Meisner, Aaron M.; Finkbeiner, Douglas P.
2015-01-01
We apply the Finkbeiner et al. two-component thermal dust emission model to the Planck High Frequency Instrument maps. This parameterization of the far-infrared dust spectrum as the sum of two modified blackbodies (MBBs) serves as an important alternative to the commonly adopted single-MBB dust emission model. Analyzing the joint Planck/DIRBE dust spectrum, we show that two-component models provide a better fit to the 100-3000 GHz emission than do single-MBB models, though by a lesser margin than found by Finkbeiner et al. based on FIRAS and DIRBE. We also derive full-sky 6.'1 resolution maps of dust optical depth and temperature by fitting the two-component model to Planck 217-857 GHz along with DIRBE/IRAS 100 μm data. Because our two-component model matches the dust spectrum near its peak, accounts for the spectrum's flattening at millimeter wavelengths, and specifies dust temperature at 6.'1 FWHM, our model provides reliable, high-resolution thermal dust emission foreground predictions from 100 to 3000 GHz. We find that, in diffuse sky regions, our two-component 100-217 GHz predictions are on average accurate to within 2.2%, while extrapolating the Planck Collaboration et al. single-MBB model systematically underpredicts emission by 18.8% at 100 GHz, 12.6% at 143 GHz, and 7.9% at 217 GHz. We calibrate our two-component optical depth to reddening, and compare with reddening estimates based on stellar spectra. We find the dominant systematic problems in our temperature/reddening maps to be zodiacal light on large angular scales and the cosmic infrared background anisotropy on small angular scales.
Modeling Thermal Dust Emission with Two Components: Application to the Planck HFI Maps
Meisner, Aaron
2014-01-01
We apply the Finkbeiner et al. (1999) two-component thermal dust emission model to the Planck HFI maps. This parametrization of the far-infrared dust spectrum as the sum of two modified blackbodies serves as an important alternative to the commonly adopted single modified blackbody (MBB) dust emission model. Analyzing the joint Planck/DIRBE dust spectrum, we show that two-component models provide a better fit to the 100-3000 GHz emission than do single-MBB models, though by a lesser margin than found by Finkbeiner et al. (1999) based on FIRAS and DIRBE. We also derive full-sky 6.1' resolution maps of dust optical depth and temperature by fitting the two-component model to Planck 217-857 GHz along with DIRBE/IRAS 100 micron data. Because our two-component model matches the dust spectrum near its peak, accounts for the spectrum's flattening at millimeter wavelengths, and specifies dust temperature at 6.1' FWHM, our model provides reliable, high-resolution thermal dust emission foreground predictions from 100 to...
A two component model for thermal emission from organic grains in Comet Halley
Chyba, Christopher; Sagan, Carl
1988-01-01
Observations of Comet Halley in the near infrared reveal a triple-peaked emission feature near 3.4 micrometer, characteristic of C-H stretching in hydrocarbons. A variety of plausible cometary materials exhibit these features, including the organic residue of irradiated candidate cometary ices (such as the residue of irradiated methane ice clathrate, and polycyclic aromatic hydrocarbons. Indeed, any molecule containing -CH3 and -CH2 alkanes will emit at 3.4 micrometer under suitable conditions. Therefore tentative identifications must rest on additional evidence, including a plausible account of the origins of the organic material, a plausible model for the infrared emission of this material, and a demonstration that this conjunction of material and model not only matches the 3 to 4 micrometer spectrum, but also does not yield additional emission features where none is observed. In the case of the residue of irradiated low occupancy methane ice clathrate, it is argued that the lab synthesis of the organic residue well simulates the radiation processing experienced by Comet Halley.
Two-component Abelian sandpile models.
Alcaraz, F C; Pyatov, P; Rittenberg, V
2009-04-01
In one-component Abelian sandpile models, the toppling probabilities are independent quantities. This is not the case in multicomponent models. The condition of associativity of the underlying Abelian algebras imposes nonlinear relations among the toppling probabilities. These relations are derived for the case of two-component quadratic Abelian algebras. We show that Abelian sandpile models with two conservation laws have only trivial avalanches.
Two-component model of solar plages
Institute of Scientific and Technical Information of China (English)
LI; Jianping(李建平); DING; Mingde(丁明德); FANG; Cheng(方成)
2002-01-01
By use of the 2-m Mcmath-Pierce telescope at Kitt Peak, the high-quality spectra of a plage with moderate brightness near the center of solar disk were obtained. The data include seven spectral lines, which are Hα, Hβ, CaII H and K lines and the infrared triplet. With the consideration of fine structures of solar plages, a two-component atmospheric model is constructed by keeping the cool component to be the quiet atmosphere. Three cases of the hot component are given for different filling factors where the temperature and density distribution are adjusted in order to reproduce the seven observed spectral profiles. We also briefly discuss the influence of the column density at the base of the corona, m0, and the macro-turbulent velocity on the required filling factor and computed profiles. The two-component model is compared with precious one-component semi-empirical models. The limitation of the model is pointed out and further improvement is indicated.
A polaritonic two-component Bose-Hubbard model
Energy Technology Data Exchange (ETDEWEB)
Hartmann, M J; Brandao, F G S L; Plenio, M B [Institute for Mathematical Sciences, Imperial College London, 53 Exhibition Road, SW7 2PE (United Kingdom)], E-mail: m.hartmann@imperial.ac.uk
2008-03-15
We demonstrate that polaritons in an array of interacting micro-cavities with strong atom-photon coupling can form a two-component Bose-Hubbard model in which both polariton species are protected against spontaneous emission as their atomic part is stored in two ground states of the atoms. The parameters of the effective model can be tuned via the driving strength of external lasers and include attractive and repulsive polariton interactions. We also describe a method to measure the number statistics in one cavity for each polariton species independently.
A minimal model for two-component dark matter
Energy Technology Data Exchange (ETDEWEB)
Esch, Sonja; Klasen, Michael; Yaguna, Carlos E. [Institut fuer theoretische Physik, Universitaet Muenster, Wilhelm-Klemm-Strasse 9,D-48149 Muenster (Germany)
2015-07-01
We propose and study a new minimal model for two-component dark matter. The model contains only three additional fields, one fermion and two scalars, all singlets under the Standard Model gauge group. Two of these fields, one fermion and one scalar, are odd under a Z{sub 2} symmetry that renders them simultaneously stable. Thus, both particles contribute to the observed dark matter density. This model resembles the union of the singlet scalar and the singlet fermionic models but it contains some new features of its own. We analyze in some detail its dark matter phenomenology. Regarding the relic density, the main novelty is the possible annihilation of one dark matter particle into the other, which can affect the predicted relic density in a significant way. Regarding dark matter detection, we identify a new contribution that can lead either to an enhancement or to a suppression of the spin-independent cross section for the scalar dark matter particle. Finally, we define a set of five benchmarks models compatible with all present bounds and examine their direct detection prospects at planned experiments. A generic feature of this model is that both particles give rise to observable signals in 1-ton direct detection experiments. In fact, such experiments will be able to probe even a subdominant dark matter component at the percent level.
A minimal model for two-component dark matter
Esch, Sonja; Klasen, Michael; Yaguna, Carlos E.
2014-09-01
We propose and study a new minimal model for two-component dark matter. The model contains only three additional fields, one fermion and two scalars, all singlets under the Standard Model gauge group. Two of these fields, one fermion and one scalar, are odd under a Z 2 symmetry that renders them simultaneously stable. Thus, both particles contribute to the observed dark matter density. This model resembles the union of the singlet scalar and the singlet fermionic models but it contains some new features of its own. We analyze in some detail its dark matter phenomenology. Regarding the relic density, the main novelty is the possible annihilation of one dark matter particle into the other, which can affect the predicted relic density in a significant way. Regarding dark matter detection, we identify a new contribution that can lead either to an enhancement or to a suppression of the spin-independent cross section for the scalar dark matter particle. Finally, we define a set of five benchmarks models compatible with all present bounds and examine their direct detection prospects at planned experiments. A generic feature of this model is that both particles give rise to observable signals in 1-ton direct detection experiments. In fact, such experiments will be able to probe even a subdominant dark matter component at the percent level.
A minimal model for two-component dark matter
Esch, Sonja; Yaguna, Carlos E
2014-01-01
We propose and study a new minimal model for two-component dark matter. The model contains only three additional fields, one fermion and two scalars, all singlets under the Standard Model gauge group. Two of these fields, one fermion and one scalar, are odd under a $Z_2$ symmetry that renders them simultaneously stable. Thus, both particles contribute to the observed dark matter density. This model resembles the union of the singlet scalar and the singlet fermionic models but it contains some new features of its own. We analyze in some detail its dark matter phenomenology. Regarding the relic density, the main novelty is the possible annihilation of one dark matter particle into the other, which can affect the predicted relic density in a significant way. Regarding dark matter detection, we identify a new contribution that can lead either to an enhancement or to a suppression of the spin-independent cross section for the scalar dark matter particle. Finally, we define a set of five benchmarks models compatibl...
Implications of Two-component Dark Matter Induced by Forbidden Channels and Thermal Freeze-out
Aoki, Mayumi
2016-01-01
We consider a model of two-component dark matter based on a hidden $U(1)_D$ symmetry, in which relic densities of the dark matter are determined by forbidden channels and thermal freeze-out. The hidden $U(1)_D$ symmetry is spontaneously broken to a residual $\\mathbb{Z}_4$ symmetry, and the lightest $\\mathbb{Z}_4$ charged particle can be a dark matter candidate. Moreover, depending on the mass hierarchy in the dark sector, we have two-component dark matter. We show that the relic density of the lighter dark matter component can be determined by forbidden annihilation channels which require larger couplings compared to the normal freeze-out mechanism. As a result, a large self-interaction of the lighter dark matter component can be induced, which may solve small scale problems of $\\Lambda$CDM model. On the other hand, the heavier dark matter component is produced by normal freeze-out mechanism. We find that interesting implications emerge between the two dark matter components in this framework. We explore dete...
Transport of Solar Wind Fluctuations: A Two-Component Model
Oughton, S.; Matthaeus, W. H.; Smith, C. W.; Breech, B.; Isenberg, P. A.
2011-01-01
We present a new model for the transport of solar wind fluctuations which treats them as two interacting incompressible components: quasi-two-dimensional turbulence and a wave-like piece. Quantities solved for include the energy, cross helicity, and characteristic transverse length scale of each component, plus the proton temperature. The development of the model is outlined and numerical solutions are compared with spacecraft observations. Compared to previous single-component models, this new model incorporates a more physically realistic treatment of fluctuations induced by pickup ions and yields improved agreement with observed values of the correlation length, while maintaining good observational accord with the energy, cross helicity, and temperature.
Travelling wave solutions for some two-component shallow water models
Dutykh, Denys; Ionescu-Kruse, Delia
2016-07-01
In the present study we perform a unified analysis of travelling wave solutions to three different two-component systems which appear in shallow water theory. Namely, we analyze the celebrated Green-Naghdi equations, the integrable two-component Camassa-Holm equations and a new two-component system of Green-Naghdi type. In particular, we are interested in solitary and cnoidal-type solutions, as two most important classes of travelling waves that we encounter in applications. We provide a complete phase-plane analysis of all possible travelling wave solutions which may arise in these models. In particular, we show the existence of new type of solutions.
Instabilities on crystal surfaces: The two-component body-centered solid-on-solid model
Carlon, E.; van Beijeren, H.; Mazzeo, G.
1996-01-01
The free energy of crystal surfaces that can be described by the two-component body-centered solid-on-solid model has been calculated in a mean-field approximation. The system may model ionic crystals with a bcc lattice structure (for instance CsCl). Crossings between steps are energetically favored
Domain Walls and Textured Vortices in a Two-Component Ginzburg-Landau Model
DEFF Research Database (Denmark)
Madsen, Søren Peder; Gaididei, Yu. B.; Christiansen, Peter Leth
2005-01-01
We look for domain wall and textured vortex solutions in a two-component Ginzburg-Landau model inspired by two-band superconductivity. The two-dimensional two-component model, with equal coherence lengths and no magnetic field, shows some interesting properties. In the absence of a Josephson type...... coupling between the two order parameters a ''textured vortex'' is found by analytical and numerical solution of the Ginzburg-Landau equations. With a Josephson type coupling between the two order parameters we find the system to split up in two domains separated by a domain wall, where the order parameter...
Domain Walls and Textured Vortices in a Two-Component Ginzburg-Landau Model
DEFF Research Database (Denmark)
Madsen, Søren Peder; Gaididei, Yu. B.; Christiansen, Peter Leth
2005-01-01
We look for domain wall and textured vortex solutions in a two-component Ginzburg-Landau model inspired by two-band superconductivity. The two-dimensional two-component model, with equal coherence lengths and no magnetic field, shows some interesting properties. In the absence of a Josephson type...... coupling between the two order parameters a ''textured vortex'' is found by analytical and numerical solution of the Ginzburg-Landau equations. With a Josephson type coupling between the two order parameters we find the system to split up in two domains separated by a domain wall, where the order parameter...
Two-component model of the interaction of an interstellar cloud with surrounding hot plasma
Provornikova, E. A.; Izmodenov, V. V.; Lallement, R.
2011-01-01
We present a two-component gasdynamic model of an interstellar cloud embedded in a hot plasma. It is assumed that the cloud consists of atomic hydrogen gas, interstellar plasma is quasineutral. Hydrogen atoms and plasma protons interact through a charge exchange process. Magnetic felds and radiative processes are ignored in the model. The influence of heat conduction within plasma on the interaction between a cloud and plasma is studied. We consider the extreme case and assume that hot plasma...
Modelling elliptical galaxies phase-space constraints on two-component (gamma1,gamma2) models
Ciotti, L
1999-01-01
In the context of the study of the properties of the mutual mass distribution of the bright and dark matter in elliptical galaxies, present a family of two-component, spherical, self-consistent galaxy models, where one density distribution follows a gamma_1 profile, and the other a gamma_2 profile [(gamma_1,gamma_2) models], with different total masses and ``core'' radii. A variable amount of Osipkov-Merritt (radial) orbital anisotropy is allowed in both components. For these models, I derive analytically the necessary and sufficient conditions that the model parameters must satisfy in order to correspond to a physical system. Moreover, the possibility of adding a black hole at the center of radially anisotropic gamma models is discussed, determining analytically a lower limit of the anisotropy radius as a function of gamma. The analytical phase-space distribution function for (1,0) models is presented, together with the solution of the Jeans equations and the quantities entering the scalar virial theorem. It...
Indian Academy of Sciences (India)
Surendra P Verma
2000-03-01
This paper presents error propagation equations for modeling of radiogenic isotopes during mixing of two components or end-members. These equations can be used to estimate errors on an isotopic ratio in the mixture of two components, as a function of the analytical errors or the total errors of geological field sampling and analytical errors. Two typical cases (``Small errors'' and ``Large errors'') are illustrated for mixing of Sr isotopes. Similar examples can be formulated for the other radiogenic isotopic ratios. Actual isotopic data for sediment and basalt samples from the Cocos plate are also included to further illustrate the use of these equations. The isotopic compositions of the predicted mixtures can be used to constrain the origin of magmas in the central part of the Mexican Volcanic Belt. These examples show the need of high quality experimental data for them to be useful in geochemical modeling of magmatic processes.
A two-component Frenkel-Kontorowa model for surface alloy formation
Daruka, I
2003-01-01
It has been shown by recent experiments that bulk immiscible metals (e.g. Ag/Cu, Ag/Co and Au/Ni) can form binary alloys on certain surfaces where the substrate mediates the elastic misfits between the two components, thus relieving the elastic strain in the overlayer. These novel surface alloys exhibit a rich phase structure. We formulate a two-component Frenkel-Kontorova model in one dimension to study surface alloy formation. This model can naturally incorporate dislocation formation that plays a crucial role in determining the actual structure of the system. Using energy minimization calculations we provide a phase diagram in terms of average alloy composition and the energy of mixing. Monte Carlo simulations were also performed to study the structure and interaction of the emerging dislocations.
Qu, Jingyuan; Kadic, Muamer; Naber, Andreas; Wegener, Martin
2017-01-01
Controlling the thermal expansion of materials is of great technological importance. Uncontrolled thermal expansion can lead to failure or irreversible destruction of structures and devices. In ordinary crystals, thermal expansion is governed by the asymmetry of the microscopic binding potential, which cannot be adjusted easily. In artificial crystals called metamaterials, thermal expansion can be controlled by structure. Here, following previous theoretical work, we fabricate three-dimensional (3D) two-component polymer micro-lattices by using gray-tone laser lithography. We perform cross-correlation analysis of optical microscopy images taken at different sample temperatures. The derived displacement-vector field reveals that the thermal expansion and resulting bending of the bi-material beams leads to a rotation of the 3D chiral crosses arranged onto a 3D checkerboard pattern within one metamaterial unit cell. These rotations can compensate the expansion of the all positive constituents, leading to an effectively near-zero thermal length-expansion coefficient, or over-compensate the expansion, leading to an effectively negative thermal length-expansion coefficient. This evidences a striking level of thermal-expansion control.
Mapping the Two-Component Atomic Fermi Gas to the Nuclear Shell-Model
DEFF Research Database (Denmark)
Özen, C.; Zinner, Nikolaj Thomas
2014-01-01
of the external potential becomes important. A system of two-species fermionic cold atoms with an attractive zero-range interaction is analogous to a simple model of nucleus in which neutrons and protons interact only through a residual pairing interaction. In this article, we discuss how the problem of a two......-component atomic fermi gas in a tight external trap can be mapped to the nuclear shell model so that readily available many-body techniques in nuclear physics, such as the Shell Model Monte Carlo (SMMC) method, can be directly applied to the study of these systems. We demonstrate an application of the SMMC method...
