computer code is developed to study complex light-sound interactions in a single mode fiber (SMF). The SBS gain or SBS threshold in a fiber is highly related to the overlap between the optical and acoustic modes. For a typical SMF the acoustic-optic overlap strongly depends on the optical and acoustic mode profiles and it is observed that the acoustic mode is more confined in the core than the optical mode and reported overlap is around 94 % between these fundamental optical and acoustic modes. However, it is shown here that selective co-doping of Aluminum and Germanium in core reduces the acoustic index while keeping the optical index of the same value and thus results in increased acoustic- optic overlap of 99.7%. On the other hand, a design of acoustic anti-guide fiber for high-power transmission systems is also proposed, where the overlap between acoustic and optical modes is reduced. Here, we show that by keeping the optical properties same as a standard SMF and introducing a Boron doped 2nd layer in the cladding, a very low value of 2.7% overlap is achieved. Boron doping in cladding 2nd layer results in a high acoustic index and acoustic modes shifts in the cladding from the core, allowing much high power delivery through this SMF.

  11. Biologically inspired flexible quasi-single-mode random laser: an integration of Pieris canidia butterfly wing and semiconductors.

    Science.gov (United States)

    Wang, Cih-Su; Chang, Tsung-Yuan; Lin, Tai-Yuan; Chen, Yang-Fang

    2014-10-23

    Quasi-periodic structures of natural biomaterial membranes have great potentials to serve as resonance cavities to generate ecological friendly optoelectronic devices with low cost. To achieve the first attempt for the illustration of the underlying principle, the Pieris canidia butterfly wing was embedded with ZnO nanoparticles. Quite interestingly, it is found that the bio-inspired quasi-single-mode random laser can be achieved by the assistance of the skeleton of the membrane, in which ZnO nanoparticles act as emitting gain media. Such unique characteristics can be interpreted well by the Fabry-Perot resonance existing in the window-like quasi-periodic structure of butterfly wing. Due to the inherently promising flexibility of butterfly wing membrane, the laser action can still be maintained during the bending process. Our demonstrated approach not only indicates that the natural biological structures can provide effective scattering feedbacks but also pave a new avenue towards designing bio-controlled photonic devices.

  12. Dual-channel amplification in a single-mode diode laser for multi-isotope laser cooling

    International Nuclear Information System (INIS)

    Booth, James L.; Van Dongen, Janelle; Lebel, Paul; Klappauf, Bruce G.; Madison, Kirk W.

    2007-01-01

    The output from two grating-stabilized external-cavity diode lasers were injected into a single-mode diode laser. Operating at a wavelength of 780 nm, this laser produced ∼50 mW of power with two main frequency components of the same spectral characteristics of the seed lasers. The power ratio of the amplified components was freely adjustable due to gain saturation, and amplification was observed for frequency differences of the two seed lasers in the range from 73 MHz to 6.6 GHz. This system was used to realize a dual isotope magneto-optic trap (MOT) for rubidium ( 85 Rb and 87 Rb). The resulting position and cloud size of the dual isotope MOT was the same as that of the single species MOTs to within ±10 and ±20 μm, respectively. We also characterized the additional spectral components produced by four wave mixing (FWM) in the diode laser amplifier and utilized a particular FWM sideband to realize hyperfine pumping and subsequent laser trapping of 85 Rb in the absence of a 'repump' laser dedicated to hyperfine pumping

  13. Effect of thermal cycling on martensitic transformation and mechanical strengthening of stainless steels – A phase-field study

    DEFF Research Database (Denmark)

    Yeddu, Hemantha Kumar; Shaw, Brian A.; Somers, Marcel A. J.

    2017-01-01

    A 3D elastoplastic phase-field model is used to study the effect of thermal cycling on martensitic transformationas well as on mechanical strengthening of both austenite and martensite in stainless steel. The results show that with an increasing number of thermal cycles, martensite becomes more...

  14. Measurement of time series variation of thermal diffusivity of magnetic fluid under magnetic field by forced Rayleigh scattering method

    Energy Technology Data Exchange (ETDEWEB)

    Motozawa, Masaaki, E-mail: motozawa.masaaki@shizuoka.ac.jp [Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu-shi, Shizuoka 432-8561 (Japan); Muraoka, Takashi [Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu-shi, Shizuoka 432-8561 (Japan); Motosuke, Masahiro, E-mail: mot@rs.tus.ac.jp [Tokyo University of Science, 6-3-1 Niijuku, Katsushika-ku, Tokyo 125-8585 (Japan); Fukuta, Mitsuhiro, E-mail: fukuta.mitsuhiro@shizuoka.ac.jp [Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu-shi, Shizuoka 432-8561 (Japan)

    2017-04-15

    It can be expected that the thermal diffusivity of a magnetic fluid varies from time to time after applying a magnetic field because of the growth of the inner structure of a magnetic fluid such as chain-like clusters. In this study, time series variation of the thermal diffusivity of a magnetic fluid caused by applying a magnetic field was investigated experimentally. For the measurement of time series variation of thermal diffusivity, we attempted to apply the forced Rayleigh scattering method (FRSM), which has high temporal and high spatial resolution. We set up an optical system for the FRSM and measured the thermal diffusivity. A magnetic field was applied to a magnetic fluid in parallel and perpendicular to the heat flux direction, and the magnetic field intensity was 70 mT. The FRSM was successfully applied to measurement of the time series variation of the magnetic fluid from applying a magnetic field. The results show that a characteristic configuration in the time series variation of the thermal diffusivity of magnetic fluid was obtained in the case of applying a magnetic field parallel to the heat flux direction. In contrast, in the case of applying a magnetic field perpendicular to the heat flux, the thermal diffusivity of the magnetic fluid hardly changed during measurement. - Highlights: • Thermal diffusivity was measured by forced Rayleigh scattering method (FRSM). • FRSM has high temporal and high spatial resolutions for measurement. • We attempted to apply FRSM to magnetic fluid (MF). • Time series variation of thermal diffusivity of MF was successfully measured by FRSM. • Anisotropic thermal diffusivity of magnetic fluid was also successfully confirmed.

  15. On the flow, thermal field and winds along the western continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Antony, M.K.; Shenoi, S.S.C.

    drift will be in phase with the density field or in geostrophic balance. The instrusion of the Bay of 438 M.K. ANTONY and S. S. C. SHENOI Bengal water (less dense than the Arabian Sea water) into the Arabian Sea along the shelf/slope region (SARMA et... flows during May and November are in geostrophic balance or not. For this purpose we used the thermal wind equation Or_-g Op (1) Oz f Ox and substituted the observed values for the average shear (Ov/Oz) and cross-shore density gradient (Op...

  16. Large-scale magnetic fields, curvature fluctuations, and the thermal history of the Universe

    International Nuclear Information System (INIS)

    Giovannini, Massimo

    2007-01-01

    It is shown that gravitating magnetic fields affect the evolution of curvature perturbations in a way that is reminiscent of a pristine nonadiabatic pressure fluctuation. The gauge-invariant evolution of curvature perturbations is used to constrain the magnetic power spectrum. Depending on the essential features of the thermodynamic history of the Universe, the explicit derivation of the bound is modified. The theoretical uncertainty in the constraints on the magnetic energy spectrum is assessed by comparing the results obtained in the case of the conventional thermal history with the estimates stemming from less conventional (but phenomenologically allowed) post-inflationary evolutions

  17. Effective field theories for heavy Majorana neutrinos in a thermal bath

    Energy Technology Data Exchange (ETDEWEB)

    Biondini, Simone

    2016-05-06

    In the leptogenesis framework Majorana neutrinos are at the origin of the baryon asymmetry in the universe. We develop an effective field theory for non-relativistic Majorana fermions and we apply it to the case of a heavy Majorana neutrino decaying in a hot plasma of Standard Model particles, whose temperature is much smaller than the mass of the Majorana neutrino but still much larger than the electroweak scale. Moreover we compute systematically thermal corrections to the CP asymmetries in the Majorana neutrino decays.

  18. Single mode solid state distributed feedback dye laser fabricated by grey scale electron beam lithography on dye doped SU-8 resist

    DEFF Research Database (Denmark)

    Balslev, Søren; Rasmussen, Torben; Shi, Peixiong

    2005-01-01

    We demonstrate grey scale electron beam lithography on functionalized SU-8 resist for fabrication of single mode solid state dye laser devices. The resist is doped with Rhodamine 6G perchlorate and the lasers are based on a first order Bragg grating distributed feedback resonator. The lasers...

  19. Monolithic Ytterbium All-single-mode Fiber Laser with Direct Fiber-end Delivery of nJ-level Femtosecond Pulses

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry

    2008-01-01

    We demonstrate a monolithic, i.e. without any free-space coupling, all-single-mode passively modelocked Yb-fiber laser, with direct fiber-end delivery of 364−405 fs pulses of 4 nJ pulse energy using a low-loss hollow-core photonic crystal fiber compression....

  20. Effects of the gamma-ray irradiation on the optical absorption of pure silica core single-mode fibres in the visible and NIR range

    International Nuclear Information System (INIS)

    Calderon, A.; Calvo, E.; Figueroa, C.F.; Martinez-Rivero, C.; Matorras, F.; Rodrigo, T.; Sobron, M.; Vila, I.; Virto, A.L.; Arce, P.; Barcala, J.M.; Ferrando, A.; Josa, M.I.; Luque, J.M.; Molinero, A.; Navarrete, J.; Oller, J.C.; Yuste, C.

    2005-01-01

    Optical absorption induced by photon radiation was evaluated for several commercial pure silica core, single mode, optical fibres. The study was performed for three different wavelengths: 630, 670 and 785 nm. We have identified a fibre whose induced transmission loss stays below 1 dB/m after 300 kGy gamma-ray irradiation

  1. 32-core Dense SDM Unidirectional Transmission of PDM-16QAM Signals Over 1600 km Using Crosstalk-managed Single-mode Heterogeneous Multicore Transmission Line

    DEFF Research Database (Denmark)

    Mizuno, Takayuki; Shibahara, K.; Ono, Hirotaka

    2016-01-01

    We demonstrate 32-core dense space-division multiplexed (DSDM) unidirectional transmission of PDM-16QAM 20-WDM signals over 1644.8 km employing a low-crosstalk single-mode heterogeneous 32-core fiber in a partial recirculating-loop system....

  2. Investigation on seasonal variation of thermal-induced strain in flexible pavements based on field and laboratory measurements

    Directory of Open Access Journals (Sweden)

    Simita Biswas

    2016-09-01

    Full Text Available Pavement temperature variation has a large influence on the structural response of flexible pavements. Daily and seasonal temperature fluctuation causes expansion and contraction of pavement material, which then leads to the generation of thermal strain. In this study, field observation and laboratory tests were conducted to investigate seasonal variation of thermal-induced strain in flexible pavement. Field observations were conducted at the Integrated Road Research Facility (IRRF’s test road in Edmonton, Alberta, Canada, which is fully equipped with structural and environmental monitoring instruments. The main objective of the field study was to compare the variation of thermal-induced strain in warm and cold seasons. Field results indicated that thermal-induced strain is 1.4–2.0 times greater in cold seasons than in warm seasons following the same pavement temperature variations; however, strain generation rate was greater in warm seasons. Laboratory testing of asphalt slab and cylindrical samples produced comparable ratios. Moreover, field observation and laboratory testing showed a similar trend of temperature and thermal strain variations. Keywords: Thermal-induced strain, Asphalt strain gauge, Field observation, Flexible pavement, Laboratory testing, Seasonal variation

  3. Equilibrium Eulerian approach for predicting the thermal field of a dispersion of small particles

    Energy Technology Data Exchange (ETDEWEB)

    Ferry, J. [University of Illinois, Urbana-Champaign, IL (United States). Center for Simulation of Advanced Rockets; Balachandar, S. [University of Illinois, Urbana-Champaign, IL (United States). Dept. of Theoretical and Applied Mechanics

    2005-02-01

    The equilibrium Eulerian method [J. Ferry, S. Balachandar, A fast Eulerian method for disperse two-phase flow, Int. J. Multiphase Flow 27 (7) (2001) 1199-1226] provides an accurate approximation to the velocity field of sufficiently small dispersed particles in a turbulent fluid. In particular, it captures the important physics of particle response to turbulent flow, such as preferential concentration and turbophoresis. It is therefore employed as an efficient alternative to solving a PDE to determine the particle velocity field. Here we explore two possible extensions of this method to determine the particle temperature field accurately and efficiently, as functions of the underlying fluid velocity and temperature fields. Both extensions are theoretically shown to be highly accurate for asymptotically small particles. Their behavior for finite-size particles is assessed in a DNS of turbulent channel flow (Re{sub {tau}} = 150) with a passive temperature field (Pr = 1). Here it is found that although the order of accuracy of the two extensions is the same, the constant factor by which one is superior to the other can be quite large, so the less accurate extension is appropriate only in the case of a very small mechanical-to-thermal response time ratio. (Author)

  4. Post-deposition control of ferroelastic stripe domains and internal electric field by thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Feigl, L.; Iwanowska, M.; Sandu, C. S.; Setter, N. [Ceramics Laboratory, EPFL-Swiss Federal Institute of Technology, Lausanne, CH-1015 Switzerland (Switzerland); Janolin, P.-E. [Laboratoire Structures, Propriétés et Modélisation des Solides, UMR CNRS-École Centrale Paris, Grande Voie des Vignes, 92295 Châtenay-Malabry Cedex (France); Yamada, T. [Department of Materials, Physics and Energy Engineering, Nagoya University, Nagoya 464-8603 (Japan); PRESTO, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)

    2015-01-19

    The dependence of the formation of ferroelastic stripe domain patterns on the thermal history is investigated by detailed piezoresponse force microscopy and X-ray diffraction experiments after and during annealing of tensile strained tetragonal Pb(Ti,Zr)O{sub 3} epitaxial thin films on DyScO{sub 3} substrates. In particular, the ferroelastic pattern is reversibly interchanged between a cross-hatched and a stripe domain pattern if the films are cooled at different rates after annealing above the formation temperature of a-domains. Different types of 180° and non-180° patterns can be created, depending on the thermal treatment. The changes in the 180° domain structure and lattice parameters are attributed to a change of oxygen vacancy concentration, which results in a modification of the internal electric field and unit cell size, causing also a shift of T{sub C}. Thermal treatment is done on rhombohedral La:BiFeO{sub 3} thin films as well. It is observed that also in these films, appropriate heat treatment modifies the domain pattern and films with a stripe domain pattern can be created, confirming the general validity of the developed model.

  5. Demand Shifting With Thermal Mass in Large Commercial Buildings:Field Tests, Simulation and Audits

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Peng; Haves, Philip; Piette, Mary Ann; Zagreus, Leah

    2005-09-01

    The principle of pre-cooling and demand limiting is to pre-cool buildings at night or in the morning during off-peak hours, storing cooling in the building thermal mass and thereby reducing cooling loads and reducing or shedding related electrical demand during the peak periods. Cost savings are achieved by reducing on-peak energy and demand charges. The potential for utilizing building thermal mass for load shifting and peak demand reduction has been demonstrated in a number of simulation, laboratory, and field studies (Braun 1990, Ruud et al. 1990, Conniff 1991, Andresen and Brandemuehl 1992, Mahajan et al. 1993, Morris et al. 1994, Keeney and Braun 1997, Becker and Paciuk 2002, Xu et al. 2003). This technology appears to have significant potential for demand reduction if applied within an overall demand response program. The primary goal associated with this research is to develop information and tools necessary to assess the viability of and, where appropriate, implement demand response programs involving building thermal mass in buildings throughout California. The project involves evaluating the technology readiness, overall demand reduction potential, and customer acceptance for different classes of buildings. This information can be used along with estimates of the impact of the strategies on energy use to design appropriate incentives for customers.

  6. The plasma wake field excitation: Recent developments from thermal to quantum regime

    Science.gov (United States)

    Fedele, Renato; Tanjia, Fatema; de Nicola, Sergio; Jovanović, Dušan; Jovanović

    2013-12-01

    To describe the transverse nonlinear and collective self-consistent interaction of a long relativistic electron or positron beam with an unmagnetized plasma, a pair of coupled nonlinear differential equations were proposed by Fedele and Shukla in 1992 (Fedele, R. and Shukla, P. K. 1992a Phys. Rev. A 45, 4045). They were obtained within the quantum-like description provided by the thermal wave model and the theory of plasma wake field excitation. The pair of equations comprises a 2D Schrödinger-like equation for a complex wave function (whose squared modulus is proportional to beam density) and a Poisson-like equation for the plasma wake potential. The dispersion coefficient of the Schrödinger-like equation is proportional to the beam thermal emittance. More recently, Fedele-Shukla equations have been further applied to magnetized plasmas, and solutions were found in the form of nonlinear vortex states and ring solitons. They have been also applied to plasma focusing problems and extended from thermal to quantum regimes. We present here a review of the original approach, and subsequent developments.

  7. Aggregation of egg white proteins with pulsed electric fields and thermal processes.

    Science.gov (United States)

    Wu, Li; Zhao, Wei; Yang, Ruijin; Yan, Wenxu; Sun, Qianyan

    2016-08-01

    Pulsed electric field (PEF) processing is progressing towards application for liquid egg to ensure microbial safety. However, it usually causes protein aggregation, and the mechanism is still unclear. In this study, egg white protein was applied to investigate the changes in protein structure and mechanism of aggregates formation and a comparison was made with thermal treatment. Soluble protein content decreased with the increase of turbidity after both treatments. Fluorescence intensity and free sulfhydryl content were increased after being treated at 70 °C for 4 min. Less-remarkable changes of hydrophobicity were observed after PEF treatments (30 kV cm(-1) , 800 µs). Soluble and insoluble aggregates were observed by thermal treatment, and disulfide bonds were the main binding forces. The main components of insoluble aggregates formed by thermal treatment were ovotransferrin (30.58%), lysozyme (18.47%) and ovalbumin (14.20%). While only insoluble aggregates were detected during PEF processes, which consists of ovotransferrin (11.86%), lysozyme (21.11%) and ovalbumin (31.07%). Electrostatic interaction played a very important role in the aggregates formation. PEF had a minor impact on the structure of egg white protein. PEF had insignificant influence on heat-sensitive protein, indicating that PEF has potential in processing food with high biological activity and heat sensitive properties. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  8. The role of nano-particles in the field of thermal spray coating technology

    Science.gov (United States)

    Siegmann, Stephan; Leparoux, Marc; Rohr, Lukas

    2005-06-01

    Nano-particles play not only a key role in recent research fields, but also in the public discussions about health and safety in nanotechnology. Nevertheless, the worldwide activities in nano-particles research increased dramatically during the last 5 to 10 years. There are different potential routes for the future production of nano-particles at large scale. The main directions envisaged are mechanical milling, wet chemical reactions or gas phase processes. Each of the processes has its specific advantages and limitations. Mechanical milling and wet chemical reactions are typically time intensive and batch processes, whereas gas phase productions by flames or plasma can be carried out continuously. Materials of interest are mainly oxide ceramics, carbides, nitrides, and pure metals. Nano-ceramics are interesting candidates for coating technologies due to expected higher coating toughness, better thermal shock and wear resistance. Especially embedded nano-carbides and-nitrides offer homogenously distributed hard phases, which enhance coatings hardness. Thermal spraying, a nearly 100 years old and world wide established coating technology, gets new possibilities thanks to optimized, nano-sized and/or nano-structured powders. Latest coating system developments like high velocity flame spraying (HVOF), cold gas deposition or liquid suspension spraying in combination with new powder qualities may open new applications and markets. This article gives an overview on the latest activities in nano-particle research and production in special relation to thermal spray coating technology.

  9. High Performance Polymer Field-Effect Transistors Based on Thermally Crosslinked Poly(3-hexylthiophene)

    International Nuclear Information System (INIS)

    Jiang Chun-Xia; Yang Xiao-Yan; Zhao Kai; Wu Xiao-Ming; Yang Li-Ying; Cheng Xiao-Man; Yin Shou-Gen; Wei Jun

    2011-01-01

    The performance of polymer field-effect transistors is improved by thermal crosslinking ofpoly(3-hexylthiophene), using ditert butyl peroxide as the crosslinker. The device performance depends on the crosslinker concentration significantly. We obtain an optimal on/off ratio of 10 5 and the saturate field-effect mobility of 0.34cm 2 V −1 s −1 , by using a suitable ratios of ditert butyl peroxide, 0.5 wt% ofpoly(3-hexylthiophene). The microstructure images show that the crosslinked poly(3-hexylthiophene) active layers simultaneously possess appropriate crystallinity and smooth morphology. Moreover, crosslinking of poly(3-hexylthiophene) prevents the transistors from large threshold voltage shifts under ambient bias-stressing, showing an advantage in encouraging device environmental and operating stability. (cross-disciplinary physics and related areas of science and technology)

  10. Graphene-based photovoltaic cells for near-field thermal energy conversion.

    Science.gov (United States)

    Messina, Riccardo; Ben-Abdallah, Philippe

    2013-01-01

    Thermophotovoltaic devices are energy-conversion systems generating an electric current from the thermal photons radiated by a hot body. While their efficiency is limited in far field by the Schockley-Queisser limit, in near field the heat flux transferred to a photovoltaic cell can be largely enhanced because of the contribution of evanescent photons, in particular for a source supporting a surface mode. Unfortunately, in the infrared where these systems operate, the mismatch between the surface-mode frequency and the semiconductor gap reduces drastically the potential of this technology. In this paper we propose a modified thermophotovoltaic device in which the cell is covered by a graphene sheet. By discussing the transmission coefficient and the spectral properties of the flux, we show that both the cell efficiency and the produced current can be enhanced, paving the way to promising developments for the production of electricity from waste heat.

  11. Thermal field emission observation of single-crystal LaB6

    International Nuclear Information System (INIS)

    Nagata, H.; Harada, K.; Shimizu, R.

    1990-01-01

    TFE (thermal field emission) properties of LaB 6 left-angle 100 right-angle and left-angle 310 right-angle single crystals were investigated by emission pattern observation. It was found that field evaporation with the tip temperature held at ∼1500 degree C is very useful to get a clean pattern of fourfold symmetry. Each of four bright spots in the clean pattern was presumed to correspond to left-angle 310 right-angle emission. It is proposed, as the most appropriate operating condition, to use the left-angle 310 right-angle LaB 6 tip at a temperature ∼1000 degree C in vacuum of 10 -9 Torr region, promising a new TF emitter of high brightness and stability for practical use

  12. Magnetic Thermometer: Thermal effect on the Agglomeration of Magnetic Nanoparticles by Magnetic field

    Science.gov (United States)

    Jin, Daeseong; Kim, Hackjin

    2018-03-01

    We have investigated the agglomeration of magnetite nanoparticles in the aqueous solution under magnetic field by measuring temporal change of magnetic weight. The magnetic weight corresponds to the force due to the magnetization of magnetic materials. Superparamagnetic magnetite nanoparticles are synthesized and used in this work. When the aqueous solution of magnetite nanoparticle is placed under magnetic field, the magnetic weight of the sample jumps instantaneously by Neel and Brown mechanisms and thereafter increases steadily following a stretched exponential function as the nanoparticles agglomerate, which results from the distribution of energy barriers involved in the dynamics. Thermal motions of nanoparticles in the agglomerate perturb the ordered structure of the agglomerate to reduce the magnetic weight. Fluctuation of the structural order of the agglomerate by temperature change is much faster than the formation of agglomerate and explained well with the Boltzmann distribution, which suggests that the magnetic weight of the agglomerate works as a magnetic thermometer.

  13. Effect of ballooning modes on thermal transport and magnetic field diffusion in the solar corona

    International Nuclear Information System (INIS)

    Strauss, H.R.

    1989-01-01

    Presently favored mechanisms of coronal heating: current sheet dissipation and Alfven wave resonant heating: deposit heat in thin layers. Classical thermal conduction cannot explain how heat is transported across the magnetic field. If heating occurs in thin layers, large pressure gradients can be created, which can give rise to ballooning modes. These instabilities are caused by the pressure gradient and the curvature of the magnetic field, and are stabilized by magnetic tension. The modes are broad band in wavelength and should produce turbulence. A mixing length expression for the turbulent heat transport shows that it is more than adequate to rapidly convect heat into much broader layers. Furthermore, the turbulent resistivity implies that heating occurs over most of the width of these broadened layers. The broadening also implies that much shorter time scales are required for heating. The β values in the corona suggest that 1--10 turbulent layers are formed in typical loop or arch structures. copyright American Geophysical Union 1989

  14. Geological, Geophysical, And Thermal Characteristics Of The Salton Sea Geothermal Field, California

    Energy Technology Data Exchange (ETDEWEB)

    Younker, L.W.; Kasameyer, P. W.; Tewhey, J. D.

    1981-01-01

    The Salton Sea Geothermal Field is the largest water-dominated geothermal field in the Salton Trough in Southern California. Within the trough, local zones of extension among active right-stepping right-lateral strike-slip faults allow mantle-derived magmas to intrude the sedimentary sequence. The intrusions serves as heat sources to drive hydrothermal systems. We can characterize the field in detail because we have an extensive geological and geophysical data base. The sediments are relatively undeformed and can be divided into three categories as a function of depth: (1) low-permeability cap rock, (2) upper reservoir rocks consisting of sandstones, siltstones, and shales that were subject to minor alterations, and (3) lower reservoir rocks that were extensively altered. Because of the alteration, intergranular porosity and permeability are reduced with depth. permeability is enhanced by renewable fractures, i.e., fractures that can be reactivated by faulting or natural hydraulic fracturing subsequent to being sealed by mineral deposition. In the central portion of the field, temperature gradients are high near the surface and lower below 700 m. Surface gradients in this elliptically shaped region are fairly constant and define a thermal cap, which does not necessarily correspond to the lithologic cap. At the margin of the field, a narrow transition region, with a low near-surface gradient and an increasing gradient at greater depths, separates the high temperature resource from areas of normal regional gradient. Geophysical and geochemical evidence suggest that vertical convective motion in the reservoir beneath the thermal cap is confined to small units, and small-scale convection is superimposed on large-scale lateral flow of pore fluid. Interpretation of magnetic, resistivity, and gravity anomalies help to establish the relationship between the inferred heat source, the hydrothermal system, and the observed alteration patterns. A simple hydrothermal model is

  15. Characterization of Hydrologic and Thermal Properties at Brady Geothermal Field, NV

    Science.gov (United States)

    Patterson, J.; Cardiff, M. A.; Lim, D.; Coleman, T.; Wang, H. F.; Feigl, K. L.

    2017-12-01

    Understanding and predicting the temperature evolution of geothermal reservoirs is a primary focus for geothermal power plant operators ensuring continued financial sustainability of the resource. Characterization of reservoir properties - such as thermal diffusivity and hydraulic conductivity - facilitates modeling efforts to develop a better understanding of temperature evolution. As part of the integrated "PoroTomo" experiment, borehole pressure measurements were collected in three monitoring wells of various depths under varying operational conditions at the Brady Geothermal Field near Reno, NV. During normal operational conditions, a vertical profile of borehole temperature to 330 m depth was collected using distributed temperature sensing (DTS) for a period of 5 days. Borehole pressure data indicates 2D flow and shows rapid responses to changes in pumping /injection rates, likely indicating fault-dominated flow. The temperature data show that borehole temperature recovery following cold water slug injection is variable with depth. Late time vertical temperature profiles show the borehole following a shallow geotherm to a depth of approximately 275 meters, below which the temperature declines until a depth of approximately 320 meters, with a stable zone of cold water forming below this, possibly indicating production-related thermal drawdown. A validated heat transfer model is used in conjunction with the temperature data to determine depth-dependent reservoir thermal properties. Hydraulic reservoir properties are determined through inversion of the collected pressure data using MODFLOW. These estimated thermal and hydraulic properties are synthesized with existing structural and stratigraphic datasets at Brady. The work presented herein was funded in part by the Office of Energy Efficiency and Renewable Energy (EERE), U.S. Department of Energy, under Award Number DE-EE0006760.

  16. 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.

  17. Study of equivalent retention among different polymer-solvent systems in thermal field-flow fractionation

    International Nuclear Information System (INIS)

    Kim, Won Suk; Park, Young Hun; Lee, Dai Woon; Moon, Myeong Hee; Yu, Euy Kyung

    1998-01-01

    An equivalent retention has been experimentally observed in thermal field-flow fractionation (ThFF) for different polymer-solvent systems. It is shown that iso-retention between two sets of polymer-solvent systems can be obtained by adjusting the temperature difference (ΔT) according to the difference in the ration of ordinary diffusion coefficient to thermal diffusion coefficient. This method uses a compensation of field strength (ΔT) in ThFFF at a fixed condition of cold wall temperature. It is applied for the calculation of molecular weight of polymers based on a calibration run of different standards obtained at an adjusted ΔT. The polymer standards used in this study are polystyrene (PS), polymethylmethacrylate (PMMA), and polytetrahydrofuran (PTHF). Three carrier solvents, tetrahydrofuran (THF), methylethylketone (MEK) and ethylacetate (ETAc) were employed. Though the accuracy in the calculation of molecular weight is dependent on the difference in the slope of log λ vs. log M which is related to Mark-Houwink constant a, it shows reasonable agreement within about 6% of relative error in molecular weight calculation for the polymer-solvent systems having similar a value

  18. Analysis of near-field thermal and psychometric waste package environment using ventilation

    International Nuclear Information System (INIS)

    Danko, G.

    1995-03-01

    The ultimate objective of the Civilian Radioactive Waste Management System (CRWMS) Program is to safely emplace and isolate the nations' spent nuclear fuel (SNF) and radioactive wastes in a geologic repository. Radioactive waste emplaced in a geologic repository will generate heat, increasing the temperature in the repository. The magnitude of this temperature increase depends upon (1) the heat source, i.e. the thermal loading of the repository, and (2) the geologic and engineered heat transport characteristics of the repository. Thermal management techniques currently under investigation include ventilation of the emplacement drifts during the preclosure period which could last as long as 100 years. Understanding the amount of heat and moisture removed from the emplacement drifts and near-field rock by ventilation, are important in determining performance of the engineered barrier system (EBS), as well as the corrosive environment of the waste packages, and the interaction of the EBS with the near-field host rock. Since radionuclide releases and repository system performance are significantly affected by the corrosion rate related to the psychometric environment, it is necessary to predict the amount of heat and moisture that are removed from the repository horizon using a realistic model for a wide range of thermal loading. This can be realized by coupling the hydrothermal model of the rock mass to a ventilation/climate model which includes the heat and moisture transport on the rock-air interface and the dilution of water vapor in the drift. This paper deals with the development of the coupled model concept, and determination of the boundary conditions for the calculations

  19. The alanine detector in BNCT dosimetry: dose response in thermal and epithermal neutron fields.

    Science.gov (United States)

    Schmitz, T; Bassler, N; Blaickner, M; Ziegner, M; Hsiao, M C; Liu, Y H; Koivunoro, H; Auterinen, I; Serén, T; Kotiluoto, P; Palmans, H; Sharpe, P; Langguth, P; Hampel, G

    2015-01-01

    The response of alanine solid state dosimeters to ionizing radiation strongly depends on particle type and energy. Due to nuclear interactions, neutron fields usually also consist of secondary particles such as photons and protons of diverse energies. Various experiments have been carried out in three different neutron beams to explore the alanine dose response behavior and to validate model predictions. Additionally, application in medical neutron fields for boron neutron capture therapy is discussed. Alanine detectors have been irradiated in the thermal neutron field of the research reactor TRIGA Mainz, Germany, in five experimental conditions, generating different secondary particle spectra. Further irradiations have been made in the epithermal neutron beams at the research reactors FiR 1 in Helsinki, Finland, and Tsing Hua open pool reactor in HsinChu, Taiwan ROC. Readout has been performed with electron spin resonance spectrometry with reference to an absorbed dose standard in a (60)Co gamma ray beam. Absorbed doses and dose components have been calculated using the Monte Carlo codes fluka and mcnp. The relative effectiveness (RE), linking absorbed dose and detector response, has been calculated using the Hansen & Olsen alanine response model. The measured dose response of the alanine detector in the different experiments has been evaluated and compared to model predictions. Therefore, a relative effectiveness has been calculated for each dose component, accounting for its dependence on particle type and energy. Agreement within 5% between model and measurement has been achieved for most irradiated detectors. Significant differences have been observed in response behavior between thermal and epithermal neutron fields, especially regarding dose composition and depth dose curves. The calculated dose components could be verified with the experimental results in the different primary and secondary particle fields. The alanine detector can be used without

  20. Feasibility study on using imaging plates to estimate thermal neutron fluence in neutron-gamma mixed fields

    International Nuclear Information System (INIS)

    Fujibuchi, T.; Tanabe, Y.; Sakae, T.; Terunuma, T.; Isobe, T.; Kawamura, H.; Yasuoka, K.; Matsumoto, T.; Harano, H.; Nishiyama, J.; Masuda, A.; Nohtomi, A.

    2011-01-01

    In current radiotherapy, neutrons are produced in a photonuclear reaction when incident photon energy is higher than the threshold. In the present study, a method of discriminating the neutron component was investigated using an imaging plate (IP) in the neutron-gamma-ray mixed field. Two types of IP were used: a conventional IP for beta- and gamma rays, and an IP doped with Gd for detecting neutrons. IPs were irradiated in the mixed field, and the photo-stimulated luminescence (PSL) intensity of the thermal neutron component was discriminated using an expression proposed herein. The PSL intensity of the thermal neutron component was proportional to thermal neutron fluence. When additional irradiation of photons was added to constant neutron irradiation, the PSL intensity of the thermal neutron component was not affected. The uncertainty of PSL intensities was approximately 11.4 %. This method provides a simple and effective means of discriminating the neutron component in a mixed field. (authors)

  1. A self-consistent model of a thermally balanced quiescent prominence in magnetostatic equilibrium in a uniform gravitational field

    International Nuclear Information System (INIS)

    Lerche, I.; Low, B.C.

    1977-01-01

    A theoretical model of quiescent prominences in the form of an infinite vertical sheet is presented. Self-consistent solutions are obtained by integrating simultaneously the set of nonlinear equations of magnetostatic equilibrium and thermal balance. The basic features of the models are: (1) The prominence matter is confined to a sheet and supported against gravity by a bowed magnetic field. (2) The thermal flux is channelled along magnetic field lines. (3) The thermal flux is everywhere balanced by Low's (1975) hypothetical heat sink which is proportional to the local density. (4) A constant component of the magnetic field along the length of the prominence shields the cool plasma from the hot surrounding. It is assumed that the prominence plasma emits more radiation than it absorbes from the radiation fields of the photosphere, chromosphere and corona, and the above hypothetical heat sink is interpreted to represent the amount of radiative loss that must be balanced by a nonradiative energy input. Using a central density and temperature of 10 11 particles cm -3 and 5000 K respectively, a magnetic field strength between 2 to 10 gauss and a thermal conductivity that varies linearly with temperature, the physical properties implied by the model are discussed. The analytic treatment can also be carried out for a class of more complex thermal conductivities. These models provide a useful starting point for investigating the combined requirements of magnetostatic equilibrium and thermal balance in the quiescent prominence. (Auth.)

  2. Super-Gaussian transport theory and the field-generating thermal instability in laser–plasmas

    International Nuclear Information System (INIS)

    Bissell, J J; Ridgers, C P; Kingham, R J

    2013-01-01

    Inverse bremsstrahlung (IB) heating is known to distort the electron distribution function in laser–plasmas from a Gaussian towards a super-Gaussian, thereby modifying the equations of classical transport theory (Ridgers et al 2008 Phys. Plasmas 15 092311). Here we explore these modified equations, demonstrating that super-Gaussian effects both suppress traditional transport processes, while simultaneously introducing new effects, such as isothermal (anomalous Nernst) magnetic field advection up gradients in the electron number density n e , which we associate with a novel heat-flow q n ∝∇n e . Suppression of classical phenomena is shown to be most pronounced in the limit of low Hall-parameter χ, in which case the Nernst effect is reduced by a factor of five, the ∇T e × ∇n e field generation mechanism by ∼30% (where T e is the electron temperature), and the diffusive and Righi–Leduc heat-flows by ∼80 and ∼90% respectively. The new isothermal field advection phenomenon and associated density-gradient driven heat-flux q n are checked against kinetic simulation using the Vlasov–Fokker–Planck code impact, and interpreted in relation to the underlying super-Gaussian distribution through simplified kinetic analysis. Given such strong inhibition of transport at low χ, we consider the impact of IB on the seeding and evolution of magnetic fields (in otherwise un-magnetized conditions) by examining the well-known field-generating thermal instability in the light of super-Gaussian transport theory (Tidman and Shanny 1974 Phys. Fluids 12 1207). Estimates based on conditions in an inertial confinement fusion (ICF) hohlraum suggest that super-Gaussian effects can reduce the growth-rate of the instability by ≳80%. This result may be important for ICF experiments, since by increasing the strength of IB heating it would appear possible to inhibit the spontaneous generation of large magnetic fields. (paper)

  3. Super-Gaussian transport theory and the field-generating thermal instability in laser-plasmas

    Science.gov (United States)

    Bissell, J. J.; Ridgers, C. P.; Kingham, R. J.

    2013-02-01

    Inverse bremsstrahlung (IB) heating is known to distort the electron distribution function in laser-plasmas from a Gaussian towards a super-Gaussian, thereby modifying the equations of classical transport theory (Ridgers et al 2008 Phys. Plasmas 15 092311). Here we explore these modified equations, demonstrating that super-Gaussian effects both suppress traditional transport processes, while simultaneously introducing new effects, such as isothermal (anomalous Nernst) magnetic field advection up gradients in the electron number density ne, which we associate with a novel heat-flow qn∝∇ne. Suppression of classical phenomena is shown to be most pronounced in the limit of low Hall-parameter χ, in which case the Nernst effect is reduced by a factor of five, the ∇Te × ∇ne field generation mechanism by ˜30% (where Te is the electron temperature), and the diffusive and Righi-Leduc heat-flows by ˜80 and ˜90% respectively. The new isothermal field advection phenomenon and associated density-gradient driven heat-flux qn are checked against kinetic simulation using the Vlasov-Fokker-Planck code impact, and interpreted in relation to the underlying super-Gaussian distribution through simplified kinetic analysis. Given such strong inhibition of transport at low χ, we consider the impact of IB on the seeding and evolution of magnetic fields (in otherwise un-magnetized conditions) by examining the well-known field-generating thermal instability in the light of super-Gaussian transport theory (Tidman and Shanny 1974 Phys. Fluids 12 1207). Estimates based on conditions in an inertial confinement fusion (ICF) hohlraum suggest that super-Gaussian effects can reduce the growth-rate of the instability by ≳80%. This result may be important for ICF experiments, since by increasing the strength of IB heating it would appear possible to inhibit the spontaneous generation of large magnetic fields.

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

    International Nuclear Information System (INIS)

    Tachinami, C.; Ida, S.; Senshu, H.

    2011-01-01

    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 (M p ), independent of the initial temperature gap at the CMB (ΔT CMB ), but beyond the critical value M c,p (∼O(1) M + ) it abruptly declines from the mantle viscosity enhancement due to the pressure effect. We derived M c,p as a function of ΔT CMB and a rheological parameter (activation volume, V*). Thus, the magnetic field lifetime of super-Earths with M p >M p,c sensitively depends on ΔT CMB , 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. Numerical and experimental investigations of coupled electromagnetic and thermal fields in superconducting accelerator magnets

    International Nuclear Information System (INIS)

    Mierau, Anna

    2013-01-01

    The new international facility for antiproton and ion research FAIR will be built in Darmstadt (Germany). The existing accelerator facility of GSI Helmholtzzentrum for Heavy Ion Research will serve as a pre-accelerator for the new facility. FAIR will provide high-energy antiproton and ion beams with unprecedented intensity and quality for fundamental research of states of matter and the evolution of the universe. The central component of FAIR's accelerator and storage rings complex is a double-ring accelerator consisting of two heavy ion synchrotrons SIS100 and SIS300. The SIS100 is the primary accelerator of FAIR. The desired beam properties of SIS100 require a design of the machine much more challenging than the conventional design of existing proton and ion synchrotrons. The key technical components of each synchrotron are the special electromagnets, which allow guiding the charged particles on their orbits in the synchrotron during the acceleration processes. For a stable operation of the SIS100's the magnets have to produce extremely homogeneous magnetic fields. Furthermore, the SIS100 high-intensity ion beam modes, for example with U 28+ ions, require an ultra-high vacuum in the beam pipe of the synchrotron, which can be generated effectively only at low temperatures below 15 K. Due to the field quality requirements for the magnets, the properties of the dynamic vacuum in the beam pipe but also in order to minimise future operating costs, fast ramped superconducting magnets will be used to guide the beam in SIS100. These magnets have been developed at GSI within the framework of the FAIR project. Developing a balanced design of a superconducting accelerator magnet requires a sound understanding of the interaction between its thermal and electromagnetic fields. Of special importance in this case are the magnetic field properties such as the homogeneity of the static magnetic field in the aperture of the magnet, and the dynamic heat losses of the whole magnet

  6. ESR-dosimetry in thermal and epithermal neutron fields for application in boron neutron capture therapy

    Energy Technology Data Exchange (ETDEWEB)

    Schmitz, Tobias

    2016-01-22

    Dosimetry is essential for every form of radiotherapy. In Boron Neutron Capture Therapy (BNCT) mixed neutron and gamma fields have to be considered. Dose is deposited in different neutron interactions with elements in the penetrated tissue and by gamma particles, which are always part of a neutron field. The therapeutic dose in BNCT is deposited by densely ionising particles, originating from the fragmentation of the isotope boron-10 after capture of a thermal neutron. Despite being investigated for decades, dosimetry in neutron beams or fields for BNCT remains complex, due to the variety in type and energy of the secondary particles. Today usually ionisation chambers combined with metal foils are used. The applied techniques require extensive effort and are time consuming, while the resulting uncertainties remain high. Consequently, the investigation of more effective techniques or alternative dosimeters is an important field of research. In this work the possibilities of ESR-dosimeters in those fields have been investigated. Certain materials, such as alanine, generate stable radicals upon irradiation. Using Electron Spin Resonance (ESR) spectrometry the amount of radicals, which is proportional to absorbed dose, can be quantified. Different ESR detector materials have been irradiated in the thermal neutron field of the research reactor TRIGA research reactor in Mainz, Germany, with five setups, generating different secondary particle spectra. Further irradiations have been conducted in two epithermal neutron beams. The detector response, however, strongly depends on the dose depositing particle type and energy. It is hence necessary to accompany measurements by computational modelling and simulation. In this work the Monte Carlo code FLUKA was used to calculate absorbed doses and dose components. The relative effectiveness (RE), linking absorbed dose and detector response, has been calculated using amorphous track models. For the simulation, detailed models of

  7. Thermal fluctuations in pinned elastic systems: field theory of rare events and droplets

    International Nuclear Information System (INIS)

    Balents, Leon; Le Doussal, Pierre

    2005-01-01

    Using the functional renormalization group (FRG) we study the thermal fluctuations of elastic objects (displacement field u, internal dimension d) pinned by a random potential at low temperature T, as prototypes for glasses. A challenge is how the field theory can describe both typical (minimum energy T = 0) configurations, as well as thermal averages which, at any non-zero T as in the phenomenological droplet picture, are dominated by rare degeneracies between low lying minima. We show that this occurs through an essentially non-perturbative thermal boundary layer (TBL) in the (running) effective action Γ [u] at T > 0 for which we find a consistent scaling ansatz to all orders. The TBL describes how temperature smoothes the singularities of the T = 0 theory and contains the physics of rare thermal excitations (droplets). The formal structure of this TBL, which involves all cumulants of the coarse grained disorder, is first explored around d = 4 using a one-loop Wilson RG. Next, a more systematic exact RG (ERG) method is employed, and first tested on d = 0 models where it can be pushed quite far. There we obtain precise relations between TBL quantities and droplet probabilities (those are constrained by exact identities which are then checked against recent exact results). Our analysis is then extended to higher d, where we illustrate how the TBL scaling remains consistent to all orders in the ERG and how droplet picture results can be retrieved. Since correlations are determined deep in the TBL (by derivatives of Γ [u] at u = 0), it remains to be understood (in any d) how they can be retrieved (as u = 0 + limits in the non-analytic T = 0 effective action), i.e., how to recover a T = 0 critical theory. This formidable 'matching problem' is solved in detail for d = 0, N = 1 by studying the (partial) TBL structure of higher cumulants when points are brought together. We thereby obtain the β-function at T = 0, all ambiguities removed, displayed here up to four

  8. Effect of Thermal Fields on the Structure of Corrosion-Resistant Steels Under Different Modes of Laser Treatment

    Science.gov (United States)

    Tarasova, T. V.; Gusarov, A. V.; Protasov, K. E.; Filatova, A. A.