Robinson, P. A.; Newman, D. L.
1990-01-01
A simple two-component model of strong turbulence that makes clear predictions for the scalings, spectra, and statistics of Langmuir waves is developed. Scalings of quantities such as energy density, power input, dissipation power wave collapse, and number density of collapsing objects are investigated in detail and found to agree well with model predictions. The nucleation model of wave-packet formation is strongly supported by the results. Nucleation proceeds with energy flowing from background to localized states even in the absence of a driver. Modulational instabilities play little or no role in maintaining the turbulent state when significant density nonuniformities are present.
Mapping the Two-Component Atomic Fermi Gas to the Nuclear Shell-Model
DEFF Research Database (Denmark)
Özen, C.; Zinner, Nikolaj Thomas
2014-01-01
The physics of a two-component cold fermi gas is now frequently addressed in laboratories. Usually this is done for large samples of tens to hundreds of thousands of particles. However, it is now possible to produce few-body systems (1-100 particles) in very tight traps where the shell structure...... of the external potential becomes important. A system of two-species fermionic cold atoms with an attractive zero-range interaction is analogous to a simple model of nucleus in which neutrons and protons interact only through a residual pairing interaction. In this article, we discuss how the problem of a two...
Two-component model of the interaction of an interstellar cloud with surrounding hot plasma
Provornikova, E A; Lallement, R
2011-01-01
We present a two-component gasdynamic model of an interstellar cloud embedded in a hot plasma. It is assumed that the cloud consists of atomic hydrogen gas, interstellar plasma is quasineutral. Hydrogen atoms and plasma protons interact through a charge exchange process. Magnetic felds and radiative processes are ignored in the model. The influence of heat conduction within plasma on the interaction between a cloud and plasma is studied. We consider the extreme case and assume that hot plasma electrons instantly heat the plasma in the interaction region and that plasma flow can be described as isothermal. Using the two-component model of the interaction of cold neutral cloud and hot plasma, we estimate the lifetime of interstellar clouds. We focus on the clouds typical for the cluster of local interstellar clouds embedded in the hot Local Bubble and give an estimate of the lifetime of the Local interstellar cloud where the Sun currently travels. The charge transfer between highly charged plasma ions and neutr...
Sin, Kuek Jia; Cheong, Chin Wen; Hooi, Tan Siow
2017-04-01
This study aims to investigate the crude oil volatility using a two components autoregressive conditional heteroscedasticity (ARCH) model with the inclusion of abrupt jump feature. The model is able to capture abrupt jumps, news impact, clustering volatility, long persistence volatility and heavy-tailed distributed error which are commonly observed in the crude oil time series. For the empirical study, we have selected the WTI crude oil index from year 2000 to 2016. The results found that by including the multiple-abrupt jumps in ARCH model, there are significant improvements of estimation evaluations as compared with the standard ARCH models. The outcomes of this study can provide useful information for risk management and portfolio analysis in the crude oil markets.
Modeling and Simulation of Two-Phase Two-Component Flow with Disappearing Nonwetting Phase
Neumann, Rebecca; Ippisch, Olaf
2012-01-01
Carbon Capture and Storage (CCS) is a recently discussed new technology, aimed at allowing an ongoing use of fossil fuels while preventing the produced CO2 to be released to the atmosphere. CSS can be modeled with two components (water and CO2) in two phases (liquid and CO2). To simulate the process, a multiphase flow equation with equilibrium phase exchange is used. One of the big problems arising in two-phase two-component flow simulations is the disappearance of the nonwetting phase, which leads to a degeneration of the equations satisfied by the saturation. A standard choice of primary variables, which is the pressure of one phase and the saturation of the other phase, cannot be applied here. We developed a new approach using the pressure of the nonwetting phase and the capillary pressure as primary variables. One important advantage of this approach is the fact that we have only one set of primary variables that can be used for the biphasic as well as the monophasic case. We implemented this new choice o...
Two-component mixture model: Application to palm oil and exchange rate
Phoong, Seuk-Yen; Ismail, Mohd Tahir; Hamzah, Firdaus Mohamad
2014-12-01
Palm oil is a seed crop which is widely adopt for food and non-food products such as cookie, vegetable oil, cosmetics, household products and others. Palm oil is majority growth in Malaysia and Indonesia. However, the demand for palm oil is getting growth and rapidly running out over the years. This phenomenal cause illegal logging of trees and destroy the natural habitat. Hence, the present paper investigates the relationship between exchange rate and palm oil price in Malaysia by using Maximum Likelihood Estimation via Newton-Raphson algorithm to fit a two components mixture model. Besides, this paper proposes a mixture of normal distribution to accommodate with asymmetry characteristics and platykurtic time series data.
Freshwater DOM quantity and quality from a two-component model of UV absorbance
Carter, Heather T.; Tipping, Edward; Koprivnjak, Jean-Francois; Miller, Matthew P.; Cookson, Brenda; Hamilton-Taylor, John
2012-01-01
We present a model that considers UV-absorbing dissolved organic matter (DOM) to consist of two components (A and B), each with a distinct and constant spectrum. Component A absorbs UV light strongly, and is therefore presumed to possess aromatic chromophores and hydrophobic character, whereas B absorbs weakly and can be assumed hydrophilic. We parameterised the model with dissolved organic carbon concentrations [DOC] and corresponding UV spectra for c. 1700 filtered surface water samples from North America and the United Kingdom, by optimising extinction coefficients for A and B, together with a small constant concentration of non-absorbing DOM (0.80 mg DOC L-1). Good unbiased predictions of [DOC] from absorbance data at 270 and 350 nm were obtained (r2 = 0.98), the sum of squared residuals in [DOC] being reduced by 66% compared to a regression model fitted to absorbance at 270 nm alone. The parameterised model can use measured optical absorbance values at any pair of suitable wavelengths to calculate both [DOC] and the relative amounts of A and B in a water sample, i.e. measures of quantity and quality. Blind prediction of [DOC] was satisfactory for 9 of 11 independent data sets (181 of 213 individual samples).
Sander, Myriam C; Werkle-Bergner, Markus; Gerjets, Peter; Shing, Yee Lee; Lindenberger, Ulman
2012-02-15
We recently introduced a two-component model of the mechanisms underlying age differences in memory functioning across the lifespan. According to this model, memory performance is based on associative and strategic components. The associative component is relatively mature by middle childhood, whereas the strategic component shows a maturational lag and continues to develop until young adulthood. Focusing on work from our own lab, we review studies from the domains of episodic and working memory informed by this model, and discuss their potential implications for educational settings. The episodic memory studies uncover the latent potential of the associative component in childhood by documenting children's ability to greatly improve their memory performance following mnemonic instruction and training. The studies on working memory also point to an immature strategic component in children whose operation is enhanced under supportive conditions. Educational settings may aim at fostering the interplay between associative and strategic components. We explore possible routes towards this goal by linking our findings to recent trends in research on instructional design. Copyright © 2011 Elsevier Ltd. All rights reserved.
Bioorthogonal two-component drug delivery in HER2(+) breast cancer mouse models
Hapuarachchige, Sudath; Kato, Yoshinori; Artemov, Dmitri
2016-04-01
The HER2 receptor is overexpressed in approximately 20% of breast cancers and is associated with tumorigenesis, metastasis, and a poor prognosis. Trastuzumab is a first-line targeted drug used against HER2(+) breast cancers; however, at least 50% of HER2(+) tumors develop resistance to trastuzumab. To treat these patients, trastuzumab-based antibody-drug conjugates (ACDs) have been developed and are currently used in the clinic. Despite their high efficacy, the long circulation half-life and non-specific binding of cytotoxic ADCs can result in systemic toxicity. In addition, standard ADCs do not provide an image-guided mode of administration. Here, we have developed a two-component, two-step, pre-targeting drug delivery system integrated with image guidance to circumvent these issues. In this strategy, HER2 receptors are pre-labeled with a functionalized trastuzumab antibody followed by the delivery of drug-loaded nanocarriers. Both components are cross-linked by multiple bioorthogonal click reactions in situ on the surface of the target cell and internalized as nanoclusters. We have explored the efficacy of this delivery strategy in HER2(+) human breast cancer models. Our therapeutic study confirms the high therapeutic efficacy of the new delivery system, with no significant toxicity.
Large-scale Models Reveal the Two-component Mechanics of Striated Muscle
Directory of Open Access Journals (Sweden)
Robert Jarosch
2008-12-01
Full Text Available This paper provides a comprehensive explanation of striated muscle mechanics and contraction on the basis of filament rotations. Helical proteins, particularly the coiled-coils of tropomyosin, myosin and ÃŽÂ±-actinin, shorten their H-bonds cooperatively and produce torque and filament rotations when the Coulombic net-charge repulsion of their highly charged side-chains is diminished by interaction with ions. The classical Ã¢Â€Âœtwo-component modelÃ¢Â€Â of active muscle differentiated a Ã¢Â€Âœcontractile componentÃ¢Â€Â which stretches the Ã¢Â€Âœseries elastic componentÃ¢Â€Â during force production. The contractile components are the helically shaped thin filaments of muscle that shorten the sarcomeres by clockwise drilling into the myosin cross-bridges with torque decrease (= force-deficit. Muscle stretch means drawing out the thin filament helices off the cross-bridges under passive counterclockwise rotation with torque increase (= stretch activation. Since each thin filament is anchored by four elastic ÃŽÂ±-actinin Z-filaments (provided with forceregulating sites for Ca2+ binding, the thin filament rotations change the torsional twist of the four Z-filaments as the Ã¢Â€Âœseries elastic componentsÃ¢Â€Â. Large scale models simulate the changes of structure and force in the Z-band by the different Z-filament twisting stages A, B, C, D, E, F and G. Stage D corresponds to the isometric state. The basic phenomena of muscle physiology, i. e. latency relaxation, Fenn-effect, the force-velocity relation, the length-tension relation, unexplained energy, shortening heat, the Huxley-Simmons phases, etc. are explained and interpreted with the help of the model experiments.
Discrete kink dynamics in hydrogen-bonded chains: The two-component model
DEFF Research Database (Denmark)
Karpan, V.M.; Zolotaryuk, Yaroslav; Christiansen, Peter Leth
2004-01-01
We study discrete topological solitary waves (kinks and antikinks) in two nonlinear diatomic chain models that describe the collective dynamics of proton transfers in one-dimensional hydrogen-bonded networks. The essential ingredients of the models are (i) a realistic (anharmonic) ion-proton inte......We study discrete topological solitary waves (kinks and antikinks) in two nonlinear diatomic chain models that describe the collective dynamics of proton transfers in one-dimensional hydrogen-bonded networks. The essential ingredients of the models are (i) a realistic (anharmonic) ion...... principal differences, like a significant difference in the stability switchings behavior for the kinks and the antikinks. Water-filled carbon nanotubes are briefly discussed as possible realistic systems, where topological discrete (anti)kink states might exist....
Two Component Dark Matters in S_4 x Z_2 Flavor Symmetric Extra U(1) Model
Daikoku, Yasuhiro; Toma, Takashi
2011-01-01
We study cosmic-ray anomaly observed by PAMELA based on E_6 inspired extra U(1) model with S_4 x Z_2 flavor symmetry. In our model, the lightest flavon has very long lifetime of O(10^{18)) second which is longer than the age of the universe, but not long enough to explain the PAMELA result ~ O(10^{26}) sec. Such a situation could be avoidable by considering that the flavon is not the dominant component of dark matters and the dominant one is the lightest neutralino. With appropriate parameter set, density parameter of dark matter and over-abundance of positron flux in cosmic-ray are realized at the same time. There is interesting correlation between spectrum of positron flux and V_{MNS}. No excess of anti-proton in cosmic-ray suggests that sfermions are heavier than 4 TeV and the masses of the light Higgs bosons are degenerated.
Two-Component Jet Models of Gamma-Ray Burst Sources
Peng, F; Granot, J; Peng, Fang; Konigl, Arieh; Granot, Jonathan
2004-01-01
Recent observational and theoretical studies have raised the possibility that the collimated outflows in gamma-ray burst (GRB) sources have two distinct components: a narrow (opening half-angle $\\theta_{\\rm n}$), highly relativistic (initial Lorentz factor $\\eta_\\rmn \\gtrsim 10^2$) outflow, from which the $\\gamma$-ray emission originates, and a wider ($\\theta_{\\rm w} \\lesssim 3 \\theta_{\\rm n}$), moderately relativistic ($\\eta_{\\rm w}\\sim 10$) surrounding flow. Using a simple synchrotron emission model, we calculate the R-band afterglow lightcurves expected in this scenario and derive algebraic expressions for the flux ratios of the emission from the two jet components at the main transition times in the lightcurve. We apply this model to GRB sources, for explaining the structure of afterglows and source energetics, as well as to X-ray flash sources, which we interpret as GRB jets viewed at an angle $\\theta_{\\rm obs} > \\theta_{\\rm n}$. Finally, we argue that a neutron-rich hydromagnetic outflow may naturally g...
Three-body recombination of two-component cold atomic gases into deep dimers in an optical model
DEFF Research Database (Denmark)
Mikkelsen, Mathias; Jensen, A. S.; Fedorov, D. V.
2015-01-01
We consider three-body recombination into deep dimers in a mass-imbalanced two-component atomic gas. We use an optical model where a phenomenological imaginary potential is added to the lowest adiabatic hyper-spherical potential. The consequent imaginary part of the energy eigenvalue corresponds...... to the decay rate or recombination probability of the three-body system. The method is formulated in details and the relevant qualitative features are discussed as functions of scattering lengths and masses. We use zero-range model in analyses of recent recombination data. The dominating scattering length...
Numerical modeling of sintering of two-component metal powders with laser beams
Niziev, V. G.; Koldoba, A. V.; Mirzade, F. Kh.; Panchenko, V. Ya.; Poveschenko, Yu. A.; Popov, M. V.
2011-02-01
Direct laser sintering of a mixture of two metal powders with significantly different melting points is investigated by numerical simulation. The model is based on self-consistent non-linear continuity equations for volume fractions of components and on energy transfer equations for the powder mixture. It includes the movement of the solid particles due to shrinkage because of the density change of the powder mixture and the liquid flow driven by the capillary and gravity forces. The liquid flow is determined by Darcy's law. The effect of surface settlement of the powder is obtained. The width increasing rate of the melting zone depend both on the parameters of the laser radiation (on the power of the beam) and on the physical parameters of the particle's material, and it increases with the increasing of the penetrability or the increasing of the phase-transition heat. The increasing of the laser power under other factors being equal results in the acceleration of the melting front propagation.
Kierzek, Andrzej M; Zhou, Lu; Wanner, Barry L
2010-03-01
Two-component systems (TCSs) are prevalent signal transduction systems in bacteria that control innumerable adaptive responses to environmental cues and host-pathogen interactions. We constructed a detailed stochastic kinetic model of two component signalling based on published data. Our model has been validated with flow cytometry data and used to examine reporter gene expression in response to extracellular signal strength. The model shows that, depending on the actual kinetic parameters, TCSs exhibit all-or-none, graded or mixed mode responses. In accordance with other studies, positively autoregulated TCSs exhibit all-or-none responses. Unexpectedly, our model revealed that TCSs lacking a positive feedback loop exhibit not only graded but also mixed mode responses, in which variation of the signal strength alters the level of gene expression in induced cells while the regulated gene continues to be expressed at the basal level in a substantial fraction of cells. The graded response of the TCS changes to mixed mode response by an increase of the translation initiation rate of the histidine kinase. Thus, a TCS is an evolvable design pattern capable of implementing deterministic regulation and stochastic switches associated with both graded and threshold responses. This has implications for understanding the emergence of population diversity in pathogenic bacteria and the design of genetic circuits in synthetic biology applications. The model is available in systems biology markup language (SBML) and systems biology graphical notation (SBGN) formats and can be used as a component of large-scale biochemical reaction network models.
Energy Technology Data Exchange (ETDEWEB)
Butlitsky, M. A.; Zelener, B. V. [Joint Institute for High Temperature of Russian Academy of Science, 125412, Russia, Moscow, Izhorskaya str. 13/2 (Russian Federation); Zelener, B. B. [Joint Institute for High Temperature of Russian Academy of Science, 125412, Russia, Moscow, Izhorskaya str. 13/2 (Russian Federation); Moscow Engineering Physics Institute, 115409, Russia, Moscow, Kashirskoe sh. 31 (Russian Federation)
2014-07-14
A two-component plasma model, which we called a “shelf Coulomb” model has been developed in this work. A Monte Carlo study has been undertaken to calculate equations of state, pair distribution functions, internal energies, and other thermodynamics properties. A canonical NVT ensemble with periodic boundary conditions was used. The motivation behind the model is also discussed in this work. The “shelf Coulomb” model can be compared to classical two-component (electron-proton) model where charges with zero size interact via a classical Coulomb law. With important difference for interaction of opposite charges: electrons and protons interact via the Coulomb law for large distances between particles, while interaction potential is cut off on small distances. The cut off distance is defined by an arbitrary ε parameter, which depends on system temperature. All the thermodynamics properties of the model depend on dimensionless parameters ε and γ = βe{sup 2}n{sup 1/3} (where β = 1/k{sub B}T, n is the particle's density, k{sub B} is the Boltzmann constant, and T is the temperature) only. In addition, it has been shown that the virial theorem works in this model. All the calculations were carried over a wide range of dimensionless ε and γ parameters in order to find the phase transition region, critical point, spinodal, and binodal lines of a model system. The system is observed to undergo a first order gas-liquid type phase transition with the critical point being in the vicinity of ε{sub crit}≈13(T{sub crit}{sup *}≈0.076),γ{sub crit}≈1.8(v{sub crit}{sup *}≈0.17),P{sub crit}{sup *}≈0.39, where specific volume v* = 1/γ{sup 3} and reduced temperature T{sup *} = ε{sup −1}.