    2017-11-01

    The influence of temperature fields on the structure and properties of corrosion-resistant chromium steels under different modes of laser treatment is investigated. A model of heat transfer under laser impact on target is used to plot thermal fields and cycles and cooling rates. It is shown that the model used for computing thermal fields gives tentative geometric sizes of the fusion zones under laser treatment and selective laser fusion. The cooling rate is shown to have decisive influence on the structure of corrosion-resistant steels after laser treatment with surface fusion in devices for pulsed, continuous, and selective laser melting.

  9. An investigation into thermal comfort and residential thermal environment in an intertropical sub-Saharan Africa region: Field study report during the Harmattan season in Cameroon

    International Nuclear Information System (INIS)

    Djongyang, Noel; Tchinda, Rene

    2010-01-01

    Investigations on thermal comfort have attracted authors for years throughout the world and the most important findings are now the basis of international thermal comfort standards. There is little information available concerning occupant comfort and residential thermal environment in the intertropical sub-Saharan Africa. Thus the purpose for this study is to conduct a field study on comfort and residential thermal environments in a typical intertropical climatic region. A field survey has been conducted during the Harmattan season in two cities from the two climatic regions of Cameroon concerned by that wind. Specific study objectives were to evaluate and characterize some thermal perceptions of occupants in their residence, compare observed and predicted percent of dissatisfied, and discern differences between the study area and other climate zones where similar studies have been performed. It was found that the thermoneutral temperatures in both climatic regions range from 24.69 deg. C to 27.32 deg. C and, in traditional living room, it differs from that of modern living room with approximately 1 deg. C.

  10. Evaluation of using ferrofluid as an interface material for a field-reversible thermal connector

    Science.gov (United States)

    Yousif, Ahmed S.

    The electrical functionality of an avionics chassis is limited due to heat dissipation limits. The limits arise due to the fact that components in an avionic computer boxes are packed very compactly, with the components mounted onto plug-in cards, and the harsh environment experienced by the chassis limits how heat can be dissipated from the cards. Convective and radiative heat transfer to the ambient are generally not possible. Therefore it is necessary to have heat transferred from the components conducted to the edge of the plug-in cards. The heat then needs to conduct from the card edge to a cold block that not only holds the card in place, but also removes the generated heat by some heat transfer fluid that is circulated through the cold block. The interface between the plug-in card and the cold block typically has a high thermal resistance since it is necessary for the card to have the capability to be re-workable, meaning that the card can be removed and then returned to the chassis. Reducing the thermal resistance of the interface is the objective of the current study and the topic of this thesis. The current design uses a pressure interface between the card and cold block. The contact pressure is increased through the addition of a wedgelock, which is a field-reversible mechanical connector. To use a wedgelock, the cold block has channels milled on the surface with widths that are larger than the thickness of the plug-in card and the un-expanded wedgelock. The card edge is placed in the channel and placed against one of the channel walls. A wedgelock is then placed between the card and the other channel wall. The wedgelock is then expanded by using either a screw or a lever. As the wedgelock expands it fills in the remaining channel gap and bears against the other face of the plug-in card. The majority of heat generated by the components on the plug-in card is forced to conduct from the card into the wall of the cold block, effectively a single sided, dry

  11. Thermal and electrical joint test for the helical field coils in the Advanced Toroidal Facility

    International Nuclear Information System (INIS)

    Brown, R.L.; Johnson, R.L.

    1985-01-01

    Initial feasibility studies of a number of configurations for the Advanced Toroidal Facility (ATF) resulted in the selection of a resistive copper continuous-coil torsatron as the optimum device considering the physics program, cost, and schedule. Further conceptual design work was directed toward optimization of this configuration and, if possible, a shorter schedule. It soon became obvious that in order to shorten the schedule, a number of design and fabrication activities should proceed in parallel. This was most critical for the vacuum vessel and the helical field (HF) coils. If the HF coils were wound in place on a completed vacuum vessel, the overall schedule would be significantly (greater than or equal to12 months) longer. The approach of parallel scheduel paths requires that the HF coils be segmented into parts of less than or equal to180 0 of poloidal angle and that joints be made on a turn-by-turn basis when the segments are installed. It was obvious from the outset that the compact and complex geometry of the joint design presented a special challenge in the areas of reliability, assembly, maintenance, disassembly, and cost. Also, electrical, thermal, and force excursions are significant for these joints. A number of soldered, welded, brazed, electroplated, and bolted joints were evaluated. The evaluations examined fabrication feasibility and complexity, thermal-electrical performance at approximately two-thirds of the steady-state design conditions, and installation and assembly processes. Results of the thermal-electrical tests were analyzed and extrapolated to predict performance at peak design parameters. The final selection was a lap-type joint clamped with insulated bolts that pass through the winding packing. 3 refs., 4 figs

  12. Probing thermal evanescent waves with a scattering-type near-field microscope

    International Nuclear Information System (INIS)

    Kajihara, Y; Kosaka, K; Komiyama, S

    2011-01-01

    Long wavelength infrared (LWIR) waves contain many important spectra of matters like molecular motions. Thus, probing spontaneous LWIR radiation without external illumination would reveal detailed mesoscopic phenomena that cannot be probed by any other measurement methods. Here we developed a scattering-type scanning near-field optical microscope (s-SNOM) and demonstrated passive near-field microscopy at 14.5 µm wavelength. Our s-SNOM consists of an atomic force microscope and a confocal microscope equipped with a highly sensitive LWIR detector, called a charge-sensitive infrared phototransistor (CSIP). In our s-SNOM, photons scattered by a tungsten probe are collected by an objective of the confocal LWIR microscope and are finally detected by the CSIP. To suppress the far-field background, we vertically modulated the probe and demodulated the signal with a lock-in amplifier. With the s-SNOM, a clear passive image of 3 µm pitch Au/SiC gratings was successfully obtained and the spatial resolution was estimated to be 60 nm (λ/240). The radiation from Au and GaAs was suggested to be due to thermally excited charge/current fluctuations and surface phonons, respectively. This s-SNOM has the potential to observe mesoscopic phenomena such as molecular motions, biomolecular protein interactions and semiconductor conditions in the future

  13. Ground-based infrared surveys: imaging the thermal fields at volcanoes and revealing the controlling parameters.

    Science.gov (United States)

    Pantaleo, Michele; Walter, Thomas

    2013-04-01

    Temperature monitoring is a widespread procedure in the frame of volcano hazard monitoring. Indeed temperature changes are expected to reflect changes in volcanic activity. We propose a new approach, within the thermal monitoring, which is meant to shed light on the parameters controlling the fluid pathways and the fumarole sites by using infrared measurements. Ground-based infrared cameras allow one to remotely image the spatial distribution, geometric pattern and amplitude of fumarole fields on volcanoes at metre to centimetre resolution. Infrared mosaics and time series are generated and interpreted, by integrating geological field observations and modeling, to define the setting of the volcanic degassing system at shallow level. We present results for different volcano morphologies and show that lithology, structures and topography control the appearance of fumarole field by the creation of permeability contrasts. We also show that the relative importance of those parameters is site-dependent. Deciphering the setting of the degassing system is essential for hazard assessment studies because it would improve our understanding on how the system responds to endogenous or exogenous modification.

  14. Thermal effects in quantized fields in the example of the Gross-Neveu model

    International Nuclear Information System (INIS)

    Englert, B.G.

    1981-01-01

    The Gross-Nerau model is applied to discuss thermal effects in quantized fields in an exemplary way. For this the effective potential for arbitrary temperature is calculated in one-loop approximation, i.e. in lowest order of the 1/N-expansion. It is proved to be convenient to regulate the model dimensionally and to renormalize by subtraction in the momentum dimensionally and to renormalize by subtraction in the momentum space. From the effective potential the temperature dependence of the fermion mass generated by dynamical symmetry breaking is obtained. This result can be reproduced by a manifestly selfconsistent calculation which leads in a natural way to the tadpole equation. The calculation of temperature dependent elastic scattering cross sections rounds the one-loop calculations of and gives hints, in which direction the experimental search for thermal effects could possible be successful. Furthermore the tadpole equation is evaluation in two-loop approximation. Thereby it is shown that only a self-consistent renormalization yields evaluable results while in a perturbative renormalization the dimensional transmutation cannot be performed. Indeed no real improvements of the one-loop results are obtained which is due to the fact that not all contributions of the next 1/N-order are taken into account. (orig.) [de

  15. Theory and calculation of water distribution in bentonite in a thermal field

    International Nuclear Information System (INIS)

    Carnahan, C.L.

    1988-09-01

    Highly compacted bentonite is under consideration for use as a buffer material in geological repositories for high-level radioactive wastes. To assess the suitability of bentonite for this use, it is necessary to be able to predict the rate and spatial extent of water uptake and water distribution in highly compacted bentonite in the presence of thermal gradients. The ''Buffer Mass Test'' (BMT) was conducted by workers in Sweden as part of the Stripa Project. The BMT measured uptake and spatial distributions of water infiltrating annuli of compacted MX-80 sodium bentonite heated from within and surrounded by granite rock; the measurements provided a body of data very valuable for comparison to results of theoretical calculations. Results of experiments on adsorption of water by highly compacted MX-80 bentonite have been reported by workers in Switzerland. The experiments included measurements of heats of immersion and adsorption-desorption isotherms. These measurements provide the basis for prediction of water vapor pressures in equilibrium with bentonite having specified adsorbed water contents at various temperatures. The present work offers a phenomenological description of the processes influencing movement of water in compacted bentonite in the presence of a variable thermal field. The theory is applied to the bentonite buffer-water system in an assumed steady state of heat and mass transport, using critical data derived from the experimental work done in Switzerland. Results of the theory are compared to distributions of absorbed water in buffers observed in the Swedish BMT experiments. 9 refs., 2 figs

  16. Thermal fluctuation levels of magnetic and electric fields in unmagnetized plasma: The rigorous relativistic kinetic theory

    International Nuclear Information System (INIS)

    Yoon, P. H.; Schlickeiser, R.; Kolberg, U.

    2014-01-01

    Any fully ionized collisionless plasma with finite random particle velocities contains electric and magnetic field fluctuations. The fluctuations can be of three different types: weakly damped, weakly propagating, or aperiodic. The kinetics of these fluctuations in general unmagnetized plasmas, governed by the competition of spontaneous emission, absorption, and stimulated emission processes, is investigated, extending the well-known results for weakly damped fluctuations. The generalized Kirchhoff radiation law for both collective and noncollective fluctuations is derived, which in stationary plasmas provides the equilibrium energy densities of electromagnetic fluctuations by the ratio of the respective spontaneous emission coefficient and the true absorption coefficient. As an illustrative example, the equilibrium energy densities of aperiodic transverse collective electric and magnetic fluctuations in an isotropic thermal electron-proton plasmas of density n e are calculated as |δB|=√((δB) 2 )=2.8(n e m e c 2 ) 1/2 g 1/2 β e 7/4 and |δE|=√((δE) 2 )=3.2(n e m e c 2 ) 1/2 g 1/3 β e 2 , where g and β e denote the plasma parameter and the thermal electron velocity in units of the speed of light, respectively. For densities and temperatures of the reionized early intergalactic medium, |δB|=6·10 −18 G and |δE|=2·10 −16 G result

  17. Phase-field simulations of pore migration and morphology change in thermal gradients

    Energy Technology Data Exchange (ETDEWEB)

    Vance, Ian W.; Millett, Paul C., E-mail: pmillett@uark.edu

    2017-07-15

    Here we present a phase-field simulation model that captures the thermal-gradient-driven migration of pores in oxide fuel associated with fuel restructuring. The model utilizes a Cahn-Hilliard equation supplemented with an advection term to describe the vapor transport of fuel material through the pore interior due to gradients in vapor pressure. Simulations demonstrate that the model not only predicts pore migration towards the centerline of the fuel, but also a concurrent change in pore shape during migration from an initially isotropic morphology to either a lenticular morphology or a prolate morphology depending on the vapor transport conditions. This model is a necessary first step to conducting accurate simulations of the microscopic changes that occur during the complicated process of oxide fuel restructuring.

  18. Phase field modelling of dynamic thermal fracture in the context of irradiation damage

    CERN Document Server

    Schlüter, Alexander; Müller, Ralf; Tomut, Marilena; Trautmann , Christina; Weick, Helmut; Plate, Carolin

    2015-01-01

    This work presents a continuum mechanics approach to model fracturing processes in brittle materials that are subjected to rapidly applied high-temperature gradients. Such a type of loading typically occurs when a solid is exposed to an intense high-energy particle beam that deposits a large amount of energy into a small sample volume. Given the rapid energy deposition leading to a fast temperature increase, dynamic effects have to be considered. Our existing phase field model for dynamic fracture is thus extended in a way that allows modelling of thermally induced fracture. A finite element scheme is employed to solve the governing partial differential equations numerically. Finally, the functionality of our model is illustrated by two examples.

  19. Dynamics of entropic uncertainty for atoms immersed in thermal fluctuating massless scalar field

    Science.gov (United States)

    Huang, Zhiming

    2018-04-01

    In this article, the dynamics of quantum memory-assisted entropic uncertainty relation for two atoms immersed in a thermal bath of fluctuating massless scalar field is investigated. The master equation that governs the system evolution process is derived. It is found that the mixedness is closely associated with entropic uncertainty. For equilibrium state, the tightness of uncertainty vanishes. For the initial maximum entangled state, the tightness of uncertainty undergoes a slight increase and then declines to zero with evolution time. It is found that temperature can increase the uncertainty, but two-atom separation does not always increase the uncertainty. The uncertainty evolves to different relatively stable values for different temperatures and converges to a fixed value for different two-atom distances with evolution time. Furthermore, weak measurement reversal is employed to control the entropic uncertainty.

  20. Non-invasive method for screening and early detection of breast tumors using thermal field analysis

    Directory of Open Access Journals (Sweden)

    O. Drosu

    2009-10-01

    Full Text Available The paper refers to general presentation of international and European evaluation regarding breast cancer incidence and mortality as well as recommendations for prevention, screening, detection and treatment.The past years international research development in biomedical engineering has put a particular emphasis on the thermography use in breast pathology diagnosis and its main advantages, such as: an early diagnose of the breast cancer, in that stage when the mammography or ultrasounds can not easily detect the changes of the tissue; a totally non-invasive interaction with human body; very low costs and possibilities for the women to do a self thermographic test.We also present some important results of our research within the field of breast tumor detection using the numerical analysis of the thermal inverse problem.

  1. Development of a field measurement methodology for studying the thermal indoor environment in hybrid GEOTABS buildings

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk; Khovalyg, Dolaana; Olesen, Bjarne W.

    2018-01-01

    buildings. The three demonstration buildings were an office building in Luxembourg, an elderly care home in Belgium, and an elementary school in Czech Republic. All of these buildings are equipped with hybrid GEOTABS systems; however, they vary in size and function, which requires a unique measurement...... methodology for studying them. These buildings already have advanced Building Management Systems (BMS); however, a more detailed measurement plan was needed for the purposes of the project to document the current performance of these systems regarding thermal indoor environment and energy performance......, and to be able to document the improvements after the implementation of the MPC. This study provides the details of the developed field measurement methodology for each of these buildings to study the indoor environmental quality (IEQ) in details. The developed measurement methodology can be applied to other...

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

    International Nuclear Information System (INIS)

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

    2004-01-01

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

  3. Thermal interaction of the core and the mantle and long-term behavior of the geomagnetic field

    Science.gov (United States)

    Jones, G. M.

    1977-01-01

    The effects of temperature changes at the earth's core-mantle boundary on the velocity field of the core are analyzed. It is assumed that the geomagnetic field is maintained by thermal convection in the outer core. A model for the thermal interaction of the core and the mantle is presented which is consistent with current views on the presence of heat sources in the core and the properties of the lower mantle. Significant long-term variations in the frequency of geomagnetic reversals may be the result of fluctuating temperatures at the core-mantle boundary, caused by intermittent convection in the lower mantle. The thermal structure of the lower mantle region D double prime, extending from 2700 to 2900 km in depth, constitutes an important test of this hypothesis and offers a means of deciding whether the geomagnetic dynamo is thermally driven.

  4. The field theory of symmetrical layered electrolytic systems and the thermal Casimir effect

    International Nuclear Information System (INIS)

    Dean, D S; Horgan, R R

    2005-01-01

    We present a general extension of a field-theoretic approach developed in earlier papers to the calculation of the free energy of symmetrically layered electrolytic systems which is based on the sine-Gordon field theory for the Coulomb gas. The method is to construct the partition function in terms of the Feynman evolution kernel in the Euclidean time variable associated with the coordinate normal to the surfaces defining the layered structure. The theory is applicable to cylindrical systems and its development is motivated by the possibility that a static van der Waals or thermal Casimir force could provide an attractive force stabilizing a dielectric tube formed from a lipid bilayer, an example of which is provided by the t-tubules occurring in certain muscle cells. In this context, we apply the theory to the calculation of the thermal Casimir effect for a dielectric tube of radius R and thickness δ formed from such a membrane in water. In a grand canonical approach we find that the leading contribution to the Casimir energy behaves like -k B TLκ C /R which gives rise to an attractive force which tends to contract the tube radius. We find that κ C ∼0.3 for the case of typical lipid membrane t-tubules. We conclude that except in the case of a very soft membrane this force is insufficient to stabilize such tubes against the bending stress which tends to increase the radius. We briefly discuss the role of the lipid membrane reservoir implicit in the approach and whether its nature in biological systems may possibly lead to a stabilizing mechanism for such lipid tubes

  5. PIC Simulations of Velocity-space Instabilities in a Decreasing Magnetic Field: Viscosity and Thermal Conduction

    Science.gov (United States)

    Riquelme, Mario; Quataert, Eliot; Verscharen, Daniel

    2018-02-01

    We use particle-in-cell (PIC) simulations of a collisionless, electron–ion plasma with a decreasing background magnetic field, {\\boldsymbol{B}}, to study the effect of velocity-space instabilities on the viscous heating and thermal conduction of the plasma. If | {\\boldsymbol{B}}| decreases, the adiabatic invariance of the magnetic moment gives rise to pressure anisotropies with {p}| | ,j> {p}\\perp ,j ({p}| | ,j and {p}\\perp ,j represent the pressure of species j (electron or ion) parallel and perpendicular to B ). Linear theory indicates that, for sufficiently large anisotropies, different velocity-space instabilities can be triggered. These instabilities in principle have the ability to pitch-angle scatter the particles, limiting the growth of the anisotropies. Our simulations focus on the nonlinear, saturated regime of the instabilities. This is done through the permanent decrease of | {\\boldsymbol{B}}| by an imposed plasma shear. We show that, in the regime 2≲ {β }j≲ 20 ({β }j\\equiv 8π {p}j/| {\\boldsymbol{B}}{| }2), the saturated ion and electron pressure anisotropies are controlled by the combined effect of the oblique ion firehose and the fast magnetosonic/whistler instabilities. These instabilities grow preferentially on the scale of the ion Larmor radius, and make {{Δ }}{p}e/{p}| | ,e≈ {{Δ }}{p}i/{p}| | ,i (where {{Δ }}{p}j={p}\\perp ,j-{p}| | ,j). We also quantify the thermal conduction of the plasma by directly calculating the mean free path of electrons, {λ }e, along the mean magnetic field, finding that {λ }e depends strongly on whether | {\\boldsymbol{B}}| decreases or increases. Our results can be applied in studies of low-collisionality plasmas such as the solar wind, the intracluster medium, and some accretion disks around black holes.

  6. Temporal behaviour of self generated magnetic field and its influence on inhibition of thermal flux in ICF plasma

    International Nuclear Information System (INIS)

    Jha, L.N.

    1989-06-01

    The self generated magnetic field of megagauss order is reported to play a crucial role in ICF target designs because of its strong influence on the transport of energy from the critical density region to the ablation layer. The inhibition of the thermal flux due to such a field, thus, affects the whole of the other phenomenon of ICF. The knowledge of the proper variation of the magnetic field may help in assigning the existing controversial value of flux limit, f. Many papers dealing with the spatial variation of such a field exist and are well documented but the study on the variation of self generated field with time is rare. Here, the spatial variation of the megagauss field generated in the corona of a wire target irradiated by a laser as well as a model to study the temporal nature of the B-field at the peak have been obtained by solving the self inhibited diffusion which is regarded as the most dominant mechanism by which the thermal transport is influenced. The field exists for about ten nanoseconds even after the laser is switched off. The ratio of the two components of the thermal conductivity is also plotted against time and shows the inhibition. So, a track on the B-field variation both in space and time is necessary to keep for at least a few nanoseconds for computation of f. (author). 19 refs, 4 figs

  7. Adaptive optics correction into single mode fiber for a low Earth orbiting space to ground optical communication link using the OPALS downlink.

    Science.gov (United States)

    Wright, Malcolm W; Morris, Jeffery F; Kovalik, Joseph M; Andrews, Kenneth S; Abrahamson, Matthew J; Biswas, Abhijit

    2015-12-28

    An adaptive optics (AO) testbed was integrated to the Optical PAyload for Lasercomm Science (OPALS) ground station telescope at the Optical Communications Telescope Laboratory (OCTL) as part of the free space laser communications experiment with the flight system on board the International Space Station (ISS). Atmospheric turbulence induced aberrations on the optical downlink were adaptively corrected during an overflight of the ISS so that the transmitted laser signal could be efficiently coupled into a single mode fiber continuously. A stable output Strehl ratio of around 0.6 was demonstrated along with the recovery of a 50 Mbps encoded high definition (HD) video transmission from the ISS at the output of the single mode fiber. This proof of concept demonstration validates multi-Gbps optical downlinks from fast slewing low-Earth orbiting (LEO) spacecraft to ground assets in a manner that potentially allows seamless space to ground connectivity for future high data-rates network.

  8. Does exposure to a radiofrequency electromagnetic field modify thermal preference in juvenile rats?

    Science.gov (United States)

    Pelletier, Amandine; Delanaud, Stéphane; de Seze, René; Bach, Véronique; Libert, Jean-Pierre; Loos, Nathalie

    2014-01-01

    Some studies have shown that people living near a mobile phone base station may report sleep disturbances and discomfort. Using a rat model, we have previously shown that chronic exposure to a low-intensity radiofrequency electromagnetic field (RF-EMF) was associated with paradoxical sleep (PS) fragmentation and greater vasomotor tone in the tail. Here, we sought to establish whether sleep disturbances might result from the disturbance of thermoregulatory processes by a RF-EMF. We recorded thermal preference and sleep stage distribution in 18 young male Wistar rats. Nine animals were exposed to a low-intensity RF-EMF (900 MHz, 1 V x m(-1)) for five weeks and nine served as non-exposed controls. Thermal preference was assessed in an experimental chamber comprising three interconnected compartments, in which the air temperatures (Ta) were set to 24°C, 28°C and 31°C. Sleep and tail skin temperature were also recorded. Our results indicated that relative to control group, exposure to RF-EMF at 31°C was associated with a significantly lower tail skin temperature (-1.6°C) which confirmed previous data. During the light period, the exposed group preferred to sleep at Ta = 31°C and the controls preferred Ta = 28°C. The mean sleep duration in exposed group was significantly greater (by 15.5%) than in control group (due in turn to a significantly greater amount of slow wave sleep (SWS, +14.6%). Similarly, frequency of SWS was greater in exposed group (by 4.9 episodes.h-1). The PS did not differ significantly between the two groups. During the dark period, there were no significant intergroup differences. We conclude that RF-EMF exposure induced a shift in thermal preference towards higher temperatures. The shift in preferred temperature might result from a cold thermal sensation. The change in sleep stage distribution may involve signals from thermoreceptors in the skin. Modulation of SWS may be a protective adaptation in response to RF-EMF exposure.

  9. Does exposure to a radiofrequency electromagnetic field modify thermal preference in juvenile rats?

    Directory of Open Access Journals (Sweden)

    Amandine Pelletier

    Full Text Available Some studies have shown that people living near a mobile phone base station may report sleep disturbances and discomfort. Using a rat model, we have previously shown that chronic exposure to a low-intensity radiofrequency electromagnetic field (RF-EMF was associated with paradoxical sleep (PS fragmentation and greater vasomotor tone in the tail. Here, we sought to establish whether sleep disturbances might result from the disturbance of thermoregulatory processes by a RF-EMF. We recorded thermal preference and sleep stage distribution in 18 young male Wistar rats. Nine animals were exposed to a low-intensity RF-EMF (900 MHz, 1 V x m(-1 for five weeks and nine served as non-exposed controls. Thermal preference was assessed in an experimental chamber comprising three interconnected compartments, in which the air temperatures (Ta were set to 24°C, 28°C and 31°C. Sleep and tail skin temperature were also recorded. Our results indicated that relative to control group, exposure to RF-EMF at 31°C was associated with a significantly lower tail skin temperature (-1.6°C which confirmed previous data. During the light period, the exposed group preferred to sleep at Ta = 31°C and the controls preferred Ta = 28°C. The mean sleep duration in exposed group was significantly greater (by 15.5% than in control group (due in turn to a significantly greater amount of slow wave sleep (SWS, +14.6%. Similarly, frequency of SWS was greater in exposed group (by 4.9 episodes.h-1. The PS did not differ significantly between the two groups. During the dark period, there were no significant intergroup differences. We conclude that RF-EMF exposure induced a shift in thermal preference towards higher temperatures. The shift in preferred temperature might result from a cold thermal sensation. The change in sleep stage distribution may involve signals from thermoreceptors in the skin. Modulation of SWS may be a protective adaptation in response to RF-EMF exposure.

  10. Remotely Characterizing the Topographic and Thermal Evolution of Kīlauea's Lava Flow Field

    Science.gov (United States)

    Rumpf, M. E.; Vaughan, R. G.; Poland, M. P.

    2017-12-01

    New technologies in satellite data acquisition and the continuous development of analysis software capabilities are greatly improving the ability of scientists to monitor volcanoes in near-real-time. Satellite-based thermal infrared (TIR) data are used to monitor and analyze new and ongoing volcanic activity by identifying and quantifying surface thermal characteristics and lava flow discharge rates. Improved detector sensitivities provide unprecedented spatial detail in visible to shortwave infrared (VSWIR) satellite imagery. The acquisition of stereo and tri-stereo visible imagery, as well as SAR, by an increasing number of satellite systems enables the creation of digital elevation models (DEMs) at higher temporal frequencies and resolutions than in the past. Free, user-friendly software programs, such as NASA's Ames Stereo Pipeline and Google Earth Engine, ease the accessibility and usability of satellite data to users unfamiliar with traditional analysis techniques. An effective and efficient integration of these technologies can be utilized towards volcano monitoring.Here, we use the active lava flows from the East Rift Zone vents of Kīlauea Volcano, Hawai`i as a testing ground for developing new techniques in multi-sensor volcano remote sensing. We use DEMs generated from stereo and tri-stereo images captured by the WorldView3 and Pleiades satellite systems to assess topographic changes over time at the active flow fields. Time-series data of lava flow area, thickness, and discharge rate developed from thermal emission measurements collected by ASTER, Landsat 8, and WorldView3 are compared to satellite-detected topographic changes and to ground observations of flow development to identify behavioral patterns and to monitor flow field evolution. We explore methods of combining these visual and TIR data sets collected by multiple satellite systems with a variety of resolutions and repeat times. Our ultimate goal is to develop integrative tools for near

  11. Thermal modeling of step-out targets at the Soda Lake geothermal field, Churchill County, Nevada

    Science.gov (United States)

    Dingwall, Ryan Kenneth

    Temperature data at the Soda Lake geothermal field in the southeastern Carson Sink, Nevada, highlight an intense thermal anomaly. The geothermal field produces roughly 11 MWe from two power producing facilities which are rated to 23 MWe. The low output is attributed to the inability to locate and produce sufficient volumes of fluid at adequate temperature. Additionally, the current producing area has experienced declining production temperatures over its 40 year history. Two step-out targets adjacent to the main field have been identified that have the potential to increase production and extend the life of the field. Though shallow temperatures in the two subsidiary areas are significantly less than those found within the main anomaly, measurements in deeper wells (>1,000 m) show that temperatures viable for utilization are present. High-pass filtering of the available complete Bouguer gravity data indicates that geothermal flow is present within the shallow sediments of the two subsidiary areas. Significant faulting is observed in the seismic data in both of the subsidiary areas. These structures are highlighted in the seismic similarity attribute calculated as part of this study. One possible conceptual model for the geothermal system(s) at the step-out targets indicated upflow along these faults from depth. In order to test this hypothesis, three-dimensional computer models were constructed in order to observe the temperatures that would result from geothermal flow along the observed fault planes. Results indicate that the observed faults are viable hosts for the geothermal system(s) in the step-out areas. Subsequently, these faults are proposed as targets for future exploration focus and step-out drilling.

  12. Effects of {gamma} and neutron irradiation on the optical absorption of pure silica core single-mode optical fibres from Nufern

    Energy Technology Data Exchange (ETDEWEB)

    Calderon, A. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Martinez-Rivero, C. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Matorras, F. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Rodrigo, T. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Sobron, M. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Vila, I. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Virto, A.L. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Alberdi, J. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Arce, P. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Barcala, J.M. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Calvo, E. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Ferrando, A. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain)]. E-mail: Antonio.Ferrando@ciemat.es; Josa, M.I. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Luque, J.M. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Molinero, A. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Navarrete, J. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Oller, J.C. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Valdivieso, P. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Yuste, C. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Fenyvesi, A. [Institute of Nuclear Research, ATOMKI, Debrecen (Hungary); Molnar, J. [Institute of Nuclear Research, ATOMKI, Debrecen (Hungary)

    2006-09-15

    A measurement of the optical absorption, induced by photon irradiation up to a dose of 0.9 MGy, in Nufern silica core single-mode optical fibres is presented. In addition, the fibres were irradiated with neutrons, up to a total fluence of 2x10{sup 14} cm{sup -2} and the induced optical absorption was evaluated for four different wavelengths: 630, 670, 681 and 785 nm.

  13. Effects of γ and neutron irradiation on the optical absorption of pure silica core single-mode optical fibres from Nufern

    International Nuclear Information System (INIS)

    Calderon, A.; Martinez-Rivero, C.; Matorras, F.; Rodrigo, T.; Sobron, M.; Vila, I.; Virto, A.L.; Alberdi, J.; Arce, P.; Barcala, J.M.; Calvo, E.; Ferrando, A.; Josa, M.I.; Luque, J.M.; Molinero, A.; Navarrete, J.; Oller, J.C.; Valdivieso, P.; Yuste, C.; Fenyvesi, A.; Molnar, J.

    2006-01-01

    A measurement of the optical absorption, induced by photon irradiation up to a dose of 0.9 MGy, in Nufern silica core single-mode optical fibres is presented. In addition, the fibres were irradiated with neutrons, up to a total fluence of 2x10 14 cm -2 and the induced optical absorption was evaluated for four different wavelengths: 630, 670, 681 and 785 nm

  14. Coupled-Mode Theory derivation of the formal equivalence between a three-mode waveguide and a set of three mutually coupled single-mode waveguides

    Directory of Open Access Journals (Sweden)

    Boucher Yann G.

    2017-01-01

    Full Text Available The formal identification between a two-mode waveguide and a system of two mutually coupled single-mode waveguides stems from the symmetries of the evolution operator. When the gap tends to zero, the super-modes of the coupled system merge continuously into the modes of the multimode waveguide. For modelling purposes, it is very tempting to extend the analogy to three-mode waveguides (and beyond. But not without some precautions…

  15. Application methods of infrared thermal images in the health care field of traditional Chinese medicine

    Science.gov (United States)

    Li, Ziru; Zhang, Xusheng

    2008-12-01

    Infrared thermal imaging (ITI) is the potential imaging technique for the health care field of traditional Chinese medicine (TCM). Successful application demands obeying the characteristics and regularity of the ITI of human body and designing rigorous trials. First, the influence of time must be taken into account as the ITI of human body varies with time markedly. Second, relative magnitude is preferred to be the index of the image features. Third, scatter diagrams and the method of least square could present important information for evaluating the health care effect. A double-blind placebo-controlled randomized trial was undertaken to study the influences of Shengsheng capsule, one of the TCM health food with immunity adjustment function, on the ITI of human body. The results showed that the effect of Shengsheng capsule to people with weak constitution or in the period of being weak could be reflected objectively by ITI. The relative efficacy rate was 81.3% for the trial group and 30.0% for the control group, there was significant difference between the two groups (P=0.003). So the sensitivity and objectivity of ITI are of great importance to the health care field of TCM.

  16. Self-consistent Optomechanical Dynamics and Radiation Forces in Thermal Light Fields

    International Nuclear Information System (INIS)

    Sonnleitner, M.

    2014-01-01

    We discuss two different aspects of the mechanical interaction between neutral matter and electromagnetic radiation.The first part addresses the complex dynamics of an elastic dielectric deformed by optical forces. To do so we use a one-dimensional model describing the medium by an array of beam splitters such that the interaction with the incident waves can be described with a transfer-matrix approach. Since the force on each individual beam splitter is known we thus obtain the correct volumetric force density inside the medium. Sending a light field through an initially homogeneous dielectric then results in density modulations which in turn alter the optical properties of this medium.The second part is concerned with mechanical light-effects on atoms in thermal radiation fields. At hand of a generic setup of an atom interacting with a hot sphere emitting blackbody radiation we show that the emerging gradient force may surpass gravity by several orders of magnitude. The strength of the repulsive scattering force strongly depends on the spectrum of the involved atoms and can be neglected in some setups. A special emphasis lies on possible implications on astrophysical scenarios where the interactions between heated dust and atoms, molecules or nanoparticles are of crucial interest. (author) [de

  17. Self-Field Effects in Magneto-Thermal Instabilities for Nb-Sn Strands

    CERN Document Server

    Bordini, B; Fehér, S; Rossi, L; Zlobin, A V

    2008-01-01

    Recent advancements in the critical current density (Jc) of Nb$_{3}$Sn conductors, coupled with a large effective filament size, have drawn attention to the problem of magnetothermal instabilities. At low magnetic fields, the quench current of such high Jc Nb$_{3}$Sn strands is significantly lower than their critical current because of the above-mentioned instabilities. An adiabatic model to calculate the minimum current at which a strand can quench due to magneto-thermal instabilities is developed. The model is based on an 'integral' approach already used elsewhere [1]. The main difference with respect to the previous model is the addition of the self-field effect that allows to describe premature quenches of non-magnetized Nb$_{3}$Sn strands and to better calculate the quench current of strongly magnetized strands. The model is in good agreement with experimental results at 4.2 K obtained at Fermilab using virgin Modified Jelly Roll (MJR) strands with a low Residual Resistivity Ratio (RRR) of the stabilizin...

  18. SPECTRUM WEIGHTED RESPONSES OF SEVERAL DETECTORS IN MIXED FIELDS OF FAST AND THERMAL NEUTRONS

    Directory of Open Access Journals (Sweden)

    SANG IN KIM

    2014-04-01

    Full Text Available The spectrum weighted responses of various detectors were calculated to provide guidance on the proper selection and use of survey instruments on the basis of their energy response characteristics on the neutron fields. To yield the spectrum weighted response, the detector response functions of 17 neutron-measuring devices were numerically folded with each of the produced calibration neutron spectra through the in-house developed software ‘K-SWR’. The detectors’ response functions were taken from the IAEA Technical Reports Series No. 403 (TRS-403. The reference neutron fields of 21 kinds with 2 spectra groups with different proportions of thermal and fast neutrons have been produced using neutrons from the 241Am-Be sources held in a graphite pile, a bare 241Am-Be source, and a DT neutron generator. Fluence-average energy (Eave varied from 3.8 MeV to 16.9 MeV, and the ambient-dose-equivalent rate [H*(10/h] varied from 0.99 to 16.5 mSv/h.

  19. Effects of high intensity pulsed electric field and thermal treatments on a lipase from Pseudomonas fluorescens.

    Science.gov (United States)

    Bendicho, S; Estela, C; Giner, J; Barbosa-Cánovas, G V; Martin, O

    2002-01-01

    Milk and dairy products may contain microorganisms capable of secreting lipases that cause sensory defects and technological problems in the dairy industry. In this study, the effects of thermal and high-intensity pulsed electric field (HIPEF) treatments on an extracellular lipase from Pseudomonas fluorescens, suspended in a simulated skim milk ultrafiltrate (SMUF) have been evaluated. Heat treatments applied were up to 30 min from 50 to 90 degrees C. HIPEF treatments were carried out using pilot plant facilities in a batch or continuous flow mode, where treatment chambers consisted of parallel and coaxial configuration, respectively. Samples were subjected to up to 80 pulses at electric field intensities ranging from 16.4 to 37.3 kV/cm. This resulted in a lipase that was quite resistant to heat and also to HIPEF. High (75 degrees C-15 s) and low pasteurization treatments (63 degrees C-30 min) led to inactivations of 5 and 20%, respectively. Using the batch-mode HIPEF equipment, a 62.1% maximum activity depletion was achieved after 80 pulses at 27.4 kV/cm. However, when HIPEF treatments were applied in the continuous flow mode, an inactivation rate of just 13% was achieved, after applying 80 pulses at 37.3 kV/cm and 3.5 Hz. The results of both heat and HIPEF treatments on enzyme inactivation were adjusted with good agreement to a first-order kinetic model (R2 > 62.3%).

  20. Feeble magnetic fields generated by thermal charge fluctuations in extended metallic conductors: Implications for electric-dipole moment experiments

    International Nuclear Information System (INIS)

    Lamoreaux, S.K.

    1999-01-01

    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 199 Hg. 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

  1. The effects of dune slopes and material heterogeneity on the thermal behavior of dune fields in Mars' Southern Hemisphere

    Science.gov (United States)

    O'Shea, P. M.; Putzig, N. E.; Van Kooten, S.; Fenton, L. K.

    2015-12-01

    We analyzed the effects of slopes on the thermal properties of three dune fields in Mars' southern hemisphere. Although slope has important thermal effects, it is not the main driver of observed apparent thermal inertia (ATI) for these dunes. Comparing the ATI seasonal behavior as derived from Thermal Emission Spectrometer (TES) data with that modeled for compositional heterogeneities, we found that TES results correlate best with models of duricrust overlying and/or horizontally mixing with fines. We measured slopes and aspects in digital terrain models created from High Resolution Imaging Science Experiment (HiRISE) images of dunes within Proctor, Kaiser, and Wirtz craters. Using the MARSTHERM web toolset, we incorporated the slopes and aspects together with TES albedo, TES thermal inertia, surface pressure, and TES dust opacity, into models of seasonal ATI. Models that incorporate sub-pixel slopes show seasonal day and night ATI values that differ from the TES results by 0-300 J m-2 K-1 s-½. In addition, the models' day-night differences are opposite in sign from those of the TES results, indicating that factors other than slope are involved. We therefore compared the TES data to model results for a broad range of horizontally mixed and two-layered surfaces to seek other possible controls on the observed data, finding that a surface layer of higher thermal inertia is a likely contributor. However, it is clear from this study that the overall composition and morphology of the dune fields are more complex than currently available models allow. Future work will combine slopes with other model parameters such as multi-layered surfaces and lateral changes in layer thickness. Coupling these improvements with broader seasonal coverage from the Thermal Emission Imaging System (THEMIS) at more thermally favorable times of day would allow more accurate characterization of dune thermal behavior.

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

    International Nuclear Information System (INIS)

    Frischauf, Norbert; Hettmer, Manfred; Grassauer, Andreas; Bartusch, Tobias; Koudelka, Otto

    2006-01-01

    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)

  3. Modeling coupled thermal, flow, transport and geochemical processes controlling near field long-term evolution

    International Nuclear Information System (INIS)

    Zhou, W.; Arthur, R.; Xu, T.; Pruess, K.

    2005-01-01

    Full text of publication follows: Bentonite is planned for use as a buffer material in the Swedish nuclear waste disposal concept (KBS-3). Upon emplacement, the buffer is expected to experience a complex set of coupled processes involving heating, re-saturation, reaction and transport of groundwater imbibed from the host rock. The effect of these processes may eventually lead to changes in desirable physical and rheological properties of the buffer, but these processes are not well understood. In this paper, a new quantitative model is evaluated to help improve our understanding of the long-term performance of buffer materials. This is an extension of a previous study [1] that involved simple thermal and chemical models applied to a fully saturated buffer. The thermal model in the present study uses heating histories for spent fuel in a single waste package [2]. The model uses repository dimensions, such as borehole and tunnel spacings [2], which affect the temperature distribution around the waste package. At the time of emplacement, bentonite is partially saturated with water having a different composition than the host-rock groundwater. The present model simulates water imbibition from the host rock into the bentonite under capillary and hydraulic pressure gradients. The associated chemical reactions and solute transport are simulated using Aespoe water composition [3]. The initial mineralogy of bentonite is assumed to be dominated by Na-smectite with much smaller amounts of anhydrite and calcite. Na-smectite dissolution is assumed to be kinetically-controlled while all other reactions are assumed to be at equilibrium controlled. All equilibrium and kinetic constants are temperature dependent. The modeling tool used is TOUGHREACT, developed by Lawrence Berkeley National Laboratory [4]. TOUGHREACT is a numerical model that is well suited for near-field simulations because it accounts for feedback between porosity and permeability changes from mineral

  4. Characterization of thermal neutron fields for calibration of neutron monitors in accordance with great equivalent dose environment H⁎(10)

    International Nuclear Information System (INIS)

    Silva, Larissa P. S. da; Silva, Felipe S.; Fonseca, Evaldo S.; Patrao, Karla C.S.; Pereira, Walsan W.

    2017-01-01

    The Laboratório Brasileiro de Nêutrons do Instituto de Radioproteção e Dosimetria (IRD/CNEN) has developed and built a thermal neutron flux facility to provide neutron fluence for dosimeters (Astuto, 2014). This fluency is obtained by four 16 Ci sources 241 AmBe (α, n) positioned around the channel positioned in the center of the Thermal Flow Unit (UFT). The UFT was built with blocks of paraffin with graphite addition and graphite blocks of high purity to obtain a central field with a homogeneous thermal neutron fluence for calibration purposes with the following measurements: 1.2 x 1.2 x 1.2 m 3 . The objective of this work is to characterize several points, in the thermal energy range, in terms of the equivalent ambient dose quantity H⁎(10) for calibration and irradiation of monitors neutrons

  5. Increasing Heavy Oil Reserves in the Wilmington Oil Field Through Advanced Reservoir Characterization and Thermal Production Technologies, Class III

    Energy Technology Data Exchange (ETDEWEB)

    City of Long Beach; Tidelands Oil Production Company; University of Southern California; David K. Davies and Associates

    2002-09-30

    The objective of this project was to increase the recoverable heavy oil reserves within sections of the Wilmington Oil Field, near Long Beach, California through the testing and application of advanced reservoir characterization and thermal production technologies. It was hoped that the successful application of these technologies would result in their implementation throughout the Wilmington Field and, through technology transfer, will be extended to increase the recoverable oil reserves in other slope and basin clastic (SBC) reservoirs.

  6. Effects of X irradiation and high field electron injection of the electrical properties of rapid thermal oxides

    International Nuclear Information System (INIS)

    Schubert, W.K.; Seager, C.H.