Butlitsky, M A; Zelener, B B; Zelener, B V
2014-07-14
A two-component plasma model, which we called a "shelf Coulomb" model has been developed in this work. A Monte Carlo study has been undertaken to calculate equations of state, pair distribution functions, internal energies, and other thermodynamics properties. A canonical NVT ensemble with periodic boundary conditions was used. The motivation behind the model is also discussed in this work. The "shelf Coulomb" model can be compared to classical two-component (electron-proton) model where charges with zero size interact via a classical Coulomb law. With important difference for interaction of opposite charges: electrons and protons interact via the Coulomb law for large distances between particles, while interaction potential is cut off on small distances. The cut off distance is defined by an arbitrary ɛ parameter, which depends on system temperature. All the thermodynamics properties of the model depend on dimensionless parameters ɛ and γ = βe(2)n(1/3) (where β = 1/kBT, n is the particle's density, kB is the Boltzmann constant, and T is the temperature) only. In addition, it has been shown that the virial theorem works in this model. All the calculations were carried over a wide range of dimensionless ɛ and γ parameters in order to find the phase transition region, critical point, spinodal, and binodal lines of a model system. The system is observed to undergo a first order gas-liquid type phase transition with the critical point being in the vicinity of ɛ(crit) ≈ 13(T(*)(crit) ≈ 0.076), γ(crit) ≈ 1.8(v(*)(crit) ≈ 0.17), P(*)(crit) ≈ 0.39, where specific volume v* = 1/γ(3) and reduced temperature T(*) = ɛ(-1).
Three-body recombination of two-component cold atomic gases into deep dimers in an optical model
DEFF Research Database (Denmark)
Mikkelsen, Mathias; Jensen, A. S.; Fedorov, D. V.
2015-01-01
. The Efimov scaling between recombination peaks is calculated and shown to depend on both scattering lengths. Recombination is predicted to be largest for heavy-heavy-light systems. Universal properties of the optical parameters are indicated. We compare to available experiments and find in general very......We consider three-body recombination into deep dimers in a mass-imbalanced two-component atomic gas. We use an optical model where a phenomenological imaginary potential is added to the lowest adiabatic hyper-spherical potential. The consequent imaginary part of the energy eigenvalue corresponds...... to the decay rate or recombination probability of the three-body system. The method is formulated in details and the relevant qualitative features are discussed as functions of scattering lengths and masses. We use zero-range model in analyses of recent recombination data. The dominating scattering length...
Ross, Scott R; Hertenstein, Matthew J; Wrobel, Thomas A
2007-04-01
In a sample composed of 162 young adults, we examined the generalizability of an orthogonal, 2-component model of forgiveness previously reported by Ross, Kendall, Matters, Rye, and Wrobel (2004). Furthermore, we examined the relationship of these two components with maladaptive personality characteristics as measured by the Schedule for Nonadaptive and Adaptive Personality (SNAP; Clark, 1993), with an emphasis on Five-factor model markers of personality. Using multiple measures of forgiveness, principal components analysis supported a 2-component model representing self-forgiveness and other forgiveness. Despite the independence of self-forgiveness and other forgiveness, zero order correlations with SNAP scales supported convergent more than discriminant validity. In contrast, hierarchical multiple regression analyses emphasized the discriminant validity of self-forgiveness and other forgiveness. Among indices of Neuroticism, Extraversion, and Agreeableness, Negative Temperament (+) was the sole predictor of self-forgiveness. In contrast, Positive Temperament (+), Aggression (-), and Histrionic PD (-) were most associated with other forgiveness. Overall, these findings support the validity of these factors and highlight the importance of self-forgiveness in clinical assessment.
A two-component jet model based on the Blandford-Znajek and Blandford-Payne processes
Xie, Wei; Zou, Yuan-Chuan; Wang, Ding-Xiong; Wu, Qingwen; Wang, Jiu-Zhou
2012-01-01
We propose a two-component jet model consistent with the observations of several gamma ray bursts (GRBs) and active galactic nuclei (AGNs). The jet consists of inner and outer components, and they are supposed to be driven by the Blandford-Znajek (BZ) and Blandford-Payne (BP) processes, respectively. The baryons in the BP jet is accelerated centrifugally via the magnetic field anchored in the accretion disk. The BZ jet is assumed to be entrained a fraction of accreting matter leaving the inner edge of the accretion disk, and the baryons are accelerated in the conversion from electromagnetic energy to the kinetic energy. By fitting the Lorentz factors of some GRBs (GRB 030329, GRB 051221A, GRB 080413B) and AGNs (Cen A, Mkn 501 and Mkn 421) with this model, we constrain the physical parameters related to the accretion and outflow of these two kind of objects. We conclude that the spine/sheath structure of the jet from these sources can be interpreted naturally by the BZ and BP processes.
A two-component jet model based on the Blandford-Znajek and Blandford-Payne processes
Xie, Wei; Lei, Wei-Hua; Zou, Yuan-Chuan; Wang, Ding-Xiong; Wu, Qingwen; Wang, Jiu-Zhou
2012-07-01
We propose a two-component jet model consistent with the observations of several gamma ray bursts (GRBs) and active galactic nuclei (AGNs). The jet consists of inner and outer components, which are supposed to be driven by the Blandford-Znajek (BZ) and Blandford-Payne (BP) processes, respectively. The baryons in the BP jet are accelerated centrifugally via the magnetic field anchored in the accretion disk. The BZ jet is assumed to be entrained in a fraction of accreting matter leaving the inner edge of the accretion disk, and the baryons are accelerated in the conversion from electromagnetic energy to kinetic energy. By fitting the Lorentz factors of some GRBs (GRB 030329, GRB 051221A and GRB 080413B) and AGNs (Cen A, Mkn 501 and Mkn 421) with this model, we constrain the physical parameters related to the accretion and outflow of these two kinds of objects. We conclude that the spine/sheath structure of the jet from these sources can be interpreted naturally by the BZ and BP processes.
A two-component jet model based on the Blandford-Znajek and Blandford-Payne processes
Institute of Scientific and Technical Information of China (English)
Wei Xie; Wei-Hua Lei; Yuan-Chuan Zou; Ding-Xiong Wang; Qingwen Wu; Jiu-Zhou Wang
2012-01-01
We propose a two-component jet model consistent with the observations of several gamma ray bursts(GRBs)and active galactic nuclei(AGNs).The jet consists of inner and outer components,which are supposed to be driven by the BlandfordZnajek(BZ)and Blandford-Payne(BP)processes,respectively.The baryons in the BP jet are accelerated centrifugally via the magnetic field anchored in the accretion disk.The BZ jet is assumed to be entrained in a fraction of accreting matter leaving the inner edge of the accretion disk,and the baryons are accelerated in the conversion from electromagnetic energy to kinetic energy.By fitting the Lorentz factors of some GRBs(GRB 030329,GRB 051221A and GRB 080413B)and AGNs(Cen A,Mkn 501 and Mkn 421)with this model,we constrain the physical parameters related to the accretion and outflow of these two kinds of objects.We conclude that the spine/sheath structure of the jet from these sources can be interpreted naturally by the BZ and BP processes.
Belotsky, K; Kouvaris, C; Laletin, M
2015-01-01
We study a two component dark matter candidate inspired by the Minimal Walking Technicolor model. Dark matter consists of a dominant SIMP-like dark atom component made of bound states between primordial helium nuclei and a doubly charged technilepton, and a small WIMP-like component made of another dark atom bound state between a doubly charged technibaryon and a technilepton. This scenario is consistent with direct search experimental findings because the dominant SIMP component interacts too strongly to reach the depths of current detectors with sufficient energy to recoil and the WIMP-like component is too small to cause significant amount of events. In this context a metastable technibaryon that decays to $e^+e^+$, $\\mu^+ \\mu^+$ and $\\tau^+ \\tau^+$ can in principle explain the observed positron excess by AMS-02 and PAMELA, while being consistent with the photon flux observed by FERMI/LAT. We scan the parameters of the model and we find the best possible fit to the latest experimental data. We find that th...
Rafal Podlaski; Francis Roesch
2014-01-01
In recent years finite-mixture models have been employed to approximate and model empirical diameter at breast height (DBH) distributions. We used two-component mixtures of either the Weibull distribution or the gamma distribution for describing the DBH distributions of mixed-species, two-cohort forest stands, to analyse the relationships between the DBH components,...
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
We re-examine the ten Reverberation Mapping(RM) sources with public data based on the two-component model of the Broad Line Region(BLR).In fitting their broad Hβ Mlines,six of them only need one Gaussian component,one of them has a double-peak profile,one has an irregular profile,and only two of them need two components,i.e.,a Very Broad Gaussian Component(VBGC) and an Inter-Mediate Gaussian Component(IMGC).The Gaussian components are assumed to come from two distinct regions in the two-component model;they are the Very Broad Line Region(VBLR) and the Inter-Mediate Line region(IMLR).The two sources with a two-component profile are Mrk 509 and NGC 4051.The time lags of the two components of both sources satisfy tIMLR/tVBLR=V 2VBLR/V 2IMLR,where tIMLR and tVBLR are the lags of the two components while VIMLR and VVBLR represent the mean gas velocities of the two regions,supporting the two-component model of the BLR of Active Galactic Nuclei(AGNs).The fact that most of these ten sources only have the VBGC confirms the assumption that RM mainly measures the radius of the VBLR;consequently,the radius obtained from the R-L relationship mainly represents the radius of VBLR.Moreover,NGC 4051,with a lag of about 5 days in the one component model,is an outlier on the R-L relationship as shown in Kaspi et al.(2005);however this problem disappears in our two-component model with lags of about 2 and 6 days for the VBGC and IMGC,respectively.
Huang, Y.; Shao, H.; Thullner, M.; Kolditz, O.
2014-12-01
In applications of Deep Geothermal reservoirs, thermal recovery processes, and contaminated groundwater sites, the multiphase multicomponent flow and transport processes are often considered the most important underlying physical process. In particular, the behavior of phase appearance and disappearance is the critical to the performance of many geo-reservoirs, and great interests exit in the scientific community to simulate this coupled process. This work is devoted to the modeling and simulation of two-phase, two components flow and transport in the porous medium, whereas the phase change behavior in non-isothermal conditions is considered. In this work, we have implemented the algorithm developed by Marchand, et al., into the open source scientific software OpenGeoSys. The governing equation is formulated in terms of molar fraction of the light component and mean pressure as the persistent primary variables, which leads to a fully coupled nonlinear PDE system. One of the important advantages of this approach is avoiding the primary variables switching between single phase and two phase zones, so that this uniform system can be applied to describe the behavior of phase change. On the other hand, due to the number of unkown variables closure relationships are also formulated to close the whole equation system by using the approach of complementarity constrains. For the numerical technical scheme: The standard Galerkin Finite element method is applied for space discretization, while a fully implicit scheme for the time discretization, and Newton-Raphson method is utilized for the global linearization, as well as the closure relationship. This model is verified based on one test case developed to simulate the heat pipe problem. This benchmark involves two-phase two-component flow in saturated/unsaturated porous media under non-isothermal condition, including phase change and mineral-water geochemical reactive transport processes. The simulation results will be
Grasman, J.; Herwaarden, van O.A.; Hemerik, L.; Lenteren, van J.C.
2001-01-01
A two-component differential equation model is formulated for a host–parasitoid interaction. Transient dynamics and population crashes of this system are analysed using differential inequalities. Two different cases can be distinguished: either the intrinsic growth rate of the host population is sma
Indian Academy of Sciences (India)
Debasish Majumdar; Kamakshya Prasad Modak; Subhendu Rakshit
2016-02-01
We propose a two-component dark matter (DM) model, each component of which is a real singlet scalar, to explain results from both direct and indirect detection experiments. We put the constraints on the model parameters from theoretical bounds, PLANCK relic density results and direct DM experiments. The -ray flux is computed from DM annihilation in this framework and is then compared with the Fermi-LAT observations from galactic centre region and Fermi bubble.
Podlaski, Rafał; Roesch, Francis A
2014-03-01
In recent years finite-mixture models have been employed to approximate and model empirical diameter at breast height (DBH) distributions. We used two-component mixtures of either the Weibull distribution or the gamma distribution for describing the DBH distributions of mixed-species, two-cohort forest stands, to analyse the relationships between the DBH components, age cohorts and dominant species, and to assess the significance of differences between the mixture distributions and the kernel density estimates. The data consisted of plots from the Świętokrzyski National Park (Central Poland) and areas close to and including the North Carolina section of the Great Smoky Mountains National Park (USA; southern Appalachians). The fit of the mixture Weibull model to empirical DBH distributions had a precision similar to that of the mixture gamma model, slightly less accurate estimate was obtained with the kernel density estimator. Generally, in the two-cohort, two-storied, multi-species stands in the southern Appalachians, the two-component DBH structure was associated with age cohort and dominant species. The 1st DBH component of the mixture model was associated with the 1st dominant species sp1 occurred in young age cohort (e.g., sweetgum, eastern hemlock); and to a lesser degree, the 2nd DBH component was associated with the 2nd dominant species sp2 occurred in old age cohort (e.g., loblolly pine, red maple). In two-cohort, partly multilayered, stands in the Świętokrzyski National Park, the DBH structure was usually associated with only age cohorts (two dominant species often occurred in both young and old age cohorts). When empirical DBH distributions representing stands of complex structure are approximated using mixture models, the convergence of the estimation process is often significantly dependent on the starting strategies. Depending on the number of DBHs measured, three methods for choosing the initial values are recommended: min.k/max.k, 0.5/1.5/mean
Directory of Open Access Journals (Sweden)
J. P. Kochendorfer
2010-10-01
Full Text Available The statistical-dynamical annual water balance model of Eagleson (1978 is a pioneering work in the analysis of climate, soil and vegetation interactions. This paper describes several enhancements and modifications to the model that improve its physical realism at the expense of its mathematical elegance and analytical tractability. In particular, the analytical solutions for the root zone fluxes are re-derived using separate potential rates of transpiration and bare-soil evaporation. Those potential rates, along with the rate of evaporation from canopy interception, are calculated using the two-component Shuttleworth-Wallace (1985 canopy model. In addition, the soil column is divided into two layers, with the upper layer representing the dynamic root zone. The resulting ability to account for changes in root-zone water storage allows for implementation at the monthly timescale. This new version of the Eagleson model is coined the Statistical-Dynamical Ecohydrology Model (SDEM. The ability of the SDEM to capture the seasonal dynamics of the local-scale soil-water balance is demonstrated for two grassland sites in the US Great Plains. Sensitivity of the results to variations in peak green leaf area index (LAI suggests that the mean peak green LAI is determined by some minimum in root zone soil moisture during the growing season. That minimum appears to be close to the soil matric potential at which the dominant grass species begins to experience water stress and well above the wilting point, thereby suggesting an ecological optimality hypothesis in which the need to avoid water-stress-induced leaf abscission is balanced by the maximization of carbon assimilation (and associated transpiration. Finally, analysis of the sensitivity of model-determined peak green LAI to soil texture shows that the coupled model is able to reproduce the so-called "inverse texture effect", which consists of the observation that natural vegetation in dry climates tends
Directory of Open Access Journals (Sweden)
J. P. Kochendorfer
2008-03-01
Full Text Available The statistical-dynamical annual water balance model of Eagleson (1978 is a pioneering work in the analysis of climate, soil and vegetation interactions. This paper describes several enhancements and modifications to the model that improve its physical realism at the expense of its mathematical elegance and analytical tractability. In particular, the analytical solutions for the root zone fluxes are re-derived using separate potential rates of transpiration and bare-soil evaporation. Those potential rates, along with the rate of evaporation from canopy interception, are calculated using the two-component Shuttleworth-Wallace (1985 canopy model. In addition, the soil column is divided into two layers, with the upper layer representing the dynamic root zone. The resulting ability to account for changes in root-zone water storage allows for implementation at the monthly timescale. This new version of the Eagleson model is coined the Statistical-Dynamical Ecohydrology Model (SDEM. The ability of the SDEM to capture the seasonal dynamics of the local-scale soil-water balance is demonstrated for two grassland sites in the US Great Plains. Sensitivity of the results to variations in peak green Leaf Area Index (LAI suggests that the mean peak green LAI is determined by some minimum in root zone soil moisture during the growing season. That minimum appears to be close to the soil matric potential at which the dominant grass species begins to experience water stress and well above the wilting point, thereby suggesting an ecological optimality hypothesis in which the need to avoid water-stress-induced leaf abscission is balanced by the maximization of carbon assimilation (and associated transpiration. Finally, analysis of the sensitivity of model-determined peak green LAI to soil texture shows that the coupled model is able to reproduce the so-called "inverse texture effect", which consists of the observation that natural vegetation in dry climates tends
Bright, Nathan G.; Carroll, Richard J.; Applegate, Bruce M.
2004-03-01
Microbial contamination has become a mounting concern the last decade due to an increased emphasis of minimally processed food products specifically produce, and the recognition of foodborne pathogens such as Campylobacter jejuni, Escherichia coli O157:H7, and Listeria monocytogenes. This research investigates a detection approach utilizing bacteriophage pathogen specificity coupled with a bacterial bioluminescent bioreporter utilizing the quorum sensing molecule from Vibrio fischeri, N-(3-oxohexanoyl)-homoserine lactone (3-oxo-C6-HSL). The 3-oxo-C6-HSL molecules diffuse out of the target cell after infection and induce bioluminescence from a population of 3-oxo-C6-HSL bioreporters (ROLux). E. coli phage M13, a well-characterized bacteriophage, offers a model system testing the use of bacteriophage for pathogen detection through cell-to-cell communication via a LuxR/3-oxo-C6-HSL system. Simulated temperate phage assays tested functionality of the ROLux reporter and production of 3-oxo-C6-HSL by various test strains. These assays showed detection limits of 102cfu after 24 hours in a varietry of detection formats. Assays incorporating the bacteriophage M13-luxI with the ROLux reporter and a known population of target cells were subsequently developed and have shown consistent detection limits of 105cfu target organisms. Measurable light response from high concentrations of target cells was almost immediate, suggesting an enrichment step to further improve detection limits and reduce assay time.
Directory of Open Access Journals (Sweden)
P.K. Tripathy
2008-07-01
Full Text Available A new type of replenishment policy is suggested in an entropy order quantity model for a perishable product possessing fuzzy holding cost and fuzzy disposal cost. This model represents an appropriate combination of two component demand with discounted selling price, particularly over a finite time horizon. Its main aim lies in the need for an entropic cost of the cycle time is a key feature of specific perishable product like fruits, vegetables, food stuffs, fishes etc. To handle this multiplicity of objectives in a pragmatic approach, entropic ordering quantity model with discounted selling price during pre and post deterioration of perishable items to optimize its payoff is proposed. It has been imperative to demonstrate this model by analysis, which reveals some important characteristics of discounted structure. Furthermore, numerical experiments are conducted to evaluate the difference between the crisp and fuzzy cases in EOQ and EnOQ separately. This paper explores the economy of investing in economics of lot sizing in Fuzzy EOQ, Crisp EOQ and Crisp EnOQ models. The proposed paper reveals itself as a pragmatic alternative to other approaches based on two component demand function with very sound theoretical underpinnings but with few possibilities of actually being put into practice. The results indicate that this can become a good model and can be replicated by researchers in neighbourhood of its possible extensions.
Directory of Open Access Journals (Sweden)
Bhanupriya Dash
2017-09-01
Full Text Available Background: Replenishment policy for entropic order quantity model with two component demand and partial backlogging under inflation is an important subject in the stock management. Methods: In this paper an inventory model for non-instantaneous deteriorating items with stock dependant consumption rate and partial back logged in addition the effect of inflection and time value of money on replacement policy with zero lead time consider was developed. Profit maximization model is formulated by considering the effects of partial backlogging under inflation with cash discounts. Further numerical example presented to evaluate the relative performance between the entropic order quantity and EOQ models separately. Numerical example is present to demonstrate the developed model and to illustrate the procedure. Lingo 13.0 version software used to derive optimal order quantity and total cost of inventory. Finally sensitivity analysis of the optimal solution with respect to different parameters of the system carried out. Results and conclusions: The obtained inventory model is very useful in retail business. This model can extend to total backorder.
Wiengarten, Tobias; Engelbrecht, Eugene; Fichtner, Horst; Kleimann, Jens; Scherer, Klaus
2016-01-01
We extend a two-component model for the evolution of fluctuations in the solar wind plasma so that it is fully three-dimensional (3D) and also coupled self-consistently to the large-scale magnetohydrodynamic (MHD) equations describing the background solar wind. The two classes of fluctuations considered are a high-frequency parallel-propagating wave-like piece and a low-frequency quasi-two-dimensional component. For both components, the nonlinear dynamics is dominanted by quasi-perpendicular spectral cascades of energy. Driving of the fluctuations, by, for example, velocity shear and pickup ions, is included. Numerical solutions to the new model are obtained using the Cronos framework, and validated against previous simpler models. Comparing results from the new model with spacecraft measurements, we find improved agreement relative to earlier models that employ prescribed background solar wind fields. Finally, the new results for the wave-like and quasi-two-dimensional fluctuations are used to calculate ab i...
Energy Technology Data Exchange (ETDEWEB)
Pegos, V.R. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil); Oliveira, P.S.L.; Balan, A. [Laboratorio Nacional de Biociencias - LNBIO, Campinas, SP (Brazil)
2012-07-01
Full text: In Xanthomonas citri, the phytopathogen responsible for the canker citrus disease, we identified in the ssuABCDE operon, genes encoding the alkanesulfonate ABC transporter as well as the two enzymes responsible for oxido reduction of the respective substrates. SsuD and SsuE proteins represent a two-component system that can be assigned to the group of FMNH{sub 2} -dependent monooxygenases. How- ever, despite of the biochemical information about SsuD and SsuE orthologs from Escherichia coli, there is no structural information of how the two proteins work together. In this work, we used ultracentrifugation, SAXS data and molecular modeling to construct a structural/functional model, which consists of eight molecules organized in a weathervane shape. Through this model, SsuD ligand-binding site for NADPH{sub 2} and FMN substrates is clearly exposed, in a way that might allow the protein-protein interactions with SsuE. Moreover, based on molecular dynamics simulations of SsuD in apo state, docked with NADPH{sub 2}, FMN or both substrates, we characterized the residues of the pocket, the mechanism of substrate interaction and transfer of electrons from NADPH{sub 2} to FMN. This is the first report that links functional and biochemical data with structural analyses. (author)
Shimizu, Kei; Saal, Alberto E.; Myers, Corinne E.; Nagle, Ashley N.; Hauri, Erik H.; Forsyth, Donald W.; Kamenetsky, Vadim S.; Niu, Yaoling
2016-03-01
We report major, trace, and volatile element (CO2, H2O, F, Cl, S) contents and Sr, Nd, and Pb isotopes of mid-ocean ridge basalt (MORB) glasses from the Northern East Pacific Rise (NEPR) off-axis seamounts, the Quebrada-Discovery-GoFar (QDG) transform fault system, and the Macquarie Island. The incompatible trace element (ITE) contents of the samples range from highly depleted (DMORB, Th/La ⩽ 0.035) to enriched (EMORB, Th/La ⩾ 0.07), and the isotopic composition spans the entire range observed in EPR MORB. Our data suggest that at the time of melt generation, the source that generated the EMORB was essentially peridotitic, and that the composition of NMORB might not represent melting of a single upper mantle source (DMM), but rather mixing of melts from a two-component mantle (depleted and enriched DMM or D-DMM and E-DMM, respectively). After filtering the volatile element data for secondary processes (degassing, sulfide saturation, assimilation of seawater-derived component, and fractional crystallization), we use the volatiles to ITE ratios of our samples and a two-component mantle melting-mixing model to estimate the volatile content of the D-DMM (CO2 = 22 ppm, H2O = 59 ppm, F = 8 ppm, Cl = 0.4 ppm, and S = 100 ppm) and the E-DMM (CO2 = 990 ppm, H2O = 660 ppm, F = 31 ppm, Cl = 22 ppm, and S = 165 ppm). Our two-component mantle melting-mixing model reproduces the kernel density estimates (KDE) of Th/La and 143Nd/144Nd ratios for our samples and for EPR axial MORB compiled from the literature. This model suggests that: (1) 78% of the Pacific upper mantle is highly depleted (D-DMM) while 22% is enriched (E-DMM) in volatile and refractory ITE, (2) the melts produced during variable degrees of melting of the E-DMM controls most of the MORB geochemical variation, and (3) a fraction (∼65% to 80%) of the low degree EMORB melts (produced by ∼1.3% melting) may escape melt aggregation by freezing at the base of the oceanic lithosphere, significantly enriching it in
Institute of Scientific and Technical Information of China (English)
Yan Jing; Shan Lei; Wang Yue; Xiao Zhi-Li; Wen Hai-Hu
2008-01-01
Low-temperature specific heat in a dichalcogenide superconductor 2H-NbSe2 is measured in various magnetic fields. It is found that the specific heat can be described very well by a simple model concerning two components corresponding to vortex normal core and ambient superconducting region, separately. For calculating the specific heat outside the vortex core region, we use the Bardeen-Cooper-Schrieffer (BCS) formalism under the assumption of a narrow distribution of the superconducting gaps. The field-dependent vortex core size in the mixed state of 2H-NbSe2, determined by using this model, can explain the nonlinear field dependence of specific heat coefficient γ(H), which is in good agreement with the previous experimental results and more formal calculations. With the high-temperature specific heat data, we can find that, in the multi-band superconductor 2H-NbSe2, the recovered density of states (or Fermi surface) below Tc under a magnetic field seems not to be gapped again by the charge density wave (CDW) gap, which suggests that the superconducting gap and the CDW gap may open on different Fermi surface sheets.
Di Paola, Vieri; Marijuán, Pedro C; Lahoz-Beltra, Rafael
2004-01-01
Adaptive behavior in unicellular organisms (i.e., bacteria) depends on highly organized networks of proteins governing purposefully the myriad of molecular processes occurring within the cellular system. For instance, bacteria are able to explore the environment within which they develop by utilizing the motility of their flagellar system as well as a sophisticated biochemical navigation system that samples the environmental conditions surrounding the cell, searching for nutrients or moving away from toxic substances or dangerous physical conditions. In this paper we discuss how proteins of the intervening signal transduction network could be modeled as artificial neurons, simulating the dynamical aspects of the bacterial taxis. The model is based on the assumption that, in some important aspects, proteins can be considered as processing elements or McCulloch-Pitts artificial neurons that transfer and process information from the bacterium's membrane surface to the flagellar motor. This simulation of bacterial taxis has been carried out on a hardware realization of a McCulloch-Pitts artificial neuron using an operational amplifier. Based on the behavior of the operational amplifier we produce a model of the interaction between CheY and FliM, elements of the prokaryotic two component system controlling chemotaxis, as well as a simulation of learning and evolution processes in bacterial taxis. On the one side, our simulation results indicate that, computationally, these protein 'switches' are similar to McCulloch-Pitts artificial neurons, suggesting a bridge between evolution and learning in dynamical systems at cellular and molecular levels and the evolutive hardware approach. On the other side, important protein 'tactilizing' properties are not tapped by the model, and this suggests further complexity steps to explore in the approach to biological molecular computing.
Directory of Open Access Journals (Sweden)
Rebecca B Hoyle
Full Text Available Phenotypic differences of genetically identical cells under the same environmental conditions have been attributed to the inherent stochasticity of biochemical processes. Various mechanisms have been suggested, including the existence of alternative steady states in regulatory networks that are reached by means of stochastic fluctuations, long transient excursions from a stable state to an unstable excited state, and the switching on and off of a reaction network according to the availability of a constituent chemical species. Here we analyse a detailed stochastic kinetic model of two-component system signalling in bacteria, and show that alternative phenotypes emerge in the absence of these features. We perform a bifurcation analysis of deterministic reaction rate equations derived from the model, and find that they cannot reproduce the whole range of qualitative responses to external signals demonstrated by direct stochastic simulations. In particular, the mixed mode, where stochastic switching and a graded response are seen simultaneously, is absent. However, probabilistic and equation-free analyses of the stochastic model that calculate stationary states for the mean of an ensemble of stochastic trajectories reveal that slow transcription of either response regulator or histidine kinase leads to the coexistence of an approximate basal solution and a graded response that combine to produce the mixed mode, thus establishing its essential stochastic nature. The same techniques also show that stochasticity results in the observation of an all-or-none bistable response over a much wider range of external signals than would be expected on deterministic grounds. Thus we demonstrate the application of numerical equation-free methods to a detailed biochemical reaction network model, and show that it can provide new insight into the role of stochasticity in the emergence of phenotypic diversity.
Odille, Fabrice G J; Jónsson, Stefán; Stjernqvist, Susann; Rydén, Tobias; Wärnmark, Kenneth
2007-01-01
A general mathematical model for the characterization of the dynamic (kinetically labile) association of supramolecular assemblies in solution is presented. It is an extension of the equal K (EK) model by the stringent use of linear algebra to allow for the simultaneous presence of an unlimited number of different units in the resulting assemblies. It allows for the analysis of highly complex dynamic equilibrium systems in solution, including both supramolecular homo- and copolymers without the recourse to extensive approximations, in a field in which other analytical methods are difficult. The derived mathematical methodology makes it possible to analyze dynamic systems such as supramolecular copolymers regarding for instance the degree of polymerization, the distribution of a given monomer in different copolymers as well as its position in an aggregate. It is to date the only general means to characterize weak supramolecular systems. The model was fitted to NMR dilution titration data by using the program Matlab, and a detailed algorithm for the optimization of the different parameters has been developed. The methodology is applied to a case study, a hydrogen-bonded supramolecular system, salen 4+porphyrin 5. The system is formally a two-component system but in reality a three-component system. This results in a complex dynamic system in which all monomers are associated to each other by hydrogen bonding with different association constants, resulting in homo- and copolymers 4n5m as well as cyclic structures 6 and 7, in addition to free 4 and 5. The system was analyzed by extensive NMR dilution titrations at variable temperatures. All chemical shifts observed at different temperatures were used in the fitting to obtain the DeltaH degrees and DeltaS degrees values producing the best global fit. From the derived general mathematical expressions, system 4+5 could be characterized with respect to above-mentioned parameters.
Two component theory and electron magnetic moment
Veltman, M.J.G.
1998-01-01
The two-component formulation of quantum electrodynamics is studied. The relation with the usual Dirac formulation is exhibited, and the Feynman rules for the two-component form of the theory are presented in terms of familiar objects. The transformation from the Dirac theory to the two-component th
Two component theory and electron magnetic moment
Veltman, M.J.G.
1998-01-01
The two-component formulation of quantum electrodynamics is studied. The relation with the usual Dirac formulation is exhibited, and the Feynman rules for the two-component form of the theory are presented in terms of familiar objects. The transformation from the Dirac theory to the two-component
Two-component Duality and Strings
Freund, Peter G O
2007-01-01
A phenomenologically successful two-component hadronic duality picture led to Veneziano's amplitude, the fundamental first step to string theory. This picture is briefly recalled and its two components are identified as the open strings (mesons and baryons) and closed strings (Pomeron).
Model-based analysis of thermal insulation coatings
DEFF Research Database (Denmark)
Kiil, Søren
2014-01-01
Thermal insulation properties of coatings based on selected functional filler materials are investigated. The underlying physics, thermal conductivity of a heterogeneous two-component coating, and porosity and thermal conductivity of hollow spheres (HS) are quantified and a mathematical model...... for a thermal insulation coating developed. Data from a previous experimental investigation with hollow glass sphere-based epoxy and acrylic coatings were used for model validation. Simulations of thermal conductivities were in good agreement with experimental data. Using the model, a parameter study was also...... conducted exploring the effects of the following parameters: pigment (hollow spheres) volume concentration (PVC), average sphere size or sphere size distribution, thermal conductivities of binder and sphere wall material, and sphere wall thickness. All the parameters affected the thermal conductivity...
Bauer, Hannes R.; Kirkman, George; Gundersen, Martin A.
1990-04-01
Temperature, energy, and densities of two electron distribution function components, including an isotropic bulk part and an anisotropic beam, are analyzed for a hydrogen pseudospark and/or backlighted thyratron switch plasma with a peak electron density of 1-3 x 10 to the 15th/cu cm and peak current density of about 10 kA/sq cm. Estimates of a very small cathode-fall width during the conduction phase and high electric field strengths lead to the injection of an electron beam with energies of about 100 eV and density (1-10) x 10 to the 13th/cu cm into a Maxwellian bulk plasma. Collisional and radiative processes of monoenergetic beam electrons, bulk plasma electrons and ions, and atomic hydrogen are modeled by a set of rate equations, and line intensity ratios are compared with measurements. Under these high-current conditions, for an initial density nH2 = 10 to the 16th/cu cm and electron temperature of 0.8-1 eV, the estimated beam density is about (1-10) x 10 to the 13th/cu cm.
Energy Technology Data Exchange (ETDEWEB)
Herrou, Julien; Foreman, Robert; Fiebig, Aretha; Crosson, Sean (UC)
2012-05-09
PhyR is a hybrid stress regulator conserved in {alpha}-proteobacteria that contains an N-terminal {sigma}-like (SL) domain and a C-terminal receiver domain. Phosphorylation of the receiver domain is known to promote binding of the SL domain to an anti-{sigma} factor. PhyR thus functions as an anti-anti-{sigma} factor in its phosphorylated state. We present genetic evidence that Caulobacter crescentus PhyR is a phosphorylation-dependent stress regulator that functions in the same pathway as {sigma}{sup T} and its anti-{sigma} factor, NepR. Additionally, we report the X-ray crystal structure of PhyR at 1.25 {angstrom} resolution, which provides insight into the mechanism of anti-anti-{sigma} regulation. Direct intramolecular contact between the PhyR receiver and SL domains spans regions {sigma}{sub 2} and {sigma}{sub 4}, likely serving to stabilize the SL domain in a closed conformation. The molecular surface of the receiver domain contacting the SL domain is the structural equivalent of {alpha}4-{beta}5-{alpha}5, which is known to undergo dynamic conformational change upon phosphorylation in a diverse range of receiver proteins. We propose a structural model of PhyR regulation in which receiver phosphorylation destabilizes the intramolecular interaction between SL and receiver domains, thereby permitting regions {sigma}{sub 2} and {sigma}{sub 4} in the SL domain to open about a flexible connector loop and bind anti-{sigma} factor.