    1988-01-01

    Rapid thermal oxidation (RTO) is a promising tool for fabricating the thin gate oxides (5 to 15 nm) that will be needed in future submicron integrated circuits, because of its inherently superior time-temperature control when compared to conventional oxidation methods. It is important to demonstrate that RTO can be used without adversely affecting the radiation hardness or high field properties of the oxide. Beyond this demonstration, rapid thermal processing makes it possible to determine more precisely how the kinetics of oxidation and post oxidation annealing affect the device properties. Information of this type should prove useful in modeling relevant defect formation mechanisms. The present paper is part of a systematic study of the effect of rapid thermal processing on the radiation and high field response of thin oxides

  7. Active Radiative Thermal Switching with Graphene Plasmon Resonators.

    Science.gov (United States)

    Ilic, Ognjen; Thomas, Nathan H; Christensen, Thomas; Sherrott, Michelle C; Soljačić, Marin; Minnich, Austin J; Miller, Owen D; Atwater, Harry A

    2018-03-27

    We theoretically demonstrate a near-field radiative thermal switch based on thermally excited surface plasmons in graphene resonators. The high tunability of graphene enables substantial modulation of near-field radiative heat transfer, which, when combined with the use of resonant structures, overcomes the intrinsically broadband nature of thermal radiation. In canonical geometries, we use nonlinear optimization to show that stacked graphene sheets offer improved heat conductance contrast between "ON" and "OFF" switching states and that a >10× higher modulation is achieved between isolated graphene resonators than for parallel graphene sheets. In all cases, we find that carrier mobility is a crucial parameter for the performance of a radiative thermal switch. Furthermore, we derive shape-agnostic analytical approximations for the resonant heat transfer that provide general scaling laws and allow for direct comparison between different resonator geometries dominated by a single mode. The presented scheme is relevant for active thermal management and energy harvesting as well as probing excited-state dynamics at the nanoscale.

  8. Field evaluation of indoor thermal fog and ultra-low volume applications for control of Aedes aegypti, in Thailand

    Science.gov (United States)

    Efficacies of a hand-held thermal fogger (PatriotTM) and hand-held Ultra-low volume (ULV) sprayer (TwisterTM) with combinations of two different adulticides and an insect growth regulator (pyriproxyfen) were field assessed and compared for their impact on reducing dengue vector populations in Thaila...

  9. Evaluate depth of field limits of fixed focus lens arrangements in thermal infrared

    Science.gov (United States)

    Schuster, Norbert

    2016-05-01

    More and more modern thermal imaging systems use uncooled detectors. High volume applications work with detectors that have a reduced pixel count (typically between 200x150 and 640x480). This reduces the usefulness of modern image treatment procedures such as wave front coding. On the other hand, uncooled detectors demand lenses with fast fnumbers, near f/1.0, which reduces the expected Depth of Field (DoF). What are the limits on resolution if the target changes distance to the camera system? The desire to implement lens arrangements without a focusing mechanism demands a deeper quantification of the DoF problem. A new approach avoids the classic "accepted image blur circle" and quantifies the expected DoF by the Through Focus MTF of the lens. This function is defined for a certain spatial frequency that provides a straightforward relation to the pixel pitch of imaging device. A certain minimum MTF-level is necessary so that the complete thermal imaging system can realize its basic functions, such as recognition or detection of specified targets. Very often, this technical tradeoff is approved with a certain lens. But what is the impact of changing the lens for one with a different focal length? Narrow field lenses, which give more details of targets in longer distances, tighten the DoF problem. A first orientation is given by the hyperfocal distance. It depends in a square relation on the focal length and in a linear relation on the through focus MTF of the lens. The analysis of these relations shows the contradicting requirements between higher thermal and spatial resolution, faster f-number and desired DoF. Furthermore, the hyperfocal distance defines the DoF-borders. Their relation between is such as the first order imaging formulas. A calculation methodology will be presented to transfer DoF-results from an approved combination lens and camera to another lens in combination with the initial camera. Necessary input for this prediction is the accepted DoF of

  10. Numerical modeling of thermal regime in inland water bodies with field measurement data

    Science.gov (United States)

    Gladskikh, D.; Sergeev, D.; Baydakov, G.; Soustova, I.; Troitskaya, Yu.

    2018-01-01

    Modification of the program complex LAKE, which is intended to compute the thermal regimes of inland water bodies, and the results of its validation in accordance with the parameters of lake part of Gorky water reservoir are reviewed in the research. The modification caused changing the procedure of input temperature profile assignment and parameterization of surface stress on air-water boundary in accordance with the consideration of wind influence on mixing process. Also the innovation consists in combined methods of gathering meteorological parameters from files of global meteorological reanalysis and data of hydrometeorological station. Temperature profiles carried out with CTD-probe during expeditions in the period 2014-2017 were used for validation of the model. The comparison between the real data and the numerical results and its assessment based on time and temperature dependences in control points, correspondence of the forms of the profiles and standard deviation for all performed realizations are provided. It is demonstrated that the model reproduces the results of field measurement data for all observed conditions and seasons. The numerical results for the regimes with strong mixing are in the best quantitative and qualitative agreement with the real profiles. The accuracy of the forecast for the ones with strong stratification near the surface is lower but all specificities of the forms are correctly reproduced.

  11. Thermalization and revivals after a quantum quench in conformal field theory.

    Science.gov (United States)

    Cardy, John

    2014-06-06

    We consider a quantum quench in a finite system of length L described by a 1+1-dimensional conformal field theory (CFT), of central charge c, from a state with finite energy density corresponding to an inverse temperature β≪L. For times t such that ℓ/2thermal density matrix. We compute exactly the overlap F of the state at time t with the initial state and show that in general it is exponentially suppressed at large L/β. However, for minimal models with c<1 (more generally, rational CFTs), at times which are integer multiples of L/2 (for periodic boundary conditions, L for open boundary conditions) there are (in general, partial) revivals at which F is O(1), leading to an eventual complete revival with F=1. There is also interesting structure at all rational values of t/L, related to properties of the CFT under modular transformations. At early times t≪(Lβ)^{1/2} there is a universal decay F∼exp(-(πc/3)Lt^{2}/β(β^{2}+4t^{2})). The effect of an irrelevant nonintegrable perturbation of the CFT is to progressively broaden each revival at t=nL/2 by an amount O(n^{1/2}).

  12. GoAmazon 2014/15 Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) Field Campaign Report

    Energy Technology Data Exchange (ETDEWEB)

    Smith, JN [Univ. of California, Irvine, CA (United States)

    2016-04-01

    The Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) deployment to the U.S. Department of Energy (DOE)’s Atmospheric Radiation Measurement (ARM) Climate Research Facility T3 site in Manacapuru, Brazil, was motivated by two main scientific objectives of the Green Ocean Amazon (GoAmazon) 2014/15 field campaign. 1) Study the interactions between anthropogenic and biogenic emissions by determining important molecular species in ambient nanoparticles. To address this, TDCIMS data will be combined with coincident measurements such as gas-phase sulfuric acid to determine the contribution of sulfuric acid condensation to nucleation and growth. We can then compare that result to TDCIMS-derived nanoparticle composition to determine the fraction of growth that can be attributed to the uptake of organic compounds. The molecular composition of sampled particles will also be used to attribute specific chemical species and mechanisms to growth, such as the condensation of low-volatility species or the oligomerization of α-dicarbonyl compounds. 2) Determine the source of new ambient nanoparticles in the Amazon. The hypothesis prior to measurements was that potassium salts formed from the evaporation of primary particles emitted by fungal spores can provide a unique and important pathway for new particle production in the Amazon basin. To explore this hypothesis, the TDCIMS recorded the mass spectra of sampled ambient particles using a protonated water cluster Chemical Ionization Mass Spectrometer (CIMS). Laboratory tests performed using potassium salts show that the TDCIMS can detect potassium with high sensitivity with this technique.

  13. Retarded Propagator Representation of Out-of-Equilibrium Thermal Field Theories

    International Nuclear Information System (INIS)

    Dadic, I.

    2009-01-01

    We represent out of equilibrium thermal field theories with finite time path in terms of retarded propagators exclusively. For the particle number, defined as the equal time limit of the Keldysh propagator, the time ordering of the diagrams contributing is particularly simple: all external end-points of propagators have maximal time, there are no internal vertices with locally maximal time, the property which guaranties causality), there is, at least one 'sink' vertex (vertex with locally minimal time). The diagram looks like fisher net hanging on external vertices. At the 'sink' vertices energy is not conserved, thus establishing realisation of uncertainty relations in out of equilibrium TFT. Even more, at the equal-time limit, the terms conserving energy at 'sink' vertices vanish. This fact eliminates pinching problem and enables safe time→∞ limit. The retarded propagator in higher orders is regularized only as a part of of the diagram connected to equal time limit of multi point Green function representing expectation value of the product of number operators. These properties indicate clear advantage of finite time path, in large time limit over the use of Keldysh time path.

  14. Thermal coupling of conjugate ionospheres and the tilt of the earth's magnetic field

    Science.gov (United States)

    Richards, P. G.; Torr, D. G.

    1986-01-01

    The effect of thermal coupling and the tilt of the earth's magnetic field on interhemispheric coupling is investigated, and, due to a longitudinal displacement in the conjugate points, it is found that the tilt significantly effects the upward flow of H(+) flux such that the maximum upward flux can occur several hours before local sunrise. Heating from the conjugate atmosphere, which accompanies solar illumination in one hemisphere, produces electron temperatures 1000 K higher in the dark than in the sunlit hemisphere, and the morning upward H(+) fluxes in the dark ionosphere are as large as the daytime fluxes. A strong symmetry is also noted in the overall behavior of the H(+) fluxes due to the differing day lengths at the conjugate points, which are separated by 15 deg in latitude. Electron temperatures in the conjugate hemispheres are found to be strongly coupled above the F region peaks, though in the vicinity of the peaks near 250 km, the coupling is weak during the day and strong during the night.

  15. Thermal and petrologic constraints on lower crustal melt accumulation under the Salton Sea Geothermal Field

    Science.gov (United States)

    Karakas, Ozge; Dufek, Josef; Mangan, Margaret T.; Wright, Heather M.; Bachmann, Olivier

    2017-06-01

    In the Salton Sea region of southern California (USA), concurrent magmatism, extension, subsidence, and sedimentation over the past 0.5 to 1.0 Ma have led to the creation of the Salton Sea Geothermal Field (SSGF)-the second largest and hottest geothermal system in the continental United States-and the small-volume rhyolite eruptions that created the Salton Buttes. In this study, we determine the flux of mantle-derived basaltic magma that would be required to produce the elevated average heat flow and sustain the magmatic roots of rhyolite volcanism observed at the surface of the Salton Sea region. We use a 2D thermal model to show that a lower-crustal, partially molten mush containing Salton Trough, and are consistent with seismic observations. Our results indicate limited melting and assimilation of pre-existing rocks in the lower crust. Instead, we find that basalt fractionation in the lower crust produces derivative melts of andesitic to dacitic composition. Such melts are then expected to ascend and accumulate in the upper crust, where they further evolve to give rise to small-volume rhyolite eruptions (Salton Buttes) and fuel local spikes in surface heat flux as currently seen in the SSGF. Such upper crustal magma evolution, with limited assimilation of hydrothermally altered material, is required to explain the slight decrease in δ18 O values of zircons (and melts) that have been measured in these rhyolites.

  16. Field study on behaviors and adaptation of elderly people and their thermal comfort requirements in residential environments.

    Science.gov (United States)

    Hwang, R-L; Chen, C-P

    2010-06-01

    This study investigated the thermal sensation of elderly people in Taiwan, older than 60 years, in indoor microclimate at home, and their requirements for establishing thermal comfort. The study was conducted using both a thermal sensation questionnaire and measurement of indoor climatic parameters underlying the thermal environment. Survey results were compared with those reported by Cheng and Hwang (2008, J. Tongji Univ., 38, 817-822) for non-elders to study the variation between different age groups in requirements of indoor thermal comfort. The results show that the predominant strategy of thermal adaptation for elders was window-opening in the summer and clothing adjustment in the winter. The temperature of thermal neutrality was 25.2 degrees C and 23.2 degrees C for the summer and the winter, respectively. Logistically regressed probit modeling on percentage of predicted dissatisfied (PPD) against mean thermal sensation vote revealed that the sensation votes corresponding to a PPD of 20% were +/- 0.75 for elders, about +/- 0.10 less than the levels projected by ISO 7730 model. The range of operative temperature for 80% thermal acceptability for elders in the summer was 23.2-27.1 degrees C, narrower than the range of 23.0-28.6 degrees C reported for non-elders. This is likely a result of a difference in the selection of adaptive strategies. Taiwan in the last decade has seen a rapid growth in the elderly population in its societal structure, and as such the quality of indoor thermal comfort increasingly concerns the elderly people. This study presents the results from field-surveying elders residing in major geographical areas of Taiwan, and discusses the requirements of these elders for indoor thermal comfort in different seasons. Through a comparison with the requirements by non-elders, this study demonstrates the unique sensitivity of elders toward indoor thermal quality and the selection of adaptive strategies that need to be considered when a thermal

  17. Optimal control of non-Markovian dynamics in a single-mode cavity strongly coupled to an inhomogeneously broadened spin ensemble

    Science.gov (United States)

    Krimer, Dmitry O.; Hartl, Benedikt; Mintert, Florian; Rotter, Stefan

    2017-10-01

    Ensembles of quantum-mechanical spins offer a promising platform for quantum memories, but proper functionality requires accurate control of unavoidable system imperfections. We present an efficient control scheme for a spin ensemble strongly coupled to a single-mode cavity based on a set of Volterra equations relying solely on weak classical control pulses. The viability of our approach is demonstrated in terms of explicit storage and readout sequences that will serve as a starting point towards the realization of more demanding full quantum-mechanical optimal control schemes.

  18. Hydrogeochemical Characteristics and Geothermometry Applications of Thermal Waters in Coastal Xinzhou and Shenzao Geothermal Fields, Guangdong, China

    Directory of Open Access Journals (Sweden)

    Xiao Wang

    2018-01-01

    Full Text Available Two separate groups of geothermal waters have been identified in the coastal region of Guangdong, China. One is Xinzhou thermal water of regional groundwater flow system in a granite batholith and the other is thermal water derived from shallow coastal aquifers in Shenzao geothermal field, characterized by high salinity. The hydrochemical characteristics of the thermal waters were examined and characterized as Na-Cl and Ca-Na-Cl types, which are very similar to that of seawater. The hydrochemical evolution is revealed by analyzing the correlations of components versus Cl and their relative changes for different water samples, reflecting different extents of water-rock interactions and clear mixing trends with seawaters. Nevertheless, isotopic data indicate that thermal waters are all of the meteoric origins. Isotopic data also allowed determination of different recharge elevations and presentation of different mixing proportions of seawater with thermal waters. The reservoir temperatures were estimated by chemical geothermometries and validated by fluid-mineral equilibrium calculations. The most reliable estimates of reservoir temperature lie in the range of 148–162°C for Xinzhou and the range of 135–144°C for Shenzao thermal waters, based on the retrograde and prograde solubilities of anhydrite and chalcedony. Finally, a schematic cross-sectional fault-hydrology conceptual model was proposed.

  19. Long-term vacuum tests of single-mode vertical cavity surface emitting laser diodes used for a scalar magnetometer

    Science.gov (United States)

    Hagen, C.; Ellmeier, M.; Piris, J.; Lammegger, R.; Jernej, I.; Magnes, W.; Murphy, E.; Pollinger, A.; Erd, C.; Baumjohann, W.

    2017-11-01

    Scalar magnetometers measure the magnitude of the magnetic field, while vector magnetometers (mostly fluxgate magnetometers) produce three-component outputs proportional to the magnitude and the direction of the magnetic field. While scalar magnetometers have a high accuracy, vector magnetometers suffer from parameter drifts and need to be calibrated during flight. In some cases, full science return can only be achieved by a combination of vector and scalar magnetometers.

  20. Coherence holography by achromatic 3-D field correlation of generic thermal light with an imaging Sagnac shearing interferometer.

    Science.gov (United States)

    Naik, Dinesh N; Ezawa, Takahiro; Singh, Rakesh Kumar; Miyamoto, Yoko; Takeda, Mitsuo

    2012-08-27

    We propose a new technique for achromatic 3-D field correlation that makes use of the characteristics of both axial and lateral magnifications of imaging through a common-path Sagnac shearing interferometer. With this technique, we experimentally demonstrate, for the first time to our knowledge, 3-D image reconstruction of coherence holography with generic thermal light. By virtue of the achromatic axial shearing implemented by the difference in axial magnifications in imaging, the technique enables coherence holography to reconstruct a 3-D object with an axial depth beyond the short coherence length of the thermal light.

  1. A comparative study of field-emission from different one dimensional carbon nanostructures synthesized via thermal CVD system

    International Nuclear Information System (INIS)

    Jha, A.; Banerjee, D.; Chattopadhyay, K.K.

    2011-01-01

    Different one dimensional (1D) carbon nanostructures, such as carbon nanonoodles (CNNs), carbon nanospikes (CNSs) and carbon nanotubes (CNTs) have been synthesized via thermal chemical vapour deposition (TCVD) technique. The different 1D morphologies were synthesized by varying the substrate material and the deposition conditions. The as-prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). FESEM and TEM images showed that the diameters of the CNNs and CNTs were ∼40 nm while the diameters of the CNSs were around 100 nm. Field emission studies of the as-prepared samples showed that CNSs to be a better field emitter than CNNs, whereas CNTs are the best among the three producing large emission current. The variation of field emission properties with inter-electrode distance has been studied in detail. Also the time dependent field emission studies of all the nanostructures have been carried out.

  2. Biochemical degradation and physical migration of polyphenolic compounds in osmotic dehydrated blueberries with pulsed electric field and thermal pretreatments.

    Science.gov (United States)

    Yu, Yuanshan; Jin, Tony Z; Fan, Xuetong; Wu, Jijun

    2018-01-15

    Fresh blueberries were pretreated by pulsed electric fields (PEF) or thermal pretreatment and then were subject to osmotic dehydration. The changes in contents of anthocyanins, predominantly phenolic acids and flavonols, total phenolics, polyphenol oxidase (PPO) activity and antioxidant activity in the blueberry samples during pretreatment and osmotic dehydration were investigated. Biochemical degradation and physical migration of these nutritive compounds from fruits to osmotic solutions were observed during the pretreatments and osmotic dehydration. PEF pretreated samples had the least degradation loss but the most migration loss of these compounds compared to thermally pretreated and control samples. Higher rates of water loss and solid gain during osmotic dehydration were also obtained by PEF pretreatment, reducing the dehydration time from 130 to 48h. PEF pretreated and dehydrated fruits showed superior appearance to thermally pretreated and control samples. Therefore, PEF pretreatment is a preferred technology that balances nutritive quality, appearance, and dehydration rate. Published by Elsevier Ltd.

  3. Single-mode pulsed dye laser pumped by using a diode-pumped Nd:YAG laser with a long pulse width

    CERN Document Server

    Yi, J H; Moon, H J; Rho, S P; Han, J M; Rhee, Y J; Lee, J M

    1999-01-01

    The lasing characteristics of a single-mode dye laser pumped by using a diode-pumped solid-state laser (DPSSL) with a high repetition rate is described. A 45-mm-long Nd:YAG rod was pumped by three CW diode arrays and it was acousto-optically Q-switched. A KTP crystal was used for intracavity frequency doubling. The pulse width of the laser ranged from 90 ns to 200 ns, depending on the diode current and the Q-switching frequency. The single-mode dye laser had a grazing incidence configuration. The pulse width of the dye laser was reduced to about 1/8 of the pumping laser pulse width. The effects of the DPSSL Q-switching frequency, the driving current, and the cavity loss on the dye laser pulse width were investigated by using a simple plane-parallel cavity. From the measured pulse width of the dye laser as a function of the reflectivity of the dye laser output coupler, we found that the cavity loss due to the frequency selection elements and the output coupler should be less than 70 % in order to avoid a drast...

  4. Single-mode pulsed dye laser pumped by using a diode-pumped Nd:YAG laser with a long pulse width

    International Nuclear Information System (INIS)

    Yi, Jong Hoon; Kim, Jin Tae; Moon, Hee Jong; Rho, Si Pyo; Han, Jae Min; Rhee, Yong Joo; Lee, Jong Min

    1999-01-01

    The lasing characteristics of a single-mode dye laser pumped by using a diode-pumped solid-state laser (DPSSL) with a high repetition rate is described. A 45-mm-long Nd:YAG rod was pumped by three CW diode arrays and it was acousto-optically Q-switched. A KTP crystal was used for intracavity frequency doubling. The pulse width of the laser ranged from 90 ns to 200 ns, depending on the diode current and the Q-switching frequency. The single-mode dye laser had a grazing incidence configuration. The pulse width of the dye laser was reduced to about 1/8 of the pumping laser pulse width. The effects of the DPSSL Q-switching frequency, the driving current, and the cavity loss on the dye laser pulse width were investigated by using a simple plane-parallel cavity. From the measured pulse width of the dye laser as a function of the reflectivity of the dye laser output coupler, we found that the cavity loss due to the frequency selection elements and the output coupler should be less than 70 % in order to avoid a drastically reduced pulse width

  5. Detecting cm-scale hot spot over 24-km-long single-mode fiber by using differential pulse pair BOTDA based on double-peak spectrum.

    Science.gov (United States)

    Diakaridia, Sanogo; Pan, Yue; Xu, Pengbai; Zhou, Dengwang; Wang, Benzhang; Teng, Lei; Lu, Zhiwei; Ba, Dexin; Dong, Yongkang

    2017-07-24

    In distributed Brillouin optical fiber sensor when the length of the perturbation to be detected is much smaller than the spatial resolution that is defined by the pulse width, the measured Brillouin gain spectrum (BGS) experiences two or multiple peaks. In this work, we propose and demonstrate a technique using differential pulse pair Brillouin optical time-domain analysis (DPP-BOTDA) based on double-peak BGS to enhance small-scale events detection capability, where two types of single mode fiber (main fiber and secondary fiber) with 116 MHz Brillouin frequency shift (BFS) difference have been used. We have realized detection of a 5-cm hot spot at the far end of 24-km single mode fiber by employing a 50-cm spatial resolution DPP-BOTDA with only 1GS/s sampling rate (corresponding to 10 cm/point). The BFS at the far end of 24-km sensing fiber has been measured with 0.54 MHz standard deviation which corresponds to a 0.5°C temperature accuracy. This technique is simple and cost effective because it is implemented using the similar experimental setup of the standard BOTDA, however, it should be noted that the consecutive small-scale events have to be separated by a minimum length corresponding to the spatial resolution defined by the pulse width difference.

  6. Richtmyer–Meshkov instability of a thermal interface in a two-fluid plasma

    KAUST Repository

    Bond, D.