Energy Technology Data Exchange (ETDEWEB)
Herrou, Julien; Foreman, Robert; Fiebig, Aretha; Crosson, Sean (UC)
2012-03-30
PhyR is a hybrid stress regulator conserved in {alpha}-proteobacteria that contains an N-terminal {sigma}-like (SL) domain and a C-terminal receiver domain. Phosphorylation of the receiver domain is known to promote binding of the SL domain to an anti-{sigma} factor. PhyR thus functions as an anti-anti-{sigma} factor in its phosphorylated state. We present genetic evidence that Caulobacter crescentus PhyR is a phosphorylation-dependent stress regulator that functions in the same pathway as {sigma}{sup T} and its anti-{sigma} factor, NepR. Additionally, we report the X-ray crystal structure of PhyR at 1.25 {angstrom} resolution, which provides insight into the mechanism of anti-anti-{sigma} regulation. Direct intramolecular contact between the PhyR receiver and SL domains spans regions {sigma}{sub 2} and {sigma}{sub 4}, likely serving to stabilize the SL domain in a closed conformation. The molecular surface of the receiver domain contacting the SL domain is the structural equivalent of {alpha}4-{beta}5-{alpha}5, which is known to undergo dynamic conformational change upon phosphorylation in a diverse range of receiver proteins. We propose a structural model of PhyR regulation in which receiver phosphorylation destabilizes the intramolecular interaction between SL and receiver domains, thereby permitting regions {sigma}{sub 2} and {sigma}{sub 4} in the SL domain to open about a flexible connector loop and bind anti-{sigma} factor.
Modeling Thermal Contact Resistance
Kittel, Peter; Sperans, Joel (Technical Monitor)
1994-01-01
One difficulty in using cryocoolers is making good thermal contact between the cooler and the instrument being cooled. The connection is often made through a bolted joint. The temperature drop associated with this joint has been the subject of many experimental and theoretical studies. The low temperature behavior of dry joints have shown some anomalous dependence on the surface condition of the mating parts. There is also some doubts on how well one can extrapolate from the test samples to predicting the performance of a real system. Both finite element and analytic models of a simple contact system have been developed. The model assumes (a) the contact is dry (contact limited to a small portion of the total available area and the spaces in-between the actual contact patches are perfect insulators), (b) contacts are clean (conductivity of the actual contact is the same as the bulk), (c) small temperature gradients (the bulk conductance may be assumed to be temperature independent), (d) the absolute temperature is low (thermal radiation effects are ignored), and (e) the dimensions of the nominal contact area are small compared to the thickness of the bulk material (the contact effects are localized near the contact). The models show that in the limit of actual contact area much less than the nominal area (a much less than A), that the excess temperature drop due to a single point of contact scales as a(exp -1/2). This disturbance only extends a distance approx. A(exp 1/2) into the bulk material. A group of identical contacts will result in an excess temperature drop that scales as n(exp -1/2), where n is the number of contacts and n dot a is constant. This implies that flat rough surfaces will have a lower excess temperature drop than flat polished surfaces.
Goal-Directed Aiming: Two Components but Multiple Processes
Elliott, Digby; Hansen, Steve; Grierson, Lawrence E. M.; Lyons, James; Bennett, Simon J.; Hayes, Spencer J.
2010-01-01
This article reviews the behavioral literature on the control of goal-directed aiming and presents a multiple-process model of limb control. The model builds on recent variants of Woodworth's (1899) two-component model of speed-accuracy relations in voluntary movement and incorporates ideas about dynamic online limb control based on prior…
Inhibitors targeting two-component signal transduction.
Watanabe, Takafumi; Okada, Ario; Gotoh, Yasuhiro; Utsumi, Ryutaro
2008-01-01
A two-component signal transduction system (TCS) is an attractive target for antibacterial agents. In this chapter, we review the TCS inhibitors developed during the past decade and introduce novel drug discovery systems to isolate the inhibitors of the YycG/YycF system, an essential TCS for bacterial growth, in an effort to develop a new class of antibacterial agents.
Thermal modeling environment for TMT
Vogiatzis, Konstantinos
2010-01-01
In a previous study we had presented a summary of the TMT Aero-Thermal modeling effort to support thermal seeing and dynamic loading estimates. In this paper a summary of the current status of Computational Fluid Dynamics (CFD) simulations for TMT is presented, with the focus shifted in particular towards the synergy between CFD and the TMT Finite Element Analysis (FEA) structural and optical models, so that the thermal and consequent optical deformations of the telescope can be calculated. T...
Powerplant Thermal-Pollution Models
Lee, S. S.; Sengupta, S.
1982-01-01
Three models predict nature of thermal plumes from powerplant discharge into water. Free-surface model accomodates major changes in ocean currents. Rigid-model accurately predicts changes in thermal plume caused by other inputs and outputs, such as pumped-water storage and hydroelectric-plant discharges. One-dimensional model predicts approximate stratification in lake with such inputs and outputs over a long period.
Powerplant Thermal-Pollution Models
Lee, S. S.; Sengupta, S.
1982-01-01
Three models predict nature of thermal plumes from powerplant discharge into water. Free-surface model accomodates major changes in ocean currents. Rigid-model accurately predicts changes in thermal plume caused by other inputs and outputs, such as pumped-water storage and hydroelectric-plant discharges. One-dimensional model predicts approximate stratification in lake with such inputs and outputs over a long period.
Thermal modeling of stratospheric airships
Wu, Jiangtao; Fang, Xiande; Wang, Zhenguo; Hou, Zhongxi; Ma, Zhenyu; Zhang, Helei; Dai, Qiumin; Xu, Yu
2015-05-01
The interest in stratospheric airships has increased and great progress has been achieved since the late 1990s due to the advancement of modern techniques and the wide range of application demands in military, commercial, and scientific fields. Thermal issues are challenging for stratospheric airships, while there is no systematic review on this aspect found yet. This paper presents a comprehensive literature review on thermal issues of stratospheric airships. The main challenges of thermal issues on stratospheric airships are analyzed. The research activities and results on the main thermal issues are surveyed, including solar radiation models, environmental longwave radiation models, external convective heat transfer, and internal convective heat transfer. Based on the systematic review, guides for thermal model selections are provided, and topics worthy of attention for future research are suggested.
A 100-3000 GHz model of thermal dust emission observed by Planck, DIRBE and IRAS
Meisner, Aaron M.; Finkbeiner, Douglas P.
2015-01-01
We apply the Finkbeiner et al. (1999) two-component thermal dust emission model to the Planck HFI maps. This parametrization of the far-infrared dust spectrum as the sum of two modified blackbodies serves as an important alternative to the commonly adopted single modified blackbody (MBB) dust emission model. Analyzing the joint Planck/DIRBE dust spectrum, we show that two-component models provide a better fit to the 100-3000 GHz emission than do single-MBB models, though by a lesser margin than found by Finkbeiner et al. (1999) based on FIRAS and DIRBE. We also derive full-sky 6.1' resolution maps of dust optical depth and temperature by fitting the two-component model to Planck 217-857 GHz along with DIRBE/IRAS 100μm data. Because our two-component model matches the dust spectrum near its peak, accounts for the spectrum's flattening at millimeter wavelengths, and specifies dust temperature at 6.1' FWHM, our model provides reliable, high-resolution thermal dust emission foreground predictions from 100 to 3000 GHz. We find that, in diffuse sky regions, our two-component 100-217 GHz predictions are on average accurate to within 2.2%, while extrapolating the Planck Collaboration (2013) single-MBB model systematically underpredicts emission by 18.8% at 100 GHz, 12.6% at 143 GHz and 7.9% at 217 GHz. We calibrate our two-component optical depth to reddening, and compare with reddening estimates based on stellar spectra. We find the dominant systematic problems in our temperature/reddening maps to be zodiacal light on large angular scales and the cosmic infrared background anistropy on small angular scales. We have recently released maps and associated software utilities for obtaining thermal dust emission and reddening predictions using our Planck-based two-component model.
Two Component Signal Transduction in Desulfovibrio Species
Energy Technology Data Exchange (ETDEWEB)
Luning, Eric; Rajeev, Lara; Ray, Jayashree; Mukhopadhyay, Aindrila
2010-05-17
The environmentally relevant Desulfovibrio species are sulfate-reducing bacteria that are of interest in the bioremediation of heavy metal contaminated water. Among these, the genome of D. vulgaris Hildenborough encodes a large number of two component systems consisting of 72 putative response regulators (RR) and 64 putative histidinekinases (HK), the majority of which are uncharacterized. We classified the D. vulgaris Hildenborough RRs based on their output domains and compared the distribution of RRs in other sequenced Desulfovibrio species. We have successfully purified most RRs and several HKs as His-tagged proteins. We performed phospho-transfer experiments to verify relationships between cognate pairs of HK and RR, and we have also mapped a few non-cognate HK-RR pairs. Presented here are our discoveries from the Desulfovibrio RR categorization and results from the in vitro studies using purified His tagged D. vulgaris HKs and RRs.
Two-Component Description for Relativistic Fermions
Institute of Scientific and Technical Information of China (English)
CHEN Yu-Qi; SANG Wen-Long; YANG Lan-Fei
2009-01-01
We propose a two-component form to describe massive relativistic fermions in gauge theories. Relations between the Green's functions in this form and those in the conventional four-component form are derived. It is shown that the S-matrix elements in both forms are exactly the same. The description of the fermion in the new form simplifies significantly the γ-matrix algebra in the four-component form. In particular, in perturbative calculations the propagator of the fermion is a scalar function. As examples, we use this form to reproduce the relativistic spectrum of hydrodron atom, the S-matrix of e+ e-→μ+ μ- and QED one-loop vacuum polarization of photon.
Advanced Spacecraft Thermal Modeling Project
National Aeronautics and Space Administration — For spacecraft developers who spend millions to billions of dollars per unit and require 3 to 7 years to deploy, the LoadPath reduced-order (RO) modeling thermal...
Lumped Thermal Household Model
DEFF Research Database (Denmark)
Biegel, Benjamin; Andersen, Palle; Stoustrup, Jakob
2013-01-01
a lumped model approach as an alternative to the individual models. In the lumped model, the portfolio is seen as baseline consumption superimposed with an ideal storage of limited power and energy capacity. The benefit of such a lumped model is that the computational effort of flexibility optimization......In this paper we discuss two different approaches to model the flexible power consumption of heat pump heated households: individual household modeling and lumped modeling. We illustrate that a benefit of individual modeling is that we can overview and optimize the complete flexibility of a heat...... pump portfolio. Following, we illustrate two disadvantages of individual models, namely that it requires much computational effort to optimize over a large portfolio, and second that it is difficult to accurately model the houses in certain time periods due to local disturbances. Finally, we propose...
Thermal modeling environment for TMT
Vogiatzis, Konstantinos
2010-07-01
In a previous study we had presented a summary of the TMT Aero-Thermal modeling effort to support thermal seeing and dynamic loading estimates. In this paper a summary of the current status of Computational Fluid Dynamics (CFD) simulations for TMT is presented, with the focus shifted in particular towards the synergy between CFD and the TMT Finite Element Analysis (FEA) structural and optical models, so that the thermal and consequent optical deformations of the telescope can be calculated. To minimize thermal deformations and mirror seeing the TMT enclosure will be air conditioned during day-time to the expected night-time ambient temperature. Transient simulations with closed shutter were performed to investigate the optimum cooling configuration and power requirements for the standard telescope parking position. A complete model of the observatory on Mauna Kea was used to calculate night-time air temperature inside the enclosure (along with velocity and pressure) for a matrix of given telescope orientations and enclosure configurations. Generated records of temperature variations inside the air volume of the optical paths are also fed into the TMT thermal seeing model. The temperature and heat transfer coefficient outputs from both models are used as input surface boundary conditions in the telescope structure and optics FEA models. The results are parameterized so that sequential records several days long can be generated and used by the FEA model to estimate the observing spatial and temporal temperature range of the structure and optics.
Tobacco two-component gene NTHK2
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
By using a previously isolated tobacco two- component gene NTHK1 as a probe, we screened a cDNA library and obtained a homologous gene designated NTHK2. Sequencing analysis revealed that NTHK2 encoded a putative ethylene receptor homolog and contained a histidine kinase domain and a receiver domain. In the histidine kinase domain, the histidine at the phosphorylation site was replaced by an asparagine. Southern analysis indicated that NTHK2 was present at low copies in tobacco genome. The expression of NTHK2 was studied using a competitive RT-PCR method. It was found that, in young flower buds, NTHK2 was expressed abundantly, while in other organs or tissues, it was expressed in a low level. When leaf was subjected to wounding (cutting) treatment, NTHK2 expression was increased. When tobacco seedlings were stressed with PEG and heat shock, NTHK2 transcription was also enhanced. Other treatments showed little effects. These results indicated that NTHK2 might be involved in the developmental processes and in plant responses to some environmental stresses.
Selected soil thermal conductivity models
Directory of Open Access Journals (Sweden)
Rerak Monika
2017-01-01
Full Text Available The paper presents collected from the literature models of soil thermal conductivity. This is a very important parameter, which allows one to assess how much heat can be transferred from the underground power cables through the soil. The models are presented in table form, thus when the properties of the soil are given, it is possible to select the most accurate method of calculating its thermal conductivity. Precise determination of this parameter results in designing the cable line in such a way that it does not occur the process of cable overheating.
An Analytic Model Of Thermal Drift In Piezoresistive Microcantilever Sensors
Energy Technology Data Exchange (ETDEWEB)
Loui, A; Elhadj, S; Sirbuly, D J; McCall, S K; Hart, B R; Ratto, T V
2009-08-26
A closed form semi-empirical model has been developed to understand the physical origins of thermal drift in piezoresistive microcantilever sensors. The two-component model describes both the effects of temperature-related bending and heat dissipation on the piezoresistance. The temperature-related bending component is based on the Euler-Bernoulli theory of elastic deformation applied to a multilayer cantilever. The heat dissipation component is based on energy conservation per unit time for a piezoresistive cantilever in a Wheatstone bridge circuit, representing a balance between electrical power input and heat dissipation into the environment. Conduction and convection are found to be the primary mechanisms of heat transfer, and the dependence of these effects on the thermal conductivity, temperature, and flow rate of the gaseous environment is described. The thermal boundary layer value which defines the length scale of the heat dissipation phenomenon is treated as an empirical fitting parameter. Using the model, it is found that the cantilever heat dissipation is unaffected by the presence of a thin polymer coating, therefore the residual thermal drift in the differential response of a coated and uncoated cantilever is the result of non-identical temperature-related bending. Differential response data shows that residual drift is eliminated under isothermal laboratory conditions but not the unregulated and variable conditions that exist in the outdoor environment (i.e., the field). The two-component model is then validated by simulating the thermal drifts of an uncoated and a coated piezoresistive cantilever under field conditions over a 24 hour period using only meteorological data as input.
Energy Technology Data Exchange (ETDEWEB)
Band, D.L.
1986-12-01
The infrared, optical and x-ray continua from radio quiet active galactic nuclei (AGN) are explained by a compact non-thermal source surrounding a thermal ultraviolet emitter, presumably the accretion disk around a supermassive black hole. The ultraviolet source is observed as the ''big blue bump.'' The flat (..cap alpha.. approx. = .7) hard x-ray spectrum results from the scattering of thermal ultraviolet photons by the flat, low energy end of an electron distribution ''broken'' by Compton losses; the infrared through soft x-ray continuum is the synchrotron radiation of the steep, high energy end of the electron distribution. Quantitative fits to specific AGN result in models which satisfy the variability constraints but require electron (re)acceleration throughout the source. 11 refs., 1 fig.
Graphene Oxide: A One- versus Two-Component Material.
Naumov, Anton; Grote, Fabian; Overgaard, Marc; Roth, Alexandra; Halbig, Christian E; Nørgaard, Kasper; Guldi, Dirk M; Eigler, Siegfried
2016-09-14
The structure of graphene oxide (GO) is a matter of discussion. While established GO models are based on functional groups attached to the carbon framework, another frequently used model claims that GO consists of two components, a slightly oxidized graphene core and highly oxidized molecular species, oxidative debris (OD), adsorbed on it. Those adsorbents are claimed to be the origin for optical properties of GO. Here, we examine this model by preparing GO with a low degree of functionalization, combining it with OD and studying the optical properties of both components and their combination in an artificial two-component system. The analyses of absorption and emission spectra as well as lifetime measurements reveal that properties of the combined system are distinctly different from those of GO. That confirms structural models of GO as a separate oxygenated hexagonal carbon framework with optical properties governed by its internal structure rather than the presence of OD. Understanding the structure of GO allows further reliable interpretation of its optical and electronic properties and enables controlled processing of GO.
TASI 2011 lectures notes: two-component fermion notation and supersymmetry
Martin, Stephen P.
2012-01-01
These notes, based on work with Herbi Dreiner and Howie Haber, discuss how to do practical calculations of cross sections and decay rates using two-component fermion notation, as appropriate for supersymmetry and other beyond-the-Standard-Model theories. Included are a list of two-component fermion Feynman rules for the Minimal Supersymmetric Standard Model, and some example calculations.
Helical coil thermal hydraulic model
Caramello, M.; Bertani, C.; De Salve, M.; Panella, B.
2014-11-01
A model has been developed in Matlab environment for the thermal hydraulic analysis of helical coil and shell steam generators. The model considers the internal flow inside one helix and its associated control volume of water on the external side, both characterized by their inlet thermodynamic conditions and the characteristic geometry data. The model evaluates the behaviour of the thermal-hydraulic parameters of the two fluids, such as temperature, pressure, heat transfer coefficients, flow quality, void fraction and heat flux. The evaluation of the heat transfer coefficients as well as the pressure drops has been performed by means of the most validated literature correlations. The model has been applied to one of the steam generators of the IRIS modular reactor and a comparison has been performed with the RELAP5/Mod.3.3 code applied to an inclined straight pipe that has the same length and the same elevation change between inlet and outlet of the real helix. The predictions of the developed model and RELAP5/Mod.3.3 code are in fairly good agreement before the dryout region, while the dryout front inside the helical pipes is predicted at a lower distance from inlet by the model.