    2017-11-03

    We computationally investigate the Richtmyer–Meshkov instability of a density interface with a single-mode perturbation in a two-fluid, ion–electron plasma with no initial magnetic field. Self-generated magnetic fields arise subsequently. We study the case where the density jump across the initial interface is due to a thermal discontinuity, and select plasma parameters for which two-fluid plasma effects are expected to be significant in order to elucidate how they alter the instability. The instability is driven via a Riemann problem generated precursor electron shock that impacts the density interface ahead of the ion shock. The resultant charge separation and motion generates electromagnetic fields that cause the electron shock to degenerate and periodically accelerate the electron and ion interfaces, driving Rayleigh–Taylor instability. This generates small-scale structures and substantially increases interfacial growth over the hydrodynamic case.

  7. Origin, evolution and geothermometry of the thermal waters in the Gölemezli Geothermal Field, Denizli Basin (SW Anatolia, Turkey)

    Science.gov (United States)

    Alçiçek, Hülya; Bülbül, Ali; Brogi, Andrea; Liotta, Domenico; Ruggieri, Giovanni; Capezzuoli, Enrico; Meccheri, Marco; Yavuzer, İbrahim; Alçiçek, Mehmet Cihat

    2018-01-01

    The Gölemezli Geothermal Field (GGF) is one of the best known geothermal fields in western Anatolia (Turkey). The exploited fluids are of meteoric origin, mixed with deep magmatic fluids, which interacted with the metamorphic rocks of the Menderes Massif. The geothermal fluids are channeled along Quaternary faults belonging to the main normal faults system delimiting the northern side of the Denizli Basin and their associated transfer zones. In this study, hydrochemical and isotopic analyses of the thermal and cold waters allow us to determine water-rock interactions, fluid paths and mixing processes. Two groups of thermal waters have been distinguished: (i) Group 1A, comprising Na-SO4 type and Ca-SO4 type and (ii) Group 1B, only consisting Ca-HCO3 type waters. Differently, two groups were recognized in the cold waters: (i) Group 2A, corresponding to Ca-HCO3 type and (ii) Group 2B, including Mg-HCO3 type. Their geochemical characteristics indicate interactions with the Paleozoic metamorphic rocks of the Menderes Massif and with the Neogene lacustrine sedimentary rocks. Dissolution of host rock and ion-exchange reactions modify thermal water composition in the reservoir of the GGF. High correlation in some ionic ratios and high concentrations of some minor elements suggest an enhanced water-rock interaction. None of the thermal waters has been reached a complete chemical re-equilibrium, possibly as a result of mixing with cold water during their pathways. Geothermal reservoir temperatures are calculated in the range of 130-210°C for the Gölemezli field. Very negative δ18O and δ2H isotopic ratios are respectively between -8.37 and -8.13‰ and -61.09 and -59.34‰ for the SO4-rich thermal waters, and ca. - 8.40 and -8.32‰ and - 57.80 and -57.41‰ for the HCO3-rich thermal waters. Low tritium (link existing between fractures and fluid convection in the extensional settings. In this view, the GGF is a very good example of geothermal field associated to active

  8. Thermal remote sensing approach combined with field spectroscopy for detecting underground structures intended for defence and security purposes in Cyprus

    Science.gov (United States)

    Melillos, George; Themistocleous, Kyriacos; Hadjimitsis, Diofantos G.

    2018-04-01

    The purpose of this paper is to present the results obtained from unmanned aerial vehicle (UAV) using multispectral with thermal imaging sensors and field spectroscopy campaigns for detecting underground structures. Airborne thermal prospecting is based on the principle that there is a fundamental difference between the thermal characteristics of underground structures and the environment in which they are structure. This study aims to combine the flexibility and low cost of using an airborne drone with the accuracy of the registration of a thermal digital camera. This combination allows the use of thermal prospection for underground structures detection at low altitude with high-resolution information. In addition vegetation indices such as the Normalized Difference Vegetation Index (NDVI) and Simple Ratio (SR), were utilized for the development of a vegetation index-based procedure aiming at the detection of underground military structures by using existing vegetation indices or other in-band algorithms. The measurements were taken at the following test areas such as: (a) vegetation area covered with the vegetation (barley), in the presence of an underground military structure (b) vegetation area covered with the vegetation (barley), in the absence of an underground military structure. It is important to highlight that this research is undertaken at the ERATOSTHENES Research Centre which received funding to be transformed to an EXcellence Research Centre for Earth SurveiLlance and Space-Based MonItoring Of the EnviRonment (Excelsior) from the HORIZON 2020 Widespread-04-2017: Teaming Phase 1(Grant agreement no: 763643).

  9. Numerical analysis of thermal process in the near field around vertical disposal of high-level radioactive waste

    Directory of Open Access Journals (Sweden)

    H.G. Zhao

    2014-02-01

    Full Text Available For deep geological disposal of high-level radioactive waste (HLW in granite, the temperature on the HLW canisters is commonly designed to be lower than 100 °C. This criterion dictates the dimension of the repository. Based on the concept of HLW disposal in vertical boreholes, thermal process in the near field (host rock and buffer surrounding HLW canisters has been simulated by using different methods. The results are drawn as follows: (a the initial heat power of HLW canisters is the most important and sensitive parameter for evolution of temperature field; (b the thermal properties and variations of the host rock, the engineered buffer, and possible gaps between canister and buffer and host rock are the additional key factors governing the heat transformation; (c the gaps width and the filling by water or air determine the temperature offsets between them.

  10. Modeling of thermal evolution of near field area around single pit mode nuclear waste canister disposal in soft rocks

    International Nuclear Information System (INIS)

    Bajpai, R.K.; Verma, A.K.; Maheshwar, Sachin

    2016-01-01

    Soft rocks like argillites/shales are under consideration worldwide as host rock for geological disposal of vitrified as well as spent fuel nuclear waste. The near field around disposed waste canister at 400-500m depth witnesses a complex heat field evolution due to varying thermal characteristics of rocks, coupling with hydraulic processes and varying intensity of heat flux from the canister. Smooth heat dissipation across the rock is desirable to avoid buildup of temperature beyond design limit (100 °C) and resultant micro fracturing due to thermal stresses in the rocks and intervening buffer clay layers. This also causes enhancement of hydraulic conductivity of the rocks, radionuclide transport and greater groundwater ingress towards the canister. Hence heat evolution modeling constitutes an important part of safety assessment of geological disposal facilities

  11. Impact of different improvement measures on the thermal performance of a solar collector field for district heating

    DEFF Research Database (Denmark)

    Bava, Federico; Furbo, Simon

    2018-01-01

    The paper describes the impact of different measures to improve the thermal performance of a solar heating plant for district heating applications. The impact of the different measures was evaluated through a validated TRNSYS-Matlab model. The model included details such as effect of the flow...... temperature of the collector field, control strategy based on weather forecast and use of different heat transfer fluids. The results showed that accurate input to the control strategy improved the yearly energy output of the plant by about 3%. If accurate input is not technically or economically feasible...... regime in the absorber pipes on the collector efficiency, flow distribution in the collector field, thermal capacity of the pipes and shadows from row to row. The improvement measures included variation of the operating temperatures, accurate input to the control strategy, feedback control on the outlet...

  12. Laser cutting of triangular geometry into 2024 aluminum alloy: Influence of triangle size on thermal stress field

    Energy Technology Data Exchange (ETDEWEB)

    Yilbas, Bekir Sami; Akhtar, Syed Sohail [King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Keles, Omer; Boran, Kurtulus [Gazi University, Ankara (Turkmenistan)

    2015-08-15

    Laser cutting of a triangular geometry into aluminum 2024 alloy is carried out. Thermal stress field in the cutting section is predicted using the finite element code ABAQUS. Surface temperature predictions are validated through the thermocouple data. Morphological changes in the cut section are examined incorporating optical and electron scanning microscopes. The effects of the size of the triangular geometry on thermal stress field are also examined. It is found that surface temperature predictions agree well with thermocouple data. von Mises stress remains high in the region close to the corners of the triangular geometry, which is more pronounced for the small size triangle. This behavior is associated with the occurrence of the high cooling rates in this region. Laser cut edges are free from large scale sideways burning and large size burr attachments. However, some locally scattered dross attachments are observed at the kerf exit.

  13. Preparation of polyurethane/montmorillonite nanocomposites by solution: characterization using low-field NMR and study of thermal stability

    International Nuclear Information System (INIS)

    Silva, Marcos Anacleto da; Tavares, Maria Ines B.

    2009-01-01

    Polyurethanes (PU) are important and versatile class of polymer materials, especially because of their desirable properties, such as high abrasion resistance, tear strength, excellent shock absorption, flexibility and elasticity. However, there also exist some disadvantages, for example, low thermal stability and barrier properties. To overcome the disadvantages, research on novel polyurethane/clay nanocomposites has been carried out. The investigation of the structure of polyurethane/clay nanocomposites has been mostly done by X-ray diffraction (XRD) and transmission electron microscopy (TEM). In this work, PU/clay films were prepared by solution, and the obtained nanocomposites were characterized by XRD and low-field nuclear magnetic resonance (NMR). Low field NMR measurements were able to provide important information on molecular dynamics of the polymeric nanocomposites PU/OMMT. In addition, they also confirmed the results obtained by XRD. The thermal stability was determined by thermogravimetric analysis (TGA). (author)

  14. Field induced decrystallization of silicon: Evidence of a microwave non-thermal effect

    Science.gov (United States)

    Nozariasbmarz, Amin; Dsouza, Kelvin; Vashaee, Daryoosh

    2018-02-01

    It is rather strange and not fully understood that some materials decrystallize when exposed to microwave radiation, and it is still debatable if such a transformation is a thermal or non-thermal effect. We hereby report experimental evidences that weight the latter effect. First, a single crystal silicon wafer exposed to microwaves showed strong decrystallization at high temperature. Second, when some areas of the wafer were masked with metal coating, only the exposed areas underwent decrystallization. Transmission electron microscopy analysis, x-ray diffraction data, and thermal conductivity measurements all indicated strong decrystallization, which occurred in the bulk of the material and was not a surface effect. These observations favor the existence of a non-thermal microwave effect.

  15. Quality stability and sensory attributes of apple juice processed by thermosonication, pulsed electric field and thermal processing.

    Science.gov (United States)

    Sulaiman, Alifdalino; Farid, Mohammed; Silva, Filipa Vm

    2017-04-01

    Worldwide, apple juice is the second most popular juice, after orange juice. It is susceptible to enzymatic browning spoilage by polyphenoloxidase, an endogenous enzyme. In this study, Royal Gala apple juice was treated by thermosonication (TS: 1.3 W/mL, 58 ℃, 10 min), pulsed electric field (PEF: 24.8 kV/cm, 60 pulses, 169 µs treatment time, 53.8 ℃) and heat (75 ℃, 20 min) and stored at 3.0 ℃ and 20.0 ℃ for 30 days. A sensory analysis was carried out after processing. The polyphenoloxidase activity, antioxidant activity and total color difference of the apple juice were determined before and after processing and during storage. The sensory analysis revealed that thermosonication and pulsed electric field juices tasted differently from the thermally treated juice. Apart from the pulsed electric field apple juice stored at room temperature, the processed juice was stable during storage, since the pH and soluble solids remained constant and fermentation was not observed. Polyphenoloxidase did not reactivate during storage. Along storage, the juices' antioxidant activity decreased and total color difference increased (up to 6.8). While the antioxidant activity increased from 86 to 103% with thermosonication and was retained after pulsed electric field, thermal processing reduced it to 67%. The processing increased the total color difference slightly. No differences in the total color difference of the juices processed by the three methods were registered after storage. Thermosonication and pulsed electric field could possibly be a better alternative to thermal preservation of apple juice, but refrigerated storage is recommended for pulsed electric field apple juice.

  16. Thionyl chloride assisted functionalization of amorphous carbon nanotubes: A better field emitter and stable nanofluid with better thermal conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, S.K.; Jha, A. [School of Materials Science and Nanotechnology, Jadavpur University, Kolkata 700 032 (India); Chattopadhyay, K.K., E-mail: kalyan_chattopadhyay@yahoo.com [Thin Film & Nanoscience Laboratory, Department of Physics, Jadavpur University, Kolkata 700 032 (India); School of Materials Science and Nanotechnology, Jadavpur University, Kolkata 700 032 (India)

    2015-06-15

    Highlights: • Thionyl chloride assisted functionalization of amorphous carbon nanotubes (a-CNTs). • Improved dispersion enhanced thermal conductivity of engine oil. • Again f-a-CNTs showed enhanced field emission property compared to pure a-CNTs. - Abstract: Amorphous carbon nanotubes (a-CNTs) were synthesized at low temperature in open atmosphere and further functionalized by treating them in thionyl chloride added stearic acid-dichloro methane solution. The as prepared functionalized a-CNTs (f-a-CNTs) were characterized by Raman spectroscopy, Fourier transformed infrared spectroscopy, X-ray photoelectron spectroscopy, transmission and scanning electron microscopy. The nanofluid was prepared by dispersing f-a-CNTs in engine oil using ultrasonic treatment. The effective thermal conductivity of as prepared nanofluid was investigated at different loading (volume fraction of f-a-CNTs). Obtained experimental data of thermal conductivity were compared with the predicted values, calculated using existing theoretical models. Stability of the nanofluid was tested by means of zeta potential measurement to optimize the loading. The as prepared f-a-CNTs sample also showed improved field emission result as compared to pristine a-CNTs. Dependence of field emission behavior on inter electrode distance was investigated too.

  17. Kinetic Monte Carlo simulations for transient thermal fields: Computational methodology and application to the submicrosecond laser processes in implanted silicon.

    Science.gov (United States)

    Fisicaro, G; Pelaz, L; Lopez, P; La Magna, A

    2012-09-01

    Pulsed laser irradiation of damaged solids promotes ultrafast nonequilibrium kinetics, on the submicrosecond scale, leading to microscopic modifications of the material state. Reliable theoretical predictions of this evolution can be achieved only by simulating particle interactions in the presence of large and transient gradients of the thermal field. We propose a kinetic Monte Carlo (KMC) method for the simulation of damaged systems in the extremely far-from-equilibrium conditions caused by the laser irradiation. The reference systems are nonideal crystals containing point defect excesses, an order of magnitude larger than the equilibrium density, due to a preirradiation ion implantation process. The thermal and, eventual, melting problem is solved within the phase-field methodology, and the numerical solutions for the space- and time-dependent thermal field were then dynamically coupled to the KMC code. The formalism, implementation, and related tests of our computational code are discussed in detail. As an application example we analyze the evolution of the defect system caused by P ion implantation in Si under nanosecond pulsed irradiation. The simulation results suggest a significant annihilation of the implantation damage which can be well controlled by the laser fluence.

  18. Reversal mechanisms and interactions in magnetic systems: coercivity versus switching field and thermally assisted demagnetization

    Directory of Open Access Journals (Sweden)

    Cebollada, F.

    2005-06-01

    Full Text Available In this paper we present a comparative analysis of the magnetic interactions and reversal mechanisms of two different systems: NdFeB-type alloys with grain sizes in the single domain range and Fe-SiO2 nanocomposites with Fe concentrations above and below the percolation threshold. We evidence that the use of the coercivity as the main parameter to analyse them might be misleading due to the convolution of both reversible and irreversible magnetization variations. We show that the switching field and thermally assisted demagnetization allow a better understanding of these mechanisms since they involve just irreversible magnetization changes. Specifically, the experimental analysis of the coercivity adquisition process for the NdFeB-type system suggests that the magnetization reversal is nucleated at the spin misalignments present due to intergranular exchange interactions. On the other hand, the study of the magnetic viscosity and of the isothermal remanent magnetization (IRM and direct field demagnetization (DCD remanence curves indicates that the dipolar interactions are responsible for the propagation of the switching started at individual particles.

    En este artículo presentamos un análisis comparativo de la influencia de la microestructura a través de las interacciones magnéticas en los mecanismos de inversión de la magnetización en dos sistemas diferentes: aleaciones tipo NdFeB con tamaños de grano en el rango de monodominio y nanocompuestos de Fe-SiO2 con concentraciones de Fe tanto por encima como por debajo del umbral de percolación. Ponemos de manifiesto que el uso del campo coercitivo como parámetro de análisis puede llevar a equívocos debido a la coexistencia de variaciones reversibles e irreversibles de la magnetización. También mostramos que el campo de conmutación y la desimanación térmicamente asistida permiten una mejor comprensión de dichos mecanismos ya que reflejan exclusivamente cambios irreversibles de

  19. Antimicrobial effect and shelf-life extension by combined thermal and pulsed electric field treatment of milk.

    Science.gov (United States)

    Walkling-Ribeiro, M; Noci, F; Cronin, D A; Lyng, J G; Morgan, D J

    2009-01-01

    The impact of a combined hurdle treatment of heat and pulsed electric fields (PEF) was studied on native microbiota used for the inoculation of low-fat ultra-high temperature (UHT) milk and whole raw milk. Microbiological shelf-life of the latter following hurdle treatment or thermal pasteurization was also investigated. UHT milk was preheated to 30 degrees C, 40 degrees C or 50 degrees C over a 60-s period, pulsed for 50 micros or 60 micros at a field strength of 40 kV cm(-1) or for 33 micros at 50 kV cm(-1). Heat and PEF reduced the microbial count by a maximum of 6.4 log in UHT milk (50 degrees C; 50 kV cm(-1), 33 micros) compared to 6.0 log (P > or = 0.05) obtained by thermal pasteurization (26 s, 72 degrees C). When raw milk was treated with a combination of hurdles (50 degrees C; 40 kV cm(-1), 60 micros) a 6.0 log inactivation of microbiota was achieved and microbiological milk shelf-life was extended to 21 days under refrigeration (4 degrees C) vs 14 days in thermally pasteurized milk. Native microbiota was decreased by 6.7 log following conventional pasteurization. The findings suggest that heat and PEF achieved similar inactivation of native microbiota in milk and longer stabilization of microbiological shelf-life than thermal pasteurization. A hurdle approach of heat and PEF could represent a valid milk processing alternative to conventional pasteurization. Hurdle treatment might also preserve native milk quality better due to less thermal exposure.

  20. Near-field thermal upconversion and energy transfer through a Kerr medium.

    Science.gov (United States)

    Khandekar, Chinmay; Rodriguez, Alejandro W

    2017-09-18

    We present an approach for achieving large Kerr χ (3) -mediated thermal energy transfer at the nanoscale that exploits a general coupled-mode description of triply resonant, four-wave mixing processes. We analyze the efficiency of thermal upconversion and energy transfer from mid- to near-infrared wavelengths in planar geometries involving two slabs supporting far-apart surface plasmon polaritons and separated by a nonlinear χ (3) medium that is irradiated by externally incident light. We study multiple geometric and material configurations and different classes of intervening mediums-either bulk or nanostructured lattices of nanoparticles embedded in nonlinear materials-designed to resonantly enhance the interaction of the incident light with thermal slab resonances. We find that even when the entire system is in thermodynamic equilibrium (at room temperature) and under typical drive intensities ~ W/μm 2 , the resulting upconversion rates can approach and even exceed thermal flux rates achieved in typical symmetric and non-equilibrium configurations of vacuum-separated slabs. The proposed nonlinear scheme could potentially be exploited to achieve thermal cooling and refrigeration at the nanoscale, and to actively control heat transfer between materials with dramatically different resonant responses.

  1. Uncertainty Evaluations of the CRCS In-orbit Field Radiometric Calibration Methods for Thermal Infrared Channels of FENGYUN Meteorological Satellites

    Science.gov (United States)

    Zhang, Y.; Rong, Z.; Min, M.; Hao, X.; Yang, H.

    2017-12-01

    Meteorological satellites have become an irreplaceable weather and ocean-observing tool in China. These satellites are used to monitor natural disasters and improve the efficiency of many sectors of Chinese national economy. It is impossible to ignore the space-derived data in the fields of meteorology, hydrology, and agriculture, as well as disaster monitoring in China, a large agricultural country. For this reason, China is making a sustained effort to build and enhance its meteorological observing system and application system. The first Chinese polar-orbiting weather satellite was launched in 1988. Since then China has launched 14 meteorological satellites, 7 of which are sun synchronous and 7 of which are geostationary satellites; China will continue its two types of meteorological satellite programs. In order to achieve the in-orbit absolute radiometric calibration of the operational meteorological satellites' thermal infrared channels, China radiometric calibration sites (CRCS) established a set of in-orbit field absolute radiometric calibration methods (FCM) for thermal infrared channels (TIR) and the uncertainty of this method was evaluated and analyzed based on TERRA/AQUA MODIS observations. Comparisons between the MODIS at pupil brightness temperatures (BTs) and the simulated BTs at the top of atmosphere using radiative transfer model (RTM) based on field measurements showed that the accuracy of the current in-orbit field absolute radiometric calibration methods was better than 1.00K (@300K, K=1) in thermal infrared channels. Therefore, the current CRCS field calibration method for TIR channels applied to Chinese metrological satellites was with favorable calibration accuracy: for 10.5-11.5µm channel was better than 0.75K (@300K, K=1) and for 11.5-12.5µm channel was better than 0.85K (@300K, K=1).

  2. Hydrochemistry and groundwater system of the Zerka Ma'in-Zara thermal field, Jordan

    Science.gov (United States)

    Rimawi, Omar; Salameh, Elias

    1988-03-01

    A groundwater flow model through the different geological successions from the Upper Cretaceous through the Lower Cretaceous Sandstone and older units is presented in this paper. The model is supported by the hydrochemical evolution of water types from the recharge areas in the highlands to discharge sites of thermal water at the slopes overlooking the Dead Sea. The thermal water discharged in the Zerka Ma'in-Zara areas consists of three end members mixed in different ratios with a component of old (many thousands of years) thermal water undersaturated in carbonate minerals and containing hundreds of milligrams per liter of free CO 2. The release of CO 2 gas upon discharge renders the water oversaturated with respect to carbonate minerals which results in aragonite precipitation. The elevated temperature of the water in the reservoir (73-82°C) is attributed to the presence of a heat-storing layer topping the aquifer.

  3. Toward constructing a time-series of geomagnetic field variations from thermal remanence in slowly cooled igneous rocks

    Science.gov (United States)

    Burns, Z.; Gee, J. S.