No electrostatic supersolitons in two-component plasmas
Energy Technology Data Exchange (ETDEWEB)
Verheest, Frank, E-mail: frank.verheest@ugent.be [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, B–9000 Gent (Belgium); School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa); Lakhina, Gurbax S., E-mail: lakhina@iigm.iigs.res.in [Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai (India); Hellberg, Manfred A., E-mail: hellberg@ukzn.ac.za [School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa)
2014-06-15
The concept of acoustic supersolitons was introduced for a very specific plasma with five constituents, and discussed only for a single set of plasma parameters. Supersolitons are characterized by having subsidiary extrema on the sides of a typical bipolar electric field signature, or by association with a root beyond double layers in the fully nonlinear Sagdeev pseudopotential description. It was subsequently found that supersolitons could exist in several plasma models having three constituent species, rather than four or five. In the present paper, it is proved that standard two-component plasma models cannot generate supersolitons, by recalling and extending results already in the literature, and by establishing the necessary properties of a more recent model.
Human Thermal Model Evaluation Using the JSC Human Thermal Database
Bue, Grant; Makinen, Janice; Cognata, Thomas
2012-01-01
Human thermal modeling has considerable long term utility to human space flight. Such models provide a tool to predict crew survivability in support of vehicle design and to evaluate crew response in untested space environments. It is to the benefit of any such model not only to collect relevant experimental data to correlate it against, but also to maintain an experimental standard or benchmark for future development in a readily and rapidly searchable and software accessible format. The Human thermal database project is intended to do just so; to collect relevant data from literature and experimentation and to store the data in a database structure for immediate and future use as a benchmark to judge human thermal models against, in identifying model strengths and weakness, to support model development and improve correlation, and to statistically quantify a model s predictive quality. The human thermal database developed at the Johnson Space Center (JSC) is intended to evaluate a set of widely used human thermal models. This set includes the Wissler human thermal model, a model that has been widely used to predict the human thermoregulatory response to a variety of cold and hot environments. These models are statistically compared to the current database, which contains experiments of human subjects primarily in air from a literature survey ranging between 1953 and 2004 and from a suited experiment recently performed by the authors, for a quantitative study of relative strength and predictive quality of the models.
W-320 Project thermal modeling
Energy Technology Data Exchange (ETDEWEB)
Sathyanarayana, K., Fluor Daniel Hanford
1997-03-18
This report summarizes the results of thermal analysis performed to provide a technical basis in support of Project W-320 to retrieve by sluicing the sludge in Tank 241-C-106 and to transfer into Tank 241-AY-102. Prior theraml evaluations in support of Project W-320 safety analysis assumed the availability of 2000 to 3000 CFM, as provided by Tank Farm Operations, for tank floor cooling channels from the secondary ventilation system. As this flow availability has no technical basis, a detailed Tank 241-AY-102 secondary ventilation and floor coating channel flow model was developed and analysis was performed. The results of the analysis show that only about 150 cfm flow is in floor cooLing channels. Tank 241-AY-102 thermal evaluation was performed to determine the necessary cooling flow for floor cooling channels using W-030 primary ventilation system for different quantities of Tank 241-C-106 sludge transfer into Tank 241-AY-102. These sludge transfers meet different options for the project along with minimum required modification of the ventilation system. Also the results of analysis for the amount of sludge transfer using the current system is presented. The effect of sludge fluffing factor, heat generation rate and its distribution between supernatant and sludge in Tank 241-AY-102 on the amount of sludge transfer from Tank 241-C-106 were evaluated and the results are discussed. Also transient thermal analysis was performed to estimate the time to reach the steady state. For a 2 feet sludge transfer, about 3 months time will be requirad to reach steady state. Therefore, for the purpose of process control, a detailed transient thermal analysis using GOTH Computer Code will be required to determine transient response of the sludge in Tank 241-AY-102. Process control considerations are also discussed to eliminate the potential for a steam bump during retrieval and storage in Tanks 241-C-106 and 241-AY-102 respectively.
Battery thermal models for hybrid vehicle simulations
Pesaran, Ahmad A.
This paper summarizes battery thermal modeling capabilities for: (1) an advanced vehicle simulator (ADVISOR); and (2) battery module and pack thermal design. The National Renewable Energy Laboratory's (NREL's) ADVISOR is developed in the Matlab/Simulink environment. There are several battery models in ADVISOR for various chemistry types. Each one of these models requires a thermal model to predict the temperature change that could affect battery performance parameters, such as resistance, capacity and state of charges. A lumped capacitance battery thermal model in the Matlab/Simulink environment was developed that included the ADVISOR battery performance models. For thermal evaluation and design of battery modules and packs, NREL has been using various computer aided engineering tools including commercial finite element analysis software. This paper will discuss the thermal ADVISOR battery model and its results, along with the results of finite element modeling that were presented at the workshop on "Development of Advanced Battery Engineering Models" in August 2001.
Hamiltonian of a homogeneous two-component plasma.
Essén, Hanno; Nordmark, A
2004-03-01
The Hamiltonian of one- and two-component plasmas is calculated in the negligible radiation Darwin approximation. Since the Hamiltonian is the phase space energy of the system its form indicates, according to statistical mechanics, the nature of the thermal equilibrium that plasmas strive to attain. The main issue is the length scale of the magnetic interaction energy. In the past a screening length lambda=1/square root of r(e)n], with n number density and r(e) classical electron radius, has been derived. We address the question whether the corresponding longer screening range obtained from the classical proton radius is physically relevant and the answer is affirmative. Starting from the Darwin Lagrangian it is nontrivial to find the Darwin Hamiltonian of a macroscopic system. For a homogeneous system we resolve the difficulty by temporarily approximating the particle number density by a smooth constant density. This leads to Yukawa-type screened vector potential. The nontrivial problem of finding the corresponding, divergence free, Coulomb gauge version is solved.
Two-component jet simulations: Combining analytical and numerical approaches
Matsakos, T; Trussoni, E; Tsinganos, K; Vlahakis, N; Sauty, C; Mignone, A
2009-01-01
Recent observations as well as theoretical studies of YSO jets suggest the presence of two steady components: a disk wind type outflow needed to explain the observed high mass loss rates and a stellar wind type outflow probably accounting for the observed stellar spin down. In this framework, we construct numerical two-component jet models by properly mixing an analytical disk wind solution with a complementary analytically derived stellar outflow. Their combination is controlled by both spatial and temporal parameters, in order to address different physical conditions and time variable features. We study the temporal evolution and the interaction of the two jet components on both small and large scales. The simulations reach steady state configurations close to the initial solutions. Although time variability is not found to considerably affect the dynamics, flow fluctuations generate condensations, whose large scale structures have a strong resemblance to observed YSO jet knots.
Efficient two-component relativistic method for large systems
Energy Technology Data Exchange (ETDEWEB)
Nakai, Hiromi [Department of Chemitsry and Biochemistry, School of Advanced Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Elements Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, Katsura, Kyoto 615-8520 (Japan)
2015-12-31
This paper reviews a series of theoretical studies to develop efficient two-component (2c) relativistic method for large systems by the author’s group. The basic theory is the infinite-order Douglas-Kroll-Hess (IODKH) method for many-electron Dirac-Coulomb Hamiltonian. The local unitary transformation (LUT) scheme can effectively produce the 2c relativistic Hamiltonian, and the divide-and-conquer (DC) method can achieve linear-scaling of Hartree-Fock and electron correlation methods. The frozen core potential (FCP) theoretically connects model potential calculations with the all-electron ones. The accompanying coordinate expansion with a transfer recurrence relation (ACE-TRR) scheme accelerates the computations of electron repulsion integrals with high angular momenta and long contractions.
Budding Transition of Asymmetric Two-component Lipid Domains
Wolff, Jean; Andelman, David
2016-01-01
We propose a model that accounts for the budding transition of asymmetric two-component lipid domains, where the two monolayers (leaflets) have different average compositions controlled by independent chemical potentials. Assuming a coupling between the local curvature and local lipid composition in each of the leaflets, we discuss the morphology and thermodynamic behavior of asymmetric lipid domains. The membrane free-energy contains three contributions: the bending energy, the line tension, and a Landau free-energy for a lateral phase separation. Within a mean-field treatment, we obtain various phase diagrams containing fully budded, dimpled, and flat states as a function of the two leaflet compositions. The global phase behavior is analyzed, and depending on system parameters, the phase diagrams include one-phase, two-phase and three-phase regions. In particular, we predict various phase coexistence regions between different morphologies of domains, which may be observed in multi-component membranes or ves...
The mechanism of signal transduction by two-component systems.
Casino, Patricia; Rubio, Vicente; Marina, Alberto
2010-12-01
Two-component systems, composed of a homodimeric histidine kinase (HK) and a response regulator (RR), are major signal transduction devices in bacteria. Typically the signal triggers HK autophosphorylation at one His residue, followed by phosphoryl transfer from the phospho-His to an Asp residue in the RR. Signal extinction frequently involves phospho-RR dephosphorylation by a phosphatase activity of the HK. Our understanding of these reactions and of the determinants of partner specificity among HK-RR couples has been greatly increased by recent crystal structures and biochemical experiments on HK-RR complexes. Cis-autophosphorylation (one subunit phosphorylates itself) occurs in some HKs while trans-autophosphorylation takes place in others. We review and integrate this new information, discuss the mechanism of the three reactions and propose a model for transmembrane signaling by these systems. Copyright © 2010 Elsevier Ltd. All rights reserved.
Supo Thermal Model Development II
Energy Technology Data Exchange (ETDEWEB)
Wass, Alexander Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-07-14
This report describes the continuation of the Computational Fluid Dynamics (CFD) model of the Supo cooling system described in the report, Supo Thermal Model Development1, by Cynthia Buechler. The goal for this report is to estimate the natural convection heat transfer coefficient (HTC) of the system using the CFD results and to compare those results to remaining past operational data. Also, the correlation for determining radiolytic gas bubble size is reevaluated using the larger simulation sample size. The background, solution vessel geometry, mesh, material properties, and boundary conditions are developed in the same manner as the previous report. Although, the material properties and boundary conditions are determined using the appropriate experiment results for each individual power level.
DEFF Research Database (Denmark)
Bahman, Amir Sajjad; Ma, Ke; Blaabjerg, Frede
2017-01-01
Detailed thermal dynamics of high power IGBT modules are important information for the reliability analysis and thermal design of power electronic systems. However, the existing thermal models have their limits to correctly predict these complicated thermal behavior in the IGBTs: The typically used...... thermal distribution under long-term studies. Meanwhile the boundary conditions for the thermal analysis are modeled and included, which can be adapted to different real field applications of power electronic converters. Finally, the accuracy of the proposed thermal model is verified by FEM simulations...... thermal model based on one-dimensional RC lumps have limits to provide temperature distributions inside the device, moreover some variable factors in the real-field applications like the cooling and heating conditions of the converter cannot be adapted. On the other hand, the more advanced three...
DEFF Research Database (Denmark)
Bahman, Amir Sajjad; Ma, Ke; Blaabjerg, Frede
2017-01-01
Detailed thermal dynamics of high power IGBT modules are important information for the reliability analysis and thermal design of power electronic systems. However, the existing thermal models have their limits to correctly predict these complicated thermal behavior in the IGBTs: The typically used...... thermal distribution under long-term studies. Meanwhile the boundary conditions for the thermal analysis are modeled and included, which can be adapted to different real-field applications of power electronic converters. Finally, the accuracy of the proposed thermal model is verified by FEM simulations...... thermal model based on one-dimensional RC lumps have limits to provide temperature distributions inside the device, moreover some variable factors in the real-field applications like the cooling and heating conditions of the converter cannot be adapted. On the other hand, the more advanced three...
An Introductory Idea for Teaching Two-Component Phase Diagrams
Peckham, Gavin D.; McNaught, Ian J.
2011-01-01
The teaching of two-component phase diagrams has attracted little attention in this "Journal," and it is hoped that this article will make a useful contribution. Current physical chemistry textbooks describe two-component phase diagrams adequately, but do so in a piecemeal fashion one section at a time; first solid-liquid equilibria, then…
Two-component micro injection moulding for hearing aid applications
DEFF Research Database (Denmark)
Islam, Aminul; Hansen, Hans Nørgaard; Marhöfer, David Maximilian
2012-01-01
Two-component (2k) injection moulding is an important process technique at the present state of technology, and it is growing rapidly in the field of precision micro moulding. Besides combining different material properties in the same product, two-component moulding can eliminate many assembly s...
Feedback Control of Two-Component Regulatory Systems.
Groisman, Eduardo A
2016-09-08
Two-component systems are a dominant form of bacterial signal transduction. The prototypical two-component system consists of a sensor that responds to a specific input(s) by modifying the output of a cognate regulator. Because the output of a two-component system is the amount of phosphorylated regulator, feedback mechanisms may alter the amount of regulator, and/or modify the ability of a sensor or other proteins to alter the phosphorylation state of the regulator. Two-component systems may display intrinsic feedback whereby the amount of phosphorylated regulator changes under constant inducing conditions and without the participation of additional proteins. Feedback control allows a two-component system to achieve particular steady-state levels, to reach a given steady state with distinct dynamics, to express coregulated genes in a given order, and to activate a regulator to different extents, depending on the signal acting on the sensor.
National Research Council Canada - National Science Library
Ishizuka, Masaru; Hatakeyama, Tomoyuki; Funawatashi, Yuichi; Koizumi, katsuhiro
2011-01-01
.... This paper describes an application of the thermal network method to the transient thermal analysis of multichip modules and proposes a simple model for the thermal analysis of multichip modules as a preliminary thermal design tool. On the basis of the result of transient thermal analysis, the validity of the thermal network method and the simple thermal analysis model is confirmed.
Electric mine motor thermal models aiding design and setting thermal protections
National Research Council Canada - National Science Library
R Krok
2012-01-01
Electric mine motor thermal models aiding design and setting thermal protections The paper presents original modified thermal networks for calculations of the temperature field in induction mine...
Validation of thermal models for a prototypical MEMS thermal actuator.
Energy Technology Data Exchange (ETDEWEB)
Gallis, Michail A.; Torczynski, John Robert; Piekos, Edward Stanley; Serrano, Justin Raymond; Gorby, Allen D.; Phinney, Leslie Mary
2008-09-01
This report documents technical work performed to complete the ASC Level 2 Milestone 2841: validation of thermal models for a prototypical MEMS thermal actuator. This effort requires completion of the following task: the comparison between calculated and measured temperature profiles of a heated stationary microbeam in air. Such heated microbeams are prototypical structures in virtually all electrically driven microscale thermal actuators. This task is divided into four major subtasks. (1) Perform validation experiments on prototypical heated stationary microbeams in which material properties such as thermal conductivity and electrical resistivity are measured if not known and temperature profiles along the beams are measured as a function of electrical power and gas pressure. (2) Develop a noncontinuum gas-phase heat-transfer model for typical MEMS situations including effects such as temperature discontinuities at gas-solid interfaces across which heat is flowing, and incorporate this model into the ASC FEM heat-conduction code Calore to enable it to simulate these effects with good accuracy. (3) Develop a noncontinuum solid-phase heat transfer model for typical MEMS situations including an effective thermal conductivity that depends on device geometry and grain size, and incorporate this model into the FEM heat-conduction code Calore to enable it to simulate these effects with good accuracy. (4) Perform combined gas-solid heat-transfer simulations using Calore with these models for the experimentally investigated devices, and compare simulation and experimental temperature profiles to assess model accuracy. These subtasks have been completed successfully, thereby completing the milestone task. Model and experimental temperature profiles are found to be in reasonable agreement for all cases examined. Modest systematic differences appear to be related to uncertainties in the geometric dimensions of the test structures and in the thermal conductivity of the
Implementation of Two Component Advective Flow Solution in XSPEC
Debnath, Dipak; Mondal, Santanu
2014-01-01
Spectral and Temporal properties of black hole candidates can be explained reasonably well using Chakrabarti-Titarchuk solution of two component advective flow (TCAF). This model requires two accretion rates, namely, the Keplerian disk accretion rate and the halo accretion rate, the latter being composed of a sub-Keplerian, low angular momentum flow which may or may not develop a shock. In this solution, the relevant parameter is the relative importance of the halo (which creates the Compton cloud region) rate with respect to the Keplerian disk rate (soft photon source). Though this model has been used earlier to manually fit data of several black hole candidates quite satisfactorily, for the first time, we made it user friendly by implementing it into XSPEC software of GSFC/NASA. This enables any user to extract physical parameters of the accretion flows, such as two accretion rates, the shock location, the shock strength etc. for any black hole candidate. We provide some examples of fitting a few cases usin...
Role of functionality in two-component signal transduction: A stochastic study
Maity, Alok Kumar; Bandyopadhyay, Arnab; Chaudhury, Pinaki; Banik, Suman K.
2014-03-01
We present a stochastic formalism for signal transduction processes in a bacterial two-component system. Using elementary mass action kinetics, the proposed model takes care of signal transduction in terms of a phosphotransfer mechanism between the cognate partners of a two-component system, viz., the sensor kinase and the response regulator. Based on the difference in functionality of the sensor kinase, the noisy phosphotransfer mechanism has been studied for monofunctional and bifunctional two-component systems using the formalism of the linear noise approximation. Steady-state analysis of both models quantifies different physically realizable quantities, e.g., the variance, the Fano factor (variance/mean), and mutual information. The resultant data reveal that both systems reliably transfer information of extracellular environment under low external stimulus and in a high-kinase-and-phosphatase regime. We extend our analysis further by studying the role of the two-component system in downstream gene regulation.
Receptor domains of two-component signal transduction systems.