    2017-12-01

    Analysis of paleomagnetic data can not only help us to understand the behavior of the ancient magnetic field but may also further our understanding of the current field, as well as of the mechanisms and constraints of the geodynamo and geomagnetic reversals. A question of particular interest is the possible relationship between reversal frequency and geomagnetic field intensity. Some research appears to indicate a correlation between low intensity and high reversal frequency, seeming to support the theory that low field intensity is what makes reversals possible. In order to study this correlation, we obtained several hundred samples from the 182 Ma Dufek Massif, in Antarctica. This intrusion was cooled slowly, at depth, during the high reversal frequency era of the early Jurassic, and most of our samples record multiple polarity intervals. This, combined with their particularly homogeneous magnetic characteristics, makes them ideally suited for recovering a record of geomagnetic field variations. On approximately 300 samples from the lower portion of the intrusion, we performed step-wise thermal demagnetization of the natural remanent magnetization (NRM), followed by thermal demagnetization of a laboratory thermoremance (TRM), imparted as partial TRMs in three orthogonal directions to assess the reliability of the remanence. These two sets of measurements can tell us about the amount and direction of magnetization acquired at each temperature step and the sample's capacity to acquire a remanence. Corrected for anisotropy, the ratio of the NRM/TRM values at each step multiplied by the value of the lab field can give us an estimate of the paleofield intensity. When convolved with a thermal cooling model for the intrusion, this yields a model of the time-varying ancient field during the intrusion's cooling period. Initial analysis of our data shows average field values of around 20 µT and a minimum of four reversals. The average at this high-latitude site is lower

  4. Breast cancer diagnosis by thermal imaging in the fields of medical and artificial intelligence sciences: review article

    Directory of Open Access Journals (Sweden)

    Hossein Ghayoumi Zadeh

    2016-09-01

    Full Text Available Breast cancer is the most common cancer in women and one of the leading of death among them. The high and increasing incidence of the disease and its difficult treatment specifically in advanced stages, imposes hard situations for different countries’ health systems. Body temperature is a natural criteria for the diagnosis of diseases. In recent decades extensive research has been conducted to increase the use of thermal cameras and obtain a close relationship between heat and temperature of the skin's physiology. Thermal imaging (thermography applies infrared method which is fast, non-invasive, non-contact and flexibile to monitor the temperature of the human body. This paper investigates highly diversified studies implemented before and after the year 2000. And it emphasizes mostly on the newely published articles including: performance and evaluation of thermal imaging, the various aspects of imaging as well as The available technology in this field and its disadvantages in the diagnosis of breast cancer. Thermal imaging has been adopted by researchers in the fields of medicine and biomedical engineering for the diagnosis of breast cancer. With the advent of modern infrared cameras, data acquisition and processing techniques, it is now possible to have real time high resolution thermographic images, which is likely to surge further research in this field.  Thermography does not provide information on the structures of the breast morphology, but it provides performance information of temperature and breast tissue vessels. It is assumed that the functional changes occured before the start of the structural changes which is the result of disease or cancer. These days, thermal imaging method has not been established as an applicative method for screening or diagnosing purposes in academic centers. But there are different centers that adopt this method for the diognosis and examining purposes. Thermal imaging is an effective method which is

  5. Stable single-mode distributed feedback quantum cascade lasers at λ ∼ 4.25 μm with low power consumption

    Science.gov (United States)

    Jia, Zhiwei; Wang, Lijun; Zhang, Jinchuan; Liu, Fengqi; Zhuo, Ning; Zhai, Shenqiang; Liu, Junqi; Wang, Zhanguo

    2016-10-01

    Short-wavelength (4.25 μm) distributed-feedback quantum cascade laser operating in continuous wave (cw) mode at room temperature with low power consumption was presented. Stable single-mode operation with a side-mode-suppression-ratio above 25 dB was maintained for the whole measured current and temperature range by enlarging gain difference and strong grating coupling. Because of the strong coupling, very low threshold current and power consumption were achieved. For a device of 9-μm-wide and 2-mm-long, the cw threshold current and power consumption at 293 K were as low as 126 mA and 1.45 W, respectively. All results above were from the device without using buried heterostructure geometry.

  6. Single-mode molecular beam epitaxy grown PbEuSeTe/PbTe buried-heterostructure diode lasers for CO2 high-resolution spectroscopy

    International Nuclear Information System (INIS)

    Feit, Z.; Kostyk, D.; Woods, R.J.; Mak, P.

    1991-01-01

    Buried-heterostructure tunable PbEuSeTe/PbTe lasers were fabricated using a two-stage molecular beam epitaxy growth procedure. Improvements in the processing technique yielded lasers that show performance characteristics significantly better than those reported previously. A continuous wave (cw) operating temperature of 203 K was realized, which is the highest cw operating temperature ever reported for lead-chalcogenides diode lasers. This laser exhibited exceptionally low-threshold currents of 1.4 mA at 90 K and 43 mA at 160 K with single-mode operation for injection currents up to 30I th and 0.18 mW power at 100 K. The usefulness of the laser, when operating cw at 200 K, was demonstrated by the ability to perform high-resolution spectroscopy of a low-pressure CO 2 gas sample

  7. Low-loss polarization-maintaining fusion splicing of single-mode fibers and hollow-core photonic crystal fibers, relevant for monolithic fiber laser pulse compression

    DEFF Research Database (Denmark)

    Kristensen, Jesper Toft; Houmann, Andreas; Liu, Xiaomin

    2008-01-01

    of the splicing process. We also demonstrate that the higher splice loss compromises the PM properties of the splice. Our splicing technique was successfully applied to the realization of a low-loss, environmentally stable monolithic PM fiber laser pulse compressor, enabling direct end-of-the-fiber femtosecond......We report on highly reproducible low-loss fusion splicing of polarization-maintaining single-mode fibers (PM-SMFs) and hollow-core photonic crystal fibers (HC-PCFs). The PM-SMF-to-HC-PCF splices are characterized by the loss of 0.62 ± 0.24 dB, and polarization extinction ratio of 19 ± 0.68 d...... pulse delivery...

  8. VCSEL Transmission at 10 Gb/s for 20 km Single Mode Fiber WDM-PON without Dispersion Compensation or Injection Locking

    DEFF Research Database (Denmark)

    Gibbon, Timothy Braidwood; Prince, Kamau; Pham, Tien Thang

    2011-01-01

    how off-center wavelength filtering of the VCSEL spectrum at an array waveguide grating can be used to mitigate the effect of chirp and the dispersion penalty. Transmission at 10Gb/s VCSEL over 23.6 km of single mode fiber is experimentally demonstrated, with a dispersion penalty of only 2.9 d......B. Simulated results are also presented which show that off-center wavelength filtering can extend the 10 Gb/s network reach from 11.7 km to 25.8 km for a 4 dB dispersion penalty. This allows for cheap and simple dispersion mitigation in next generation VCSEL based optical access networks....

  9. Fabrication of Long Period Gratings by Periodically Removing the Coating of Cladding-Etched Single Mode Optical Fiber Towards Optical Fiber Sensor Development

    Directory of Open Access Journals (Sweden)

    Joaquin Ascorbe

    2018-06-01

    Full Text Available Here, we present a novel method to fabricate long period gratings using standard single mode optical fibers (SMF. These optical devices were fabricated in a three-step process, which consisted of etching the SMF, then coating it with a thin-film and, the final step, which involved removing sections of the coating periodically by laser ablation. Tin dioxide was chosen as the material for this study and it was sputtered using a pulsed DC sputtering system. Theoretical simulations were performed in order to select the appropriate parameters for the experiments. The responses of two different devices to different external refractive indices was studied, and the maximum sensitivity obtained was 6430 nm/RIU for external refractive indices ranging from 1.37 to 1.39.

  10. Fabrication of Long Period Gratings by Periodically Removing the Coating of Cladding-Etched Single Mode Optical Fiber Towards Optical Fiber Sensor Development.

    Science.gov (United States)

    Ascorbe, Joaquin; Corres, Jesus M; Del Villar, Ignacio; Matias, Ignacio R

    2018-06-07

    Here, we present a novel method to fabricate long period gratings using standard single mode optical fibers (SMF). These optical devices were fabricated in a three-step process, which consisted of etching the SMF, then coating it with a thin-film and, the final step, which involved removing sections of the coating periodically by laser ablation. Tin dioxide was chosen as the material for this study and it was sputtered using a pulsed DC sputtering system. Theoretical simulations were performed in order to select the appropriate parameters for the experiments. The responses of two different devices to different external refractive indices was studied, and the maximum sensitivity obtained was 6430 nm/RIU for external refractive indices ranging from 1.37 to 1.39.

  11. Differential modal delay measurements in a graded-index multimode fibre waveguide, using a single-mode fibre pro mode selection

    International Nuclear Information System (INIS)

    Sunak, H.R.D.; Soares, S.M.

    1981-01-01

    Differential model delay (DMD) measurements in graded-index multimode optical fibre waveguides, which are very promising for many types of communication system were carried out. These DMD measurements give a direct indication of the deviation of the refractive index profile, from the optimum value, at a given wavelength. For the first time, by using a single-mode fibre, a few guided modes in the graded-index fibre were selected, in two different ways: launching a few modes at the input end or selecting a few modes at the output end. By doing so important features of propagation in the fibre were revealed, especially the intermodal coupling that may exist. The importance of this determination of intermodal coupling or mode mixing, particularly when many fibres are joined together in a link, and the merits of DMD measurements in general and their importance for the production of high bandwidth graded-index fibres are discussed. (Author) [pt

  12. Parametric studies and evaluations of indoor thermal environment in wet season using a field survey and PMV-PPD method

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Shengxian [College of Physics and Electric Engineering, Qujing Normal University, Qujing 655011 (China); Key Laboratory of Advanced Technique and Preparation for Renewable Energy Materials, Ministry of Education, Yunnan Normal University, Kunming 650092 (China); Li, Ming [Key Laboratory of Advanced Technique and Preparation for Renewable Energy Materials, Ministry of Education, Yunnan Normal University, Kunming 650092 (China); Lin, Wenxian [Key Laboratory of Advanced Technique and Preparation for Renewable Energy Materials, Ministry of Education, Yunnan Normal University, Kunming 650092 (China); School of Engineering, James Cook University, Townsville, QLD 4811 (Australia); Sun, Yanlin [College of Physics and Electric Engineering, Qujing Normal University, Qujing 655011 (China)

    2010-06-15

    Fanger's PMV-PPD is the most famous thermal sensation indices but it is too complex to be applied in practice. To obtain simple and applicable correlations, taking Qujing of Yunnan province, China, as example, a wet season (six-month) field measurement was conducted in a naturally ventilated residential room. Based on collected data, PMV indices were calculated by using Newton's iterative method. It is shown that the PMV values approximately vary from -1.0 to +1.0 and the indoor thermal environment is basically comfortable. Relationships of the parameters (indoor and outdoor air temperatures, mean radiant temperature, PMV and PPD) and indoor air temperature gradients (vertical and horizontal) were also studied by means of the linear regression and the quadratic polynomial fit techniques. Numerous correlations with high relativities have been developed. Moreover, the vertical and horizontal air temperature gradients range from 0.1 K/m to 0.85 K/m and from -0.208 K/m to 0.063 K/m in wet season. It is convenient to use these results to evaluate and assess the indoor thermal environment under similar climatic conditions. The results of this work enrich and develop the basic theory of the indoor thermal environment design and control. (author)

  13. Intercomparison of personnel dosimetry for thermal neutron dose equivalent in neutron and gamma-ray mixed fields

    International Nuclear Information System (INIS)

    Ogawa, Yoshihiro

    1985-01-01

    In order to consider the problems concerned with personnel dosimetry using film badges and TLDs, an intercomparison of personnel dosimetry, especially dose equivalent responses of personnel dosimeters to thermal neutron, was carried out in five different neutron and gamma-ray mixed fields at KUR and UTR-KINKI from the practical point of view. For the estimation of thermal neutron dose equivalent, it may be concluded that each personnel dosimeter has good performances in the precision, that is, the standard deviations in the measured values by individual dosimeter were within 24 %, and the dose equivalent responses to thermal neutron were almost independent on cadmium ratio and gamma-ray contamination. However, the relative thermal neutron dose equivalent of individual dosimeter normalized to the ICRP recommended value varied considerably and a difference of about 4 times was observed among the dosimeters. From the results obtained, it is suggested that the standardization of calibration factors and procedures is required from the practical point of radiation protection and safety. (author)

  14. The demonstration of nonlinear analytic model for the strain field induced by thermal copper filled TSVs (through silicon via

    Directory of Open Access Journals (Sweden)

    M. H. Liao

    2013-08-01

    Full Text Available The thermo-elastic strain is induced by through silicon vias (TSV due to the difference of thermal expansion coefficients between the copper (∼18 ppm/ °C and silicon (∼2.8 ppm/ °C when the structure is exposed to a thermal ramp budget in the three dimensional integrated circuit (3DIC process. These thermal expansion stresses are high enough to introduce the delamination on the interfaces between the copper, silicon, and isolated dielectric. A compact analytic model for the strain field induced by different layouts of thermal copper filled TSVs with the linear superposition principle is found to have large errors due to the strong stress interaction between TSVs. In this work, a nonlinear stress analytic model with different TSV layouts is demonstrated by the finite element method and the analysis of the Mohr's circle. The characteristics of stress are also measured by the atomic force microscope-raman technique with nanometer level space resolution. The change of the electron mobility with the consideration of this nonlinear stress model for the strong interactions between TSVs is ∼2–6% smaller in comparison with those from the consideration of the linear stress superposition principle only.

  15. Thermal quantum and classical correlations in a two-qubit XX model in a nonuniform external magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Ali Saif M [Department of Physics, University of Amran, Amran (Yemen); Lari, Behzad; Joag, Pramod S, E-mail: alisaif73@gmail.co, E-mail: behzadlari1979@yahoo.co, E-mail: pramod@physics.unipune.ac.i [Department of Physics, University of Pune, Pune 411007 (India)

    2010-12-03

    We investigate how thermal quantum discord (QD) and classical correlations (CC) of a two-qubit one-dimensional XX Heisenberg chain in thermal equilibrium depend on the temperature of the bath as well as on nonuniform external magnetic fields applied to two qubits and varied separately. We show that the behavior of QD differs in many unexpected ways from the thermal entanglement (EOF). For the nonuniform case (B{sub 1} = -B{sub 2}), we find that QD and CC are equal for all values of (B{sub 1} = -B{sub 2}) and for different temperatures. We show that, in this case, the thermal states of the system belong to a class of mixed states and satisfy certain conditions under which QD and CC are equal. The specification of this class and the corresponding conditions are completely general and apply to any quantum system in a state in this class satisfying these conditions. We further find that the relative contributions of QD and CC can be controlled easily by changing the relative magnitudes of B{sub 1} and B{sub 2}. Finally, we connect our results with the monogamy relations between the EOF, CC and the QD of two qubits and the environment.

  16. Field induced phase transition in layered honeycomb spin system α-RuCl3 studied by thermal conductivity

    Science.gov (United States)

    Leahy, Ian; Bornstein, Alex; Choi, Kwang-Yong; Lee, Minhyea

    α -RuCl3, a quasi -two-dimensional honeycomb lattice is known to be a candidate material to realize the Heisenberg-Kitaev spin model of a highly anisotropic bond-dependent exchange interaction. We investigate in-plane thermal conductivity (κ) as a function of temperature (T) and in-plane applied field (H). At H = 0 , the onset of a strong increase in κ marks the spontaneous long range ordering temperature, Tc = 6 . 5 K , corresponding to ``zigzag'' antiferromagnetic ordering. A broad peak appearing below Tc in κ was found to be suppressed significantly as H increases up to ~ 7 T , implying the system undergoes a field-induced transition from ordered to a new spin-disordered state analogous to the transverse-field Ising model. Further increasing H above 7 . 1 T , the large field seems to begin polarizing spins thus increasing the phonon mean free path, resulting in a significant rise in κ. This tendency is clearly shown in the field dependence of κ below Tc, which has a pronounced minimum at Hmin = 7 . 1 T . We will discuss our scaling analysis to characterize this field-induced phase transition and compare to the transverse-field Ising spin system. Work at the University of Colorado was supported by the US DOE Basic Energy Sciences under Award No. DE-SC0006888.

  17. Thermal and magnetic properties of ternary mixed Ising nanoparticles with core–shell structure: Effective-field theory approach

    International Nuclear Information System (INIS)

    Kantar, Ersin; Keskin, Mustafa

    2014-01-01

    We propose a ternary Ising spins (1/2, 1, 3/2) model to investigate the thermal and magnetic properties of magnetic nanoparticles with core–shell structure within the framework of the effective-field theory with correlations. The center site of the core is occupied by σ=±1/2 spin, while those surrounding the center site are occupied by S=±1, 0 spins and the shell sites are occupied by m=±1/2,±3/2 spins. Thermal behaviors of the core and shell magnetizations, susceptibilities and internal energies as well as total magnetization are examined. In order to confirm the stability of the solutions we also investigate the free energy of the system. According to the values of Hamiltonian parameters, the system undergoes first- and second-order phase transitions. Phase diagrams are calculated and discussed in detail. We find that the system exhibits a tricritical point, reentrant and five different type (Q, P, R, S and W) of compensation behaviors that strongly depend on interaction parameters. The results are in good agreement with some experimental and theoretical results. - Highlights: • Thermal and magnetic properties of ternary Ising nanoparticles are studied. • Phase diagrams within the EFT with correlations are calculated and discussed. • The effects of the exchange interactions and crystal field have been studied. • Reentrant phenomena and compensation behaviors have been found

  18. Thermal and magnetic properties of ternary mixed Ising nanoparticles with core–shell structure: Effective-field theory approach

    Energy Technology Data Exchange (ETDEWEB)

    Kantar, Ersin [Department of Physics, Erciyes University, 38039 Kayseri (Turkey); Institute of Science, Erciyes University, 38039 Kayseri (Turkey); Keskin, Mustafa, E-mail: keskin@erciyes.edu.tr [Department of Physics, Erciyes University, 38039 Kayseri (Turkey)

    2014-01-15

    We propose a ternary Ising spins (1/2, 1, 3/2) model to investigate the thermal and magnetic properties of magnetic nanoparticles with core–shell structure within the framework of the effective-field theory with correlations. The center site of the core is occupied by σ=±1/2 spin, while those surrounding the center site are occupied by S=±1, 0 spins and the shell sites are occupied by m=±1/2,±3/2 spins. Thermal behaviors of the core and shell magnetizations, susceptibilities and internal energies as well as total magnetization are examined. In order to confirm the stability of the solutions we also investigate the free energy of the system. According to the values of Hamiltonian parameters, the system undergoes first- and second-order phase transitions. Phase diagrams are calculated and discussed in detail. We find that the system exhibits a tricritical point, reentrant and five different type (Q, P, R, S and W) of compensation behaviors that strongly depend on interaction parameters. The results are in good agreement with some experimental and theoretical results. - Highlights: • Thermal and magnetic properties of ternary Ising nanoparticles are studied. • Phase diagrams within the EFT with correlations are calculated and discussed. • The effects of the exchange interactions and crystal field have been studied. • Reentrant phenomena and compensation behaviors have been found.

  19. Evaluating the thermal and electrical performance of several uncovered PVT collectors with a field test

    NARCIS (Netherlands)

    de Keizer, C.; de Jong, M.; Mendes, T.; Katiyar, M.; Folkerts, W.; Rindt, C.C.M.; Zondag, H.A.

    Recently, there has been a lot of interest in PV thermal systems, which generate both heat and power. Within the WenSDak project, several companies and research institutes work together to (further) develop several uncovered PVT collectors. The outdoor performance of prototypes of these collectors

  20. Carbon nanotubes growing on rapid thermal annealed Ni and their application to a triode-type field emission device

    International Nuclear Information System (INIS)

    Uh, Hyung Soo; Park, Sang Sik

    2006-01-01

    In this paper, we demonstrate a new triode-type field emitter arrays using carbon nanotubes (CNTs) as an electron emitter source. In the proposed structure, the gate electrode is located underneath the cathode electrode and the extractor electrode is surrounded by CNT emitters. CNTs were selectively grown on the patterned Ni catalyst layer by using plasma-enhanced chemical vapor deposition (PECVD). Vertically aligned CNTs were grown with gas mixture of acetylene and ammonia under external DC bias. Compared with a conventional under-gate structure, the proposed structure reduced the turn-on voltage by about 30%. In addition, with a view to controlling the density of CNTs, Ni catalyst thickness was varied and rapid thermal annealing (RTA) treatment was optionally adopted before CNT growth. With controlled Ni thickness and RTA condition, field emission efficiency was greatly improved by reducing the density of CNTs, which is due to the reduction of the electric field screening effect caused by dense CNTs

  1. Thermal coupling in low fields between the nuclear and electronic spins in Tm2+ doped CaF2

    International Nuclear Information System (INIS)

    Urbina, Cristian.

    1977-01-01

    It is shown that in a CaF 2 crystal doped with divalent thulium ions there is in low fields, a thermal coupling between the electron magnetic moments of Tm 2+ and the nuclear moments of 19 F. When these ones have been lowered down to temperature through dynamical high-field polarization and adiabatic demagnetization in succession the resulting polarisation of the formed ones can overstep their original polarization in high field. A trial is given to explain this Zeeman electronic energy cooling through nuclear Zeeman energy with invoking a thermal coupling between both systems through the spin-spin electronic interaction but no theoretical model is developed in view of a quantitative explanation of the dynamics of such a process. The magnetic resonance spectrum of Tm 2 + in low field is also investigated: an important shift and narrowing of the electron resonance line in low field are obtained when 19 F nuclei are very cold. This special spectral characters are explained as due to magnetic interactions between electronic impurities and the neighbouring 19 F nuclei and a theoretical model is developed (based on the local Weiss field approximation) which explains rather well the changes in the spectral shift as a function of the 19 F nucleus temperature. A second theoretical model has also been developed in view of a quantitative explanation of both the narrowing and shift of the spectrum, but its prediction disagree with the experimental results. It is shown that in low fieldsx it is possible to get rid of paramagnetic impurities after they have been reused as reducing agents for 19 F nucleus entropy populating at about 80%, a non magnetic metastable state with these impurities [fr

  2. Development of a ReaxFF reactive force field for ammonium nitrate and application to shock compression and thermal decomposition.