Perry, Julie; Koteva, Kalinka; Wright, Gerard
2011-05-01
Two-component signal transduction systems are found ubiquitously in prokaryotes, and in archaea, fungi, yeast and some plants, where they regulate physiologic and molecular processes at both transcriptional and post-transcriptional levels. Two-component systems sense changes in environmental conditions when a specific ligand binds to the receptor domain of the histidine kinase sensory component. The structures of many histidine kinase receptors are known, including those which sense extracellular and cytoplasmic signals. In this review, we discuss the basic architecture of two-component signalling circuits, including known system ligands, structure and function of both receptor and signalling domains, the chemistry of phosphotransfer, and cross-talk between different two-component pathways. Given the importance of these systems in regulating cellular responses, many biochemical techniques have been developed for their study and analysis. We therefore also review current methods used to study two-component signalling, including a new affinity-based proteomics approach used to study inducible resistance to the antibiotic vancomycin through the VanSR two-component signal transduction system.
Asteroid thermal modeling: recent developments and applications
Harris, A. W.; Mueller, M.
2006-01-01
A variety of thermal models are used for the derivation of asteroid physical parameters from thermal-infrared observations Simple models based on spherical geometry are often adequate for obtaining sizes and albedos when very little information about an object is available However sophisticated ther
Asteroid thermal modeling: recent developments and applications
Harris, A. W.; Mueller, M.
2006-01-01
A variety of thermal models are used for the derivation of asteroid physical parameters from thermal-infrared observations Simple models based on spherical geometry are often adequate for obtaining sizes and albedos when very little information about an object is available However sophisticated
Two-component perfect fluid in FRW universe
,
2012-01-01
We propose the cosmological model which allows to describe on equal footing the evolution of matter in the universe on the time interval from the inflation till the domination of dark energy. The matter is considered as a two-component perfect fluid imitated by homogeneous scalar fields between which there is energy exchange. Dark energy is represented by the cosmological constant, which is supposed invariable during the whole evolution of the universe. The matter changes its equation of state with time, so that the era of radiation domination in the early universe smoothly passes into the era of a pressureless gas, which then passes into the late-time epoch, when the matter is represented by a gas of low-velocity cosmic strings. The inflationary phase is described as an analytic continuation of the energy density in the very early universe into the region of small negative values of the parameter which characterizes typical time of energy transfer from one matter component to another. The Hubble expansion ra...
Energy Technology Data Exchange (ETDEWEB)
Erena, J.; Arandes, J.M.; Bilbao, J.; Gayubo, A.G. [Universidad del Pais Vasco, Bilbao (Spain). Dept. de Ingeneria Quimica; De Lasa, H.I. [University of Western Ontario, London, ONT (Canada). Chemical Reactor Engineering Centre
2000-05-01
The present study describes the kinetics of syngas transformation into liquid hydrocarbons (boiling point in the gasoline range) using as catalyst a mixture of a metallic component, Cr{sub 2}O{sub 3}-ZnO, and of an acidic component, ZSM-5 zeolite. Experimental results were obtained in an isothermal fixed-bed integral reactor. The validity of several kinetic models, available for methanol synthesis, is analysed and modifications are proposed. These changes involve a rate equation with a CO{sub 2} concentration-dependent term. Catalyst deactivation is also evaluated and the effect of the operating conditions on coke deposition is established. Moreover, the rate of CO conversion and the change of catalytic activity with time-on-stream were described using a kinetic model showing a weak influence of temperature. (Author)
Conductive thermal modeling of Wyoming geothermal systems
Energy Technology Data Exchange (ETDEWEB)
Heasler, H.P.; Ruscetta, C.A.; Foley, D. (eds.)
1981-05-01
A summary of techniques used by the Wyoming Geothermal Resource Assessment Group in defining low-temperature hydrothermal resource areas is presented. Emphasis is placed on thermal modeling techniques appropriate to Wyoming's geologic setting. Thermal parameters discussed include oil-well bottom hole temperatures, heat flow, thermal conductivity, and measured temperature-depth profiles. Examples of the use of these techniques are from the regional study of the Bighorn Basin and two site specific studies within the Basin.
Two component systems: physiological effect of a third component.
Directory of Open Access Journals (Sweden)
Baldiri Salvado
Full Text Available Signal transduction systems mediate the response and adaptation of organisms to environmental changes. In prokaryotes, this signal transduction is often done through Two Component Systems (TCS. These TCS are phosphotransfer protein cascades, and in their prototypical form they are composed by a kinase that senses the environmental signals (SK and by a response regulator (RR that regulates the cellular response. This basic motif can be modified by the addition of a third protein that interacts either with the SK or the RR in a way that could change the dynamic response of the TCS module. In this work we aim at understanding the effect of such an additional protein (which we call "third component" on the functional properties of a prototypical TCS. To do so we build mathematical models of TCS with alternative designs for their interaction with that third component. These mathematical models are analyzed in order to identify the differences in dynamic behavior inherent to each design, with respect to functionally relevant properties such as sensitivity to changes in either the parameter values or the molecular concentrations, temporal responsiveness, possibility of multiple steady states, or stochastic fluctuations in the system. The differences are then correlated to the physiological requirements that impinge on the functioning of the TCS. This analysis sheds light on both, the dynamic behavior of synthetically designed TCS, and the conditions under which natural selection might favor each of the designs. We find that a third component that modulates SK activity increases the parameter space where a bistable response of the TCS module to signals is possible, if SK is monofunctional, but decreases it when the SK is bifunctional. The presence of a third component that modulates RR activity decreases the parameter space where a bistable response of the TCS module to signals is possible.
Transmutation Fuel Performance Code Thermal Model Verification
Energy Technology Data Exchange (ETDEWEB)
Gregory K. Miller; Pavel G. Medvedev
2007-09-01
FRAPCON fuel performance code is being modified to be able to model performance of the nuclear fuels of interest to the Global Nuclear Energy Partnership (GNEP). The present report documents the effort for verification of the FRAPCON thermal model. It was found that, with minor modifications, FRAPCON thermal model temperature calculation agrees with that of the commercial software ABAQUS (Version 6.4-4). This report outlines the methodology of the verification, code input, and calculation results.
Circulation Condition of Two-component Bose-Einstein Condensate
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
In the report we point out that there exists an intrinsic difference in the internal symmetry of the two components spin-1/2 Bose condensates from that of spinor Bose condensates of the atoms with hyperfine states of nonzero integer-spins,which gives rise to a new topological constrain on the circulation for this two-component spin-1/2 Bose condensates.It is shown that the SU(2) symmetry of the spin-1/2 Bose condensate implies a
Itinerant Ferromagnetism in a Polarized Two-Component Fermi Gas
DEFF Research Database (Denmark)
Massignan, Pietro; Yu, Zhenhua; Bruun, Georg
2013-01-01
We analyze when a repulsively interacting two-component Fermi gas becomes thermodynamically unstable against phase separation. We focus on the strongly polarized limit, where the free energy of the homogeneous mixture can be calculated accurately in terms of well-defined quasiparticles, the repul......We analyze when a repulsively interacting two-component Fermi gas becomes thermodynamically unstable against phase separation. We focus on the strongly polarized limit, where the free energy of the homogeneous mixture can be calculated accurately in terms of well-defined quasiparticles...
Two-component Fermi-liquid theory - Equilibrium properties of liquid metallic hydrogen
Oliva, J.; Ashcroft, N. W.
1981-01-01
It is reported that the transition of condensed hydrogen from an insulating molecular crystal phase to a metallic liquid phase, at zero temperature and high pressure, appears possible. Liquid metallic hydrogen (LMH), comprising interpenetrating proton and electron fluids, would constitute a two-component Fermi liquid with both a very high component-mass ratio and long-range, species-dependent bare interactions. The low-temperature equilibrium properties of LMH are examined by means of a generalization to the case of two components of the phenomenological Landau Fermi-liquid theory, and the low-temperature specific heat, compressibility, thermal expansion coefficient and spin susceptibility are given. It is found that the specific heat and the thermal expansion coefficient are vastly greater in the liquid than in the corresponding solid, due to the presence of proton quasiparticle excitations in the liquid.
Two-component Fermi-liquid theory - Equilibrium properties of liquid metallic hydrogen
Oliva, J.; Ashcroft, N. W.
1981-01-01
It is reported that the transition of condensed hydrogen from an insulating molecular crystal phase to a metallic liquid phase, at zero temperature and high pressure, appears possible. Liquid metallic hydrogen (LMH), comprising interpenetrating proton and electron fluids, would constitute a two-component Fermi liquid with both a very high component-mass ratio and long-range, species-dependent bare interactions. The low-temperature equilibrium properties of LMH are examined by means of a generalization to the case of two components of the phenomenological Landau Fermi-liquid theory, and the low-temperature specific heat, compressibility, thermal expansion coefficient and spin susceptibility are given. It is found that the specific heat and the thermal expansion coefficient are vastly greater in the liquid than in the corresponding solid, due to the presence of proton quasiparticle excitations in the liquid.
Two component permeation through thin zeolite MFI membranes
Keizer, K.; Burggraaf, A.J.; Vroon, Z.A.E.P.; Verweij, H.
1998-01-01
Two component permeation measurements have been performed by the Wicke-Kallenbach method on a thin (3 μm) zeolite MFI (Silicalite-1) membrane with molecules of different kinetic diameters, d(k). The membrane was supported by a flat porous α-Al2O3 substrate. The results obtained could be classified i
two component permeation through thin zeolite MFI membranes
Keizer, Klaas; Burggraaf, Anthonie; Burggraaf, A.J.; Vroon, Z.A.E.P.; Vroon, Z.A.E.P.; Verweij, H.
1998-01-01
Two component permeation measurements have been performed by the Wicke–Kallenbach method on a thin (3 μm) zeolite MFI (Silicalite-1) membrane with molecules of different kinetic diameters, dk. The membrane was supported by a flat porous -Al2O3 substrate. The results obtained could be classified in s
TWO-COMPONENT JETS AND THE FANAROFF-RILEY DICHOTOMY
Meliani, Z.; Keppens, R.; Sauty, C.
2010-01-01
Transversely stratified jets are observed in many classes of astrophysical objects, ranging from young stellar objects, mu-quasars, to active galactic nuclei and even in gamma-ray bursts. Theoretical arguments support this transverse stratification of jets with two components induced by intrinsic fe
Two component injection moulding: Present and future perspectives
DEFF Research Database (Denmark)
Islam, Aminul; Hansen, Hans Nørgaard
2009-01-01
Two component injection moulding has widespread industrial applications. Still the technology is yet to gain its full potential in highly demanding and technically challenging applications areas. The smart use of this technology can open the doors for cost effective and convergent manufacturing...
Entanglement Properties in Two-Component Bose-Einstein Condensate
Jiang, Di-You
2016-10-01
We investigate entanglement inseparability and bipartite entanglement of in two-component Bose-Einstein condensate in the presence of the nonlinear interatomic interaction, interspecies interaction. Entanglement inseparability and bipartite entanglement have the similar properties. More entanglement can be generated by adjusting the nonlinear interatomic interaction and control the time interval of the entanglement by adjusting interspecies interaction.
Kox, Linda F.F.; Wösten, Marc M. S. M.; Groisman, Eduardo A.
2000-01-01
The PmrA–PmrB two-component system of Salmonella enterica controls resistance to the peptide antibiotic polymyxin B and to several antimicrobial proteins from human neutrophils. Transcription of PmrA-activated genes is induced by high iron, but can also be promoted by growth in low magnesium in a process that requires another two-component system, PhoP–PhoQ. Here, we define the genetic basis for the interaction between the PhoP–PhoQ and PmrA–PmrB systems. We have identified pmrD as a PhoP-act...
Thermal modelling of friction stir welding
DEFF Research Database (Denmark)
Schmidt, Henrik Nikolaj Blicher; Hattel, Jesper Henri
2008-01-01
The objective of the present work is to present the basic elements of the thermal modelling of friction stir welding as well as to clarify some of the uncertainties in the literature regarding the different contributions to the heat generation. Some results from a new thermal pseudomechanical model...... in which the temperature-dependent yield stress of the weld material controls the heat generation are also presented....
The dynamics of nonstationary solutions in one-dimensional two-component Bose-Einstein condensates
Institute of Scientific and Technical Information of China (English)
Lü Bin-Bin; Hao Xue; Tian Qiang
2011-01-01
This paper investigates the dynamical properties of nonstationary solutions in one-dimensional two-component Bose-Einstein condensates. It gives three kinds of stationary solutions to this model and develops a general method of constructing nonstationary solutions. It obtains the unique features about general evolution and soliton evolution of nonstationary solutions in this model.
Modeling and Thermal Analysis of Disc
Directory of Open Access Journals (Sweden)
Brake Praveena S
2014-10-01
Full Text Available The disc brake is a device used for slowing or stopping the rotation of the vehicle. Number of times using the brake for vehicle leads to heat generation during braking event, such that disc brake undergoes breakage due to high Temperature. Disc brake model is done by CATIA and analysis is done by using ANSYS workbench. The main purpose of this project is to study the Thermal analysis of the Materials for the Aluminum, Grey Cast Iron, HSS M42, and HSS M2. A comparison between the four materials for the Thermal values and material properties obtained from the Thermal analysis low thermal gradient material is preferred. Hence best suitable design, low thermal gradient material Grey cast iron is preferred for the Disc Brakes for better performance.
YORP torques with 1D thermal model
Breiter, Slawomir; Czekaj, Maria
2010-01-01
A numerical model of the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect for objects defined in terms of a triangular mesh is described. The algorithm requires that each surface triangle can be handled independently, which implies the use of a 1D thermal model. Insolation of each triangle is determined by an optimized ray-triangle intersection search. Surface temperature is modeled with a spectral approach; imposing a quasi-periodic solution we replace heat conduction equation by the Helmholtz equation. Nonlinear boundary conditions are handled by an iterative, FFT based solver. The results resolve the question of the YORP effect in rotation rate independence on conductivity within the nonlinear 1D thermal model regardless of the accuracy issues and homogeneity assumptions. A seasonal YORP effect in attitude is revealed for objects moving on elliptic orbits when a nonlinear thermal model is used.
A two-component NZRI metamaterial based rectangular cloak
Islam, Sikder Sunbeam; Faruque, Mohammd Rashed Iqbal; Islam, Mohammad Tariqul
2015-10-01
A new two-component, near zero refractive index (NZRI) metamaterial is presented for electromagnetic rectangular cloaking operation in the microwave range. In the basic design a pi-shaped, metamaterial was developed and its characteristics were investigated for the two major axes (x and z-axis) wave propagation through the material. For the z-axis wave propagation, it shows more than 2 GHz bandwidth and for the x-axis wave propagation; it exhibits more than 1 GHz bandwidth of NZRI property. The metamaterial was then utilized in designing a rectangular cloak where a metal cylinder was cloaked perfectly in the C-band area of microwave regime. The experimental result was provided for the metamaterial and the cloak and these results were compared with the simulated results. This is a novel and promising design for its two-component NZRI characteristics and rectangular cloaking operation in the electromagnetic paradigm.
On a periodic two-component Hunter-Saxton equation
Kohlmann, Martin
2011-01-01
We determine the solution of the geodesic equation associated with a periodic two-component Hunter-Saxton system on a semidirect product obtained from the diffeomorphism group of the circle, modulo rigid rotations, and a space of scalar functions. In particular, we compute the time of breakdown of the geodesic flow. As a further goal, we establish a local well-posedness result for the two-component Hunter-Saxton system in the smooth category. The paper gets in line with some recent results for the generalized Hunter-Saxton equation provided by Escher, Wu and Wunsch in [J. Escher, Preprint 2010] and [H. Wu, M. Wunsch, arXiv:1009.1688v1 [math.AP
Two Component Injection Moulding for Moulded Interconnect Devices
DEFF Research Database (Denmark)
Islam, Aminul
The moulded interconnect devices (MIDs) contain huge possibilities for many applications in micro electro-mechanical-systems because of their potential in reducing the number of components, process steps and finally in miniaturization of the product. Among the available MID process chains, two...... component (2k) injection moulding is one of the most industrially adaptive processes. However, the use of two component injection moulding for MID fabrication, with circuit patterns in sub-millimeter range, is still a big challenge. This book searches for the technical difficulties associated...... with the process and makes attempts to overcome those challenges. In search of suitable polymer materials for MID applications, potential materials are characterized in terms of polymer-polymer bond strength, polymer-polymer interface quality and selective metallization. The experimental results find the factors...
Two-component microinjection moulding for MID fabrication
DEFF Research Database (Denmark)
Islam, Aminul; Hansen, Hans Nørgaard; Tang, Peter Torben
2010-01-01
Moulded interconnect devices (MIDs) are plastic substrates with electrical infrastructure. The fabrication of MIDs is usually based on injection moulding, and different process chains may be identified from this starting point. The use of MIDs has been driven primarily by the automotive sector......, but recently, the medical sector seems more and more interested. In particular, the possibility of miniaturisation of three-dimensional components with electrical infrastructure is attractive. The present paper describes possible manufacturing routes and challenges of miniaturised MIDs based on two......-component injection moulding and subsequent metallisation. This technology promises cost effective and convergent manufacturing approaches for both macro- and microapplications. This paper presents the results of industrial MID production based on two-component injection moulding and discusses the important issues...
The Fractional Virial Potential Energy in Two-Component Systems
Directory of Open Access Journals (Sweden)
Caimmi, R.