    Science.gov (United States)

    Shan, Tzu-Ray; van Duin, Adri C T; Thompson, Aidan P

    2014-02-27

    We have developed a new ReaxFF reactive force field parametrization for ammonium nitrate. Starting with an existing nitramine/TATB ReaxFF parametrization, we optimized it to reproduce electronic structure calculations for dissociation barriers, heats of formation, and crystal structure properties of ammonium nitrate phases. We have used it to predict the isothermal pressure-volume curve and the unreacted principal Hugoniot states. The predicted isothermal pressure-volume curve for phase IV solid ammonium nitrate agreed with electronic structure calculations and experimental data within 10% error for the considered range of compression. The predicted unreacted principal Hugoniot states were approximately 17% stiffer than experimental measurements. We then simulated thermal decomposition during heating to 2500 K. Thermal decomposition pathways agreed with experimental findings.

  3. Thermal convection in a toroidal duct of a liquid metal blanket. Part I. Effect of poloidal magnetic field

    International Nuclear Information System (INIS)

    Zhang, Xuan; Zikanov, Oleg

    2017-01-01

    Highlights: • 2D convection flow develops with internal heating and strong axial magnetic field. • Poloidal magnetic field suppresses turbulence at high Hartmann number. • Flow structure is dominated by large-scale counter-rotation vortices. • Effective heat transfer is maintained by surviving convection structures. - Abstract: We explore the effect of poloidal magnetic field on the thermal convection flow in a toroidal duct of a generic liquid metal blanket. Non-uniform strong heating (the Grashof number up to 10 11 ) arising from the interaction of high-speed neutrons with the liquid breeder, and strong magnetic field (the Hartmann number up to 10 4 ) corresponding to the realistic reactor conditions are considered. The study continues our earlier work , where the problem was solved for a purely toroidal magnetic field and the convection was found to result in two-dimensional turbulence and strong mixing within the duct. Here, we find that the poloidal component of the magnetic field suppresses turbulence, reduces the flow's kinetic energy and high-amplitude temperature fluctuations, and, at high values of Hartmann number, leads to a steady-state flow. At the same time, the intense mixing by the surviving convection structures remains able to maintain effective heat transfer between the liquid metal and the walls.

  4. Measurement of volatile plant compounds in field ambient air by thermal desorption-gas chromatography-mass spectrometry.

    Science.gov (United States)

    Cai, Xiao-Ming; Xu, Xiu-Xiu; Bian, Lei; Luo, Zong-Xiu; Chen, Zong-Mao

    2015-12-01

    Determination of volatile plant compounds in field ambient air is important to understand chemical communication between plants and insects and will aid the development of semiochemicals from plants for pest control. In this study, a thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method was developed to measure ultra-trace levels of volatile plant compounds in field ambient air. The desorption parameters of TD, including sorbent tube material, tube desorption temperature, desorption time, and cold trap temperature, were selected and optimized. In GC-MS analysis, the selected ion monitoring mode was used for enhanced sensitivity and selectivity. This method was sufficiently sensitive to detect part-per-trillion levels of volatile plant compounds in field ambient air. Laboratory and field evaluation revealed that the method presented high precision and accuracy. Field studies indicated that the background odor of tea plantations contained some common volatile plant compounds, such as (Z)-3-hexenol, methyl salicylate, and (E)-ocimene, at concentrations ranging from 1 to 3400 ng m(-3). In addition, the background odor in summer was more abundant in quality and quantity than in autumn. Relative to previous methods, the TD-GC-MS method is more sensitive, permitting accurate qualitative and quantitative measurements of volatile plant compounds in field ambient air.

  5. Thermally radiative three-dimensional flow of Jeffrey nanofluid with internal heat generation and magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Shehzad, S.A., E-mail: ali_qau70@yahoo.com [Department of Mathematics, Comsats Institute of Information Technology, Sahiwal 57000 (Pakistan); Abdullah, Z. [Department of Mathematics, Comsats Institute of Information Technology, Sahiwal 57000 (Pakistan); Alsaedi, A. [Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science, King Abdulaziz University, P. O. Box 80257, Jeddah 21589 (Saudi Arabia); Abbasi, F.M. [Department of Mathematics, Comsats Institute of Information Technology, Islamabad 44000 (Pakistan); Hayat, T. [Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science, King Abdulaziz University, P. O. Box 80257, Jeddah 21589 (Saudi Arabia); Department of Mathematics, Quaid-I-Azam University 45320, Islamabad 44000 (Pakistan)

    2016-01-01

    This research work addresses the three-dimensional hydromagnetic flow of Jeffrey fluid with nanoparticles. Flow is generated by a bidirectional stretching surface. The effects of thermal radiation and internal heat generation are encountered in energy expressions. More realistic convective boundary conditions at the surface are employed instead of constant surface temperature and mass species conditions. Boundary layer assumptions lead to the governing non-linear mathematical model. Resulting equations through momentum, energy and mass species are made dimensionless using suitable variables. The solution expressions of dimensionless velocities, temperature and nanoparticle concentration have been computed for the convergent series solutions. The impacts of interesting parameters on the dimensionless quantities are displayed and interpreted. The values of physical quantities are computed and analyzed. - Highlights: • Three-dimensional hydromagnetic flow of Jeffrey nanofluid is considered. • Brownian motion and thermophoresis effects are encountered. • Heat transfer analysis is performed with thermal radiation. • Results are plotted and visualized.

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

    Indian Academy of Sciences (India)

    With this assumption, we obtain a general thermal instability criterion for magne- tized thin disks, i.e.,. = 2 − 5βgas − 4(1 + n)βmag − 6 fadv. + 8 fadvβgas + (8 + 4n) fadvβmag > 0, where βgas, βmag and fadv are the ratio of gas pressure to total pressure, the ratio of magnetic pressure to total pressure, and the advection factor ...

  7. A field study on thermal comfort in an Italian hospital considering differences in gender and age.

    Science.gov (United States)

    Del Ferraro, S; Iavicoli, S; Russo, S; Molinaro, V

    2015-09-01

    The hospital is a thermal environment where comfort must be calibrated by taking into account two different groups of people, that is, patients and medical staff. The study involves 30 patients and 19 medical staff with a view to verifying if Predicted Mean Vote (PMV) index can accurately predict thermal sensations of both groups also taking into account any potential effects of age and gender. The methodology adopted is based on the comparison between PMV values (calculated according to ISO 7730 after having collected environmental data and estimated personal parameters) and perceptual judgments (Actual Mean Vote, AMV), expressed by the subjects interviewed. Different statistical analyses show that PMV model finds his best correlation with AMV values in a sample of male medical staff under 65 years of age. It has been observed that gender and age are factors that must be taken into account in the assessment of thermal comfort in the hospital due to very weak correlation between AMV and PMV values. Copyright © 2015 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  8. Thermal and ghost reflection modeling for a 180-deg. field-of-view long-wave infrared lens

    Science.gov (United States)

    Shi, Weimin; Couture, Michael E.

    2001-03-01

    Optics 1, Inc. has successfully designed and developed a 180 degree(s) field of view long wave infrared lens for USAF/AFRL under SBIR phase I and II funded projects in support of the multi-national Programmable Integrated Ordinance Suite (PIOS) program. In this paper, a procedure is presented on how to evaluate image degradation caused by asymmetric aerodynamic dome heating. In addition, a thermal gradient model is proposed to evaluate degradation caused by axial temperature gradient throughout the entire PIOS lens. Finally, a ghost reflection analysis is demonstrated with non-sequential model.

  9. New insight into $nd\\rightarrow$ $^3H\\gamma$ process at thermal energy with pionless effective field theory

    OpenAIRE

    Arani, M. Moeini; Nematollahi, H.; Mahboubi, N.; Bayegan, S.

    2014-01-01

    We take a new look at the neutron radiative capture by a deuteron at thermal energy with the pionless effective field theory (EFT($\\pi\\!\\!\\!/$)) approach. We present in detail the calculation of $nd\\rightarrow$ $^3H\\gamma$ amplitudes for incoming doublet and quartet channels leading to the formation of a triton fully in the projection method based on the cluster-configuration space approach. In the present work, we consider all possible one-body and two-body photon interaction diagrams. In fa...

  10. Transparent thermal insulation - new developments in the field of building technology?; Transparente Waermedaemmung - neue Trends in der Gebaeudetechnik?

    Energy Technology Data Exchange (ETDEWEB)

    Bieler, P.

    1995-12-31

    In chapter 10 of the anthology about building control transparent thermal insulation is described as a possible new trend in the field of building technology. An answer is given to the question to which extent facades can be applied as technical building equipment. Furthermore the passive use of solar energy is discussed and the measuring results of a test cell building are presented. (BWI) [Deutsch] Kapitel 10 des Sammelbandes ueber Building Control stellt die transparente Waermedaemmung als moeglichen neuen Trend der Gebaeudetechnik vor. In diesem Zusammenhang wird die Frage aufgeworfen, inwieweit Fassaden als Technische Gebaeudeausruestung eingesetzt und angesehen werden koennen. Ferner werden die passive Solarenergienutzungen angesprochen und Messergebnisse eines Testzellengebaeudes vorgestellt. (BWI)

  11. Direct spectroscopic evidence for competition between thermal molecular agitation and magnetic field in a tetrameric protein in aqueous solution

    Science.gov (United States)

    Calabrò, Emanuele; Magazù, Salvatore

    2018-05-01

    Samples of a typical tetrameric protein, the hemoglobin, at the concentration of 150 mg/ml in bidistilled water solution, were exposed to a uniform magnetic field at 200 mT at different temperatures of 15∘C, 40∘C and 65∘C. Fourier Transform Infrared Spectroscopy was used to analyze the response of the secondary structure of the protein to both stress agents, heating and static magnetic field. The most relevant result which was observed was the significant increasing in intensity of the Amide I band after exposure to the uniform magnetic field at the room temperature of 15∘C. This result can be explained assuming that protein's α-helices aligned along the direction of the applied magnetic field due to their large dipole moment, inducing the alignment of the entire protein. Increasing of temperature up to 40∘C and 65∘C induced a significant reduction of the increasing in intensity of the Amide I band. This effect may be easily explained assuming that Brownian motion of the protein in water solution caused by thermal molecular agitation increased with increasing of temperature, contrasting the effect of the torque of the magnetic field applied to the protein in water solution.

  12. Controlling the diameters and field emission properties of vertically aligned carbon nanotubes synthesized by thermal chemical vapor deposition

    International Nuclear Information System (INIS)

    Choi, Sung Yool; Kang, Young Il; Cho, Kyoung Ik; Choi, Kyu Seok; Kim, Do Jin

    2001-01-01

    We report here the synthesis of vertically well-aligned carbon nanotubes and the effect of catalytic metal layer on the diameter of grown carbon nanotubes and the field emission characteristics of them, The carbon nanotubes were grown by thermal chemical vapor deposition at temperatures below 900 .deg. C on Fe metal catalytic layer, deposited by sputtering process on a Si substrate and pretreated by heat and NH 3 gas. We found that the thickness of metal layers could be an important parameter in controlling the diameters of carbon nanotubes. With varying the thickness of the metal layers the grain sizes of them also vary so that the diameters of the nanotubes could be controlled. Field emission measurement has been made on the carbon nanotube field emitters at room temperature in a vacuum chamber below 10 -6 Torr. Our vertically aligned carbon nanotube field emitter of the smallest diameter emits a current density about 10 mA/cm 2 at 7.2 V/μm. The field emission property of the carbon nanotubes shows strong dependence on the nanotube diameters as expected

  13. Seawater Circulation and Thermal Sink at OCEAN Ridges - FIELD Evidence in Oman Ophiolite

    Science.gov (United States)

    Nicolas, A. A.; Boudier, F. I.; Cathles, L. M.; Buck, W. R.; Celerier, B. P.

    2014-12-01

    Exceptionally, the lowermost gabbros in the Oman ophiolite are black and totally fresh, except for minute traces of impregnation by seawater fluids at very high temperature (~1000°C). These black gabbros sharply contrast with normal, whitish gabbros altered down to Low-T~500-350°C. These hydrous alterations are ascribed to an unconventional model of seawater circulation and cooling of the permanent magma chambers of fast spreading ocean ridges. In this model, gabbros issued from the magma chamber cross a ~100 m thick thermal boundary layer (TBL) before reaching a narrow, Low-T high permeability channel where the heated return seawater is flowing towards black smokers and the local gabbros are altered. Uprising mantle diapirs in Oman diverge at ~5 km on each side of the palaeo-ridge axis and feed an overlying magma chamber that closes at this distance from axis. Preservation of black gabbros along the Moho implies that the loop of seawater alteration locally does not reach Moho beyond this ~5km distance (otherwise black gabbros would be altered in whitish gabbros). This defines an internal "thermal sink" within ~5 km to the ridge axis. There, the sink is efficiently cooled by the active hydrothermal convection that is ridge transverse. This has been documented near the Galapagos ridge by marine geophysical data, within the same distance. Beyond this critical distance, the cooling system becomes dominantly conductive and ridge-parallel. The TBL and attached return flow channels must be rising into the overcooled, accreted crust. Beyond the thermal sink, the 500°C isotherm rebounds into the crust. It is only after ~ 1My of crustal drift that this isotherm penetrates into the uppermost mantle in a sustained fashion, developing serpentinites at the expense of peridotites.

  14. Thermal properties of milk fat, xanthine oxidase, caseins and whey proteins in pulsed electric field-treated bovine whole milk.

    Science.gov (United States)

    Sharma, Pankaj; Oey, Indrawati; Everett, David W

    2016-09-15

    Thermodynamics of milk components (milk fat, xanthine oxidase, caseins and whey proteins) in pulsed electric field (PEF)-treated milk were compared with thermally treated milk (63 °C for 30 min and 73 °C for 15s). PEF treatments were applied at 20 or 26 kV cm(-1) for 34 μs with or without pre-heating of milk (55 °C for 24s), using bipolar square wave pulses in a continuous mode of operation. PEF treatments did not affect the final temperatures of fat melting (Tmelting) or xanthine oxidase denaturation (Tdenaturation), whereas thermal treatments increased both the Tmelting of milk fat and the Tdenaturation for xanthine oxidase by 2-3 °C. Xanthine oxidase denaturation was ∼13% less after PEF treatments compared with the thermal treatments. The enthalpy change (ΔH of denaturation) of whey proteins decreased in the treated-milk, and denaturation increased with the treatment intensity. New endothermic peaks in the calorimetric thermograms of treated milk revealed the formation of complexes due to interactions between MFGM (milk fat globule membrane) proteins and skim milk proteins. Evidence for the adsorption of complexes onto the MFGM surface was obtained from the increase in surface hydrophobicity of proteins, revealing the presence of unfolded hydrophobic regions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Importance of initial buoyancy field on evolution of mantle thermal structure: Implications of surface boundary conditions

    Directory of Open Access Journals (Sweden)

    Petar Glišović

    2015-01-01

    Full Text Available Although there has been significant progress in the seismic imaging of mantle heterogeneity, the outstanding issue that remains to be resolved is the unknown distribution of mantle temperature anomalies in the distant geological past that give rise to the present-day anomalies inferred by global tomography models. To address this question, we present 3-D convection models in compressible and self-gravitating mantle initialised by different hypothetical temperature patterns. A notable feature of our forward convection modelling is the use of self-consistent coupling of the motion of surface tectonic plates to the underlying mantle flow, without imposing prescribed surface velocities (i.e., plate-like boundary condition. As an approximation for the surface mechanical conditions before plate tectonics began to operate we employ the no-slip (rigid boundary condition. A rigid boundary condition demonstrates that the initial thermally-dominated structure is preserved, and its geographical location is fixed during the evolution of mantle flow. Considering the impact of different assumed surface boundary conditions (rigid and plate-like on the evolution of thermal heterogeneity in the mantle we suggest that the intrinsic buoyancy of seven superplumes is most-likely resolved in the tomographic images of present-day mantle thermal structure. Our convection simulations with a plate-like boundary condition reveal that the evolution of an initial cold anomaly beneath the Java-Indonesian trench system yields a long-term, stable pattern of thermal heterogeneity in the lowermost mantle that resembles the present-day Large Low Shear Velocity Provinces (LLSVPs, especially below the Pacific. The evolution of subduction zones may be, however, influenced by the mantle-wide flow driven by deeply-rooted and long-lived superplumes since Archean times. These convection models also detect the intrinsic buoyancy of the Perm Anomaly that has been identified as a unique

  16. Miniature neutron sources: Thermal neutron sources and their users in the academic field

    International Nuclear Information System (INIS)

    Egelstaff, P.A.

    1992-01-01

    The three levels of thermal neutron sources are introduced - University laboratory sources infrastructure sources and world-class sources - and the needs for each kind and their inter-dependence will be emphasized. A description of the possibilities for University sources based on α-Be reactions or spontaneous fission emission is given, and current experience with them is described. A new generation of infrastructure sources is needed to continue the regional programs based on small reactors. Some possibilities for accelerator sources that could meet this need are considered

  17. High-power actively Q-switched single-mode 1342 nm Nd:YVO4 ring laser, injection-locked by a cw single-frequency microchip laser.

    Science.gov (United States)

    Koch, Peter; Bartschke, Juergen; L'huillier, Johannes A

    2015-11-30

    In this paper we report on the realization of a single-mode Q-switched Nd:YVO4 ring laser at 1342 nm. Unidirectional and single-mode operation of the ring laser is achieved by injection-locking with a continuous wave Nd:YVO4 microchip laser, emitting a single-frequency power of up to 40 mW. The ring laser provides a single-mode power of 13.9 W at 10 kHz pulse repetition frequency with a pulse duration of 18.2 ns and an excellent beam quality (M2 laser, a power of 8.7 W at 671 nm with a pulse duration of 14.8 ns and a beam propagation factor of M2 < 1.1 is obtained. The 671 nm radiation features a long-term spectral width of 75 MHz.

  18. Comparison of thermal and hemodynamic responses in skin and muscles to heating with electric and magnetic field

    Directory of Open Access Journals (Sweden)

    Karmen Glažar

    2015-06-01

    Full Text Available 12.00 Introduction: It has been shown that sufficient amount of energy provided by electromagnetic diathermy induces the increase of skin temperature and underlying tissues. However, scarce information is available on the differences in responses initiated by various techniques of diathermy. The goal of the present study was to compare thermal and hemodynamic responses of the skin and underlying muscles of the forearm to diathermy applied with electric (EF or magnetic field (MF. Methods: Eleven healthy volunteers participated in the study. On two separate occasions, they randomly received 20-minut diathermy with EF or with MF. Skin and tympanic temperature, and heart rate were measured. Further, kinetics of muscle oxyhemoglobin and deoxyhemoglobin kinetics were obtained. Thermal perception and thermal comfort were noted through the application of EF and MF. Results: The skin temperature increased similarly during the administration of EF and MF, by ~ 8.0 ± 1.3°C on both occasions. The thermal perception was more intense during the application of EF. Accordingly, the thermal comfort during the application of EF was perceived as less comfortable as compared with MF. During MF the increase in minute muscle blood flow and oxygen consumption was for ~ 42 % higher compared to the heating with EF. Conclusion: Although the increase in skin temperature was similar between EF and MF, the application of diathermy with MF was perceived more comfortable by the participants. Furthermore, the increase in minute muscle blood flow and oxygen consumption was higher in MF compared with EF. Thus, when muscle is the target tissue for physical therapy, a diathermy with magnetic field is the technique of choice. Normal 0 21 false false false SL X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Navadna tabela"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso

  19. INCREASING HEAVY OIL RESERVES IN THE WILMINGTON OIL FIELD THROUGH ADVANCED RESERVOIR CHARACTERIZATION AND THERMAL PRODUCTION TECHNOLOGIES

    Energy Technology Data Exchange (ETDEWEB)

    Unknown

    2001-08-08

    The objective of this project is to increase the recoverable heavy oil reserves within sections of the Wilmington Oil Field, near Long Beach, California, through the testing and application of advanced reservoir characterization and thermal production technologies. The hope is that successful application of these technologies will result in their implementation throughout the Wilmington Field and, through technology transfer, will be extended to increase the recoverable oil reserves in other slope and basin clastic (SBC) reservoirs. The existing steamflood in the Tar zone of Fault Block II-A (Tar II-A) has been relatively inefficient because of several producibility problems which are common in SBC reservoirs: inadequate characterization of the heterogeneous turbidite sands, high permeability thief zones, low gravity oil and non-uniform distribution of the remaining oil. This has resulted in poor sweep efficiency, high steam-oil ratios, and early steam breakthrough. Operational problems related to steam breakthrough, high reservoir pressure, and unconsolidated sands have caused premature well and downhole equipment failures. In aggregate, these reservoir and operational constraints have resulted in increased operating costs and decreased recoverable reserves. A suite of advanced reservoir characterization and thermal production technologies are being applied during the project to improve oil recovery and reduce operating costs, including: (1) Development of three-dimensional (3-D) deterministic and stochastic reservoir simulation models--thermal or otherwise--to aid in reservoir management of the steamflood and post-steamflood phases and subsequent development work. (2) Development of computerized 3-D visualizations of the geologic and reservoir simulation models to aid reservoir surveillance and operations. (3) Perform detailed studies of the geochemical interactions between the steam and the formation rock and fluids. (4) Testing and proposed application of a

  20. Impact of momentum anisotropy and turbulent chromo-fields on thermal particle production in quark-gluon-plasma medium

    Energy Technology Data Exchange (ETDEWEB)

    Chandra, Vinod [Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat (India); Sreekanth, V. [Indian Institute of Science, Centre for High Energy Physics, Bangalore (India)

    2017-06-15

    Momentum anisotropy present during the hydrodynamic evolution of the Quark-Gluon Plasma (QGP) in RHIC may lead to the chromo-Weibel instability and turbulent chromo-fields.The dynamics of the quark and gluon momentum distributions in this case is governed by an effective diffusive Vlasov equation (linearized). The solution of this linearized transport equation for the modified momentum distribution functions lead to the mathematical form of non-equilibrium momentum distribution functions of quarks/antiquarks and gluons. The modifications to these distributions encode the physics of turbulent color fields and momentum anisotropy. In the present manuscript, we employ these distribution functions to estimate the thermal dilepton production rate in the QGP medium. The production rate is seen to have appreciable sensitivity to the strength of the anisotropy. (orig.)