2008-12-01
Full Text Available Two-component systems are conceived as macrogases, and the related equation of state is expressed using the virial theorem for subsystems, under the restriction of homeoidally striated density profiles. Explicit calculations are performed for a useful reference case and a few cases of astrophysical interest, both with and without truncation radius. Shallower density profiles are found to yield an equation of state, $phi=phi(y,m$, characterized (for assigned values of the fractional mass, $m=M_j/ M_i$ by the occurrence of two extremum points, a minimum and a maximum, as found in an earlier attempt. Steeper density profiles produce a similar equation of state, which implies that a special value of $m$ is related to a critical curve where the above mentioned extremum points reduce to a single horizontal inflexion point, and curves below the critical one show no extremum points. The similarity of the isofractional mass curves to van der Waals' isothermal curves, suggests the possibility of a phase transition in a bell-shaped region of the $({sf O}yphi$ plane, where the fractional truncation radius along a selected direction is $y=R_j/R_i$, and the fractional virial potential energy is $phi=(E_{ji}_mathrm{vir}/(E_{ij}_mathrm{vir}$. Further investigation is devoted to mass distributions described by Hernquist (1990 density profiles, for which an additional relation can be used to represent a sample of $N=16$ elliptical galaxies (EGs on the $({sf O}yphi$ plane. Even if the evolution of elliptical galaxies and their hosting dark matter (DM haloes, in the light of the model, has been characterized by equal fractional mass, $m$, and equal scaled truncation radius, or concentration, $Xi_u=R_u/r_u^dagger$, $u=i,j$, still it cannot be considered as strictly homologous, due to different values of fractional truncation radii, $y$, or fractional scaling radii, $y^dagger=r_j^dagger/r_i^dagger$, deduced from sample objects.
Interaction Analysis of a Two-Component System Using Nanodiscs.
Directory of Open Access Journals (Sweden)
Patrick Hörnschemeyer
Full Text Available Two-component systems are the major means by which bacteria couple adaptation to environmental changes. All utilize a phosphorylation cascade from a histidine kinase to a response regulator, and some also employ an accessory protein. The system-wide signaling fidelity of two-component systems is based on preferential binding between the signaling proteins. However, information on the interaction kinetics between membrane embedded histidine kinase and its partner proteins is lacking. Here, we report the first analysis of the interactions between the full-length membrane-bound histidine kinase CpxA, which was reconstituted in nanodiscs, and its cognate response regulator CpxR and accessory protein CpxP. Using surface plasmon resonance spectroscopy in combination with interaction map analysis, the affinity of membrane-embedded CpxA for CpxR was quantified, and found to increase by tenfold in the presence of ATP, suggesting that a considerable portion of phosphorylated CpxR might be stably associated with CpxA in vivo. Using microscale thermophoresis, the affinity between CpxA in nanodiscs and CpxP was determined to be substantially lower than that between CpxA and CpxR. Taken together, the quantitative interaction data extend our understanding of the signal transduction mechanism used by two-component systems.
Rewiring the specificity of two-component signal transduction systems.
Skerker, Jeffrey M; Perchuk, Barrett S; Siryaporn, Albert; Lubin, Emma A; Ashenberg, Orr; Goulian, Mark; Laub, Michael T
2008-06-13
Two-component signal transduction systems are the predominant means by which bacteria sense and respond to environmental stimuli. Bacteria often employ tens or hundreds of these paralogous signaling systems, comprised of histidine kinases (HKs) and their cognate response regulators (RRs). Faithful transmission of information through these signaling pathways and avoidance of detrimental crosstalk demand exquisite specificity of HK-RR interactions. To identify the determinants of two-component signaling specificity, we examined patterns of amino acid coevolution in large, multiple sequence alignments of cognate kinase-regulator pairs. Guided by these results, we demonstrate that a subset of the coevolving residues is sufficient, when mutated, to completely switch the substrate specificity of the kinase EnvZ. Our results shed light on the basis of molecular discrimination in two-component signaling pathways, provide a general approach for the rational rewiring of these pathways, and suggest that analyses of coevolution may facilitate the reprogramming of other signaling systems and protein-protein interactions.
Thermal models pertaining to continental growth
Morgan, Paul; Ashwal, Lew
1988-01-01
Thermal models are important to understanding continental growth as the genesis, stabilization, and possible recycling of continental crust are closely related to the tectonic processes of the earth which are driven primarily by heat. The thermal energy budget of the earth was slowly decreasing since core formation, and thus the energy driving the terrestrial tectonic engine was decreasing. This fundamental observation was used to develop a logic tree defining the options for continental growth throughout earth history.
Modulational instability of two-component Bose-Einstein condensates in an optical lattice
Jin, G R; Nahm, K; Jin, Guang-Ri; Kim, Chul Koo; Nahm, Kyun
2004-01-01
We study modulational instability of two-component Bose-Einstein condensates in a deep optical lattice, which is modelled as a coupled discrete nonlinear Schr\\"{o}dinger equation. The excitation spectrum and the modulational instability condition of the total system are presented analytically. In the long-wavelength limit, our results agree with the homogeneous two-component Bose-Einstein condensates case. The discreteness effects result in the appearance of the modulational instability for the condensates in miscible region. The numerical calculations confirm our analytical results and show that the interspecies coupling can transfer the instability from one component to another.
Mapder, Tarunendu; Banik, Suman K
2016-01-01
Studies on the role of fluctuations in signal propagation and on gene regulation in monoclonal bacterial population have been extensively pursued based on the machinery of two-component system. The bacterial two-component system shows noise utilisation through its inherent plasticity. The fluctuations propagation takes place using the phosphotransfer module and the feedback mechanism during gene regulation. To delicately observe the noisy kinetics the generic cascade needs stochastic investigation at the mRNA and protein levels. To this end, we propose a theoretical framework to investigate the noisy signal transduction in a generic two-component system. The model shows reliability in information transmission through quantification of several statistical measures. We further extend our analysis to observe the protein distribution in a population of cells. Through numerical simulation, we identify the regime of the kinetic parameter set that generates a stability switch in the steady state distribution of prot...
Two-Component Signal Transduction Systems in the Cyanobacterium Synechocystis sp. PCC 6803
Institute of Scientific and Technical Information of China (English)
LIU Xingguo; HUANG Wei; WU Qingyu
2006-01-01
Two-component systems are signal transduction systems which enable bacteria to regulate cellular functions in response to changing environmental conditions. The unicellular Synechocystis sp. PCC 6803 has become a model organism for a range of biochemical and molecular biology studies aiming at investigating environmental stress response. The publication of the complete genome sequence of the cyanobacterium Synechocystis sp. PCC 6803 provided a tremendous stimulus for research in this field, and at least 80 open reading frames were identified as members of the two-component signal transduction systems in this single species of cyanobacteria. To date, functional roles have been determined for only a limited number of such proteins. This review summarizes our current knowledge about the two-component signal transduction systems in Synechocystis sp. PCC 6803 and describes recent achievements in elucidating the functional roles of these systems.
Impacts of photon bending on observational aspects of Two Component Advective Flow
Chatterjee, Arka
2016-01-01
Nature of photon trajectories in a curved spacetime around black holes are studied without constraining their motion to any plane. Impacts of photon bending are separately scrutinized for Keplerian and CENBOL components of Two Component Advective Flow (TCAF) model. Parameters like Red shift, Bolometric Flux, temperature profile and time of arrival of photons are also computed.
Thermal Conductivity Coefficient from Microscopic Models
Nemakhavhani, T E
2016-01-01
Thermal conductivity of hadron matter is studied using a microscopic transport model, which will be used to simulate ultra-relativistic heavy ion collisions at different energy densities, namely the Ultra-relativistic Quantum Molecular Dynamics (UrQMD). The molecular dynamics simulation is performed for a system of light mesons species (pion, rho, kaon) in a box with periodic boundary conditions. The equilibrium state is investigated by studying chemical equilibrium and thermal equilibrium of the system. Particle multiplicity equilibrates with time, and the energy spectra of different light mesons species have the same slopes and common temperatures when thermal equilibrium is reached. Thermal conductivity transport coefficient is calculated from the heat current - current correlations using the Green-Kubo relations.
Two-Component Multi-Parameter Time-Frequency Electromagnetics
Institute of Scientific and Technical Information of China (English)
HuangZhou; DongWeibin; HeTiezhi
2003-01-01
The two-component multi-parameter time-frequency electromagnetic method, used for the development of oilfields,makes use of both the traditional individual conductivity parameters of oil-producing layers and the dispersion information of the conductivity, i.e., the induced polarization parameter. The frequency-domain dispersion data is used to delineate the contacts between oil and water and the time domain dBz/dt component is used to estimate the depths to the un-known reservoirs so as to offer significant data in many aspects for oil exploration and detection.
Two component micro injection moulding for moulded interconnect devices
DEFF Research Database (Denmark)
Islam, Aminul
2008-01-01
Moulded interconnect devices (MIDs) contain huge possibilities for many applications in micro electro-mechanical-systems because of their capability of reducing the number of components, process steps and finally in miniaturization of the product. Among the available MID process chains, two...... and a reasonable adhesion between them. • Selective metallization of the two component plastic part (coating one polymer with metal and leaving the other one uncoated) To overcome these two main issues in MID fabrication for micro applications, the current Ph.D. project explores the technical difficulties...
Two-component Fermi gas in a Harmonic Trap
Yi, X X; Cui, H T; Zhang, C M
2002-01-01
We consider a mixture of two-component Fermi gases at low temperature. The density profile of this degenerate Fermi gas is calculated under the semiclassical approximation. The results show that the fermion-fermion interactions make a large correction to the density profile at low temperature. The phase separation of such a mixture is also discussed for both attractive and repulsive interatomic interactions, and the numerical calculations demonstrate the exist of a stable temperature region $T_{c1}
Interaction potentials and thermodynamic properties of two component semiclassical plasma
Energy Technology Data Exchange (ETDEWEB)
Ramazanov, T. S.; Moldabekov, Zh. A.; Ismagambetova, T. N. [Al-Farabi Kazakh National University, IETP, 71 al-Farabi Av., Almaty 050040 (Kazakhstan); Gabdullin, M. T. [Al-Farabi Kazakh National University, NNLOT, 71 al-Farabi Av., Almaty 050040 (Kazakhstan)
2014-01-15
In this paper, the effective interaction potential in two component semiclassical plasma, taking into account the long-range screening and the quantum-mechanical diffraction effects at short distances, is obtained on the basis of dielectric response function method. The structural properties of the semiclassical plasma are considered. The thermodynamic characteristics (the internal energy and the equation of state) are calculated using two methods: the method of effective potentials and the method of micropotentials with screening effect taken into account by the Ornstein-Zernike equation in the HNC approximation.
Itinerant ferromagnetism in a polarized two-component Fermi gas.
Massignan, Pietro; Yu, Zhenhua; Bruun, Georg M
2013-06-07
We analyze when a repulsively interacting two-component Fermi gas becomes thermodynamically unstable against phase separation. We focus on the strongly polarized limit, where the free energy of the homogeneous mixture can be calculated accurately in terms of well-defined quasiparticles, the repulsive polarons. Phase diagrams as a function of polarization, temperature, mass imbalance, and repulsive polaron energy, as well as scattering length and range parameter, are provided. We show that the lifetime of the repulsive polaron increases significantly with the interaction range and the mass of the minority atoms, raising the prospects of detecting the transition to the elusive itinerant ferromagnetic state with ultracold atoms.
Two component micro injection molding for MID fabrication
DEFF Research Database (Denmark)
Islam, Mohammad Aminul; Hansen, Hans Nørgaard; Tang, Peter Torben
2009-01-01
Molded Interconnect Devices (MIDs) are plastic substrates with electrical infrastructure. The fabrication of MIDs is usually based on injection molding and different process chains may be identified from this starting point. The use of MIDs has been driven primarily by the automotive sector......, but recently the medical sector seems more and more interested. In particular the possibility of miniaturization of 3D components with electrical infrastructure is attractive. The paper describes possible manufacturing routes and challenges of miniaturized MIDs based on two component micro injection molding...
Origin and evolution of two-component debris discs and an application to the q$^1$ Eridani system
Schüppler, Christian; Löhne, Torsten; Booth, Mark; Kirchschlager, Florian; Wolf, Sebastian
2016-01-01
Many debris discs reveal a two-component structure, with an outer Kuiper-belt analogue and a warm inner component whose origin is still a matter of debate. One possibility is that warm emission stems from an "asteroid belt" closer in to the star. We consider a scenario in which a set of giant planets is formed in an initially extended planetesimal disc. These planets carve a broad gap around their orbits, splitting up the disc into the outer and the inner belts. After the gas dispersal, both belts undergo collisional evolution in a steady-state regime. This scenario is explored with detailed collisional simulations involving realistic physics to describe a long-term collisional depletion of the two-component disc. We find that the inner disc may be able to retain larger amounts of material at older ages than thought before on the basis of simplified analytic models. We show that the proposed scenario is consistent with a suite of thermal emission and scattered light observational data for a bright two-tempera...
Turbulence modelling of thermal plasma flows
Shigeta, Masaya
2016-12-01
This article presents a discussion of the ideas for modelling turbulent thermal plasma flows, reviewing the challenges, efforts, and state-of-the-art simulations. Demonstrative simulations are also performed to present the importance of numerical methods as well as physical models to express turbulent features. A large eddy simulation has been applied to turbulent thermal plasma flows to treat time-dependent and 3D motions of multi-scale eddies. Sub-grid scale models to be used should be able to express not only turbulent but also laminar states because both states co-exist in and around thermal plasmas which have large variations of density as well as transport properties under low Mach-number conditions. Suitable solution algorithms and differencing schemes must be chosen and combined appropriately to capture multi-scale eddies and steep gradients of temperature and chemical species, which are turbulent features of thermal plasma flows with locally variable Reynolds and Mach numbers. Several simulations using different methods under different conditions show commonly that high-temperature plasma regions exhibit less turbulent structures, with only large eddies, whereas low-temperature regions tend to be more turbulent, with numerous small eddies. These numerical results agree with both theoretical insight and photographs that show the characteristics of eddies. Results also show that a turbulence transition of a thermal plasma jet through a generation-breakup process of eddies in a torch is dominated by fluid dynamic instability after ejection rather than non-uniform or unsteady phenomena.
Evolution of two-component signal transduction systems.
Capra, Emily J; Laub, Michael T
2012-01-01
To exist in a wide range of environmental niches, bacteria must sense and respond to a variety of external signals. A primary means by which this occurs is through two-component signal transduction pathways, typically composed of a sensor histidine kinase that receives the input stimuli and then phosphorylates a response regulator that effects an appropriate change in cellular physiology. Histidine kinases and response regulators have an intrinsic modularity that separates signal input, phosphotransfer, and output response; this modularity has allowed bacteria to dramatically expand and diversify their signaling capabilities. Recent work has begun to reveal the molecular basis by which two-component proteins evolve. How and why do orthologous signaling proteins diverge? How do cells gain new pathways and recognize new signals? What changes are needed to insulate a new pathway from existing pathways? What constraints are there on gene duplication and lateral gene transfer? Here, we review progress made in answering these questions, highlighting how the integration of genome sequence data with experimental studies is providing major new insights.
The Evolution of Two-Component Signal Transduction Systems
Capra, Emily J.; Laub, Michael T.
2014-01-01
To exist in a wide range of environmental niches, bacteria must sense and respond to a myriad of external signals. A primary means by which this occurs is through two-component signal transduction pathways, typically comprised of a histidine kinase that receives the input stimuli and a response regulator that effects an appropriate change in cellular physiology. Histidine kinases and response regulators have an intrinsic modularity that separates signal input, phosphotransfer, and output response; this modularity has allowed bacteria to dramatically expand and diversify their signaling capabilities. Recent work has begun to reveal the molecular basis by which two-component proteins evolve. How and why do orthologous signaling proteins diverge? How do cells gain new pathways and recognize new signals? What changes are needed to insulate a new pathway from existing pathways? What constraints are there on gene duplication and lateral gene transfer? Here, we review progress made in answering these questions, highlighting how the integration of genome sequence data with experimental studies is providing major new insights. PMID:22746333
Homogenized thermal conduction model for particulate foods
Energy Technology Data Exchange (ETDEWEB)
Chinesta, Francisco [Laboratoire de mecanique des systemes et des procedes, Ecole nationale superieure d' arts et metiers, 151 boulevard de l' Hopital, 75013, Paris (France); Torres, Rafael [Departamento de Ingenieria Mecanica, Universidad Politecnica de Valencia, Camino de Vera s/n. 46071, Valencia (Spain); Ramon, Antonio [AIMPLAS, Gustave Eiffel 4, 46980 Paterna, Valencia (Spain); Rodrigo, Mari Carmen; Rodrigo, Miguel [Instituto de Agroquimica y Tecnologia de Alimentos, Consejo Superior de Investigaciones Cientificas, Apartado de correos 73, 46100, Burjasot (Spain)
2002-12-01
This paper deals with the definition of an equivalent thermal conductivity for particulate foods. An homogenized thermal model is used to asses the effect of particulate spatial distribution and differences in thermal conductivities. We prove that the spatial average of the conductivity can be used in an homogenized heat transfer model if the conductivity differences among the food components are not very large, usually the highest conductivity ratio between the foods components is lower than 5. In the general case we propose to use a standard spatial homogenization procedure. Although the heterogeneity give rise to an anisotropic heat transfer behaviour, this effect is negligible when the food particles are randomly distributed. When we use pre-mixed particulate foods a statistical average can be defined from a small number of possible particle arrangements. (authors)
Modeling thermal protection outfits for fire exposures
Song, Guowen
2002-01-01
A numerical model has been developed that successfully predicts heat transfer through thermally protective clothing materials and garments exposed to intense heat. The model considers the effect of fire exposure to the thermophysical properties of materials as well as the air layers between the clothing material and skin surface. These experiments involved characterizing the flash fire surrounding the manikin by measuring the temperature of the flame above each thermal sensor in the manikin surface. An estimation method is used to calculate the heat transfer coefficient for each thermal sensor in a 4 second exposure to an average heat flux of 2.00cal/cm2sec. A parameter estimation method was used to estimate heat induced change in fabric thermophysical properties. The skin-clothe air gap distribution of different garments was determined using three-dimensional body scanning technology. Multi-layer skin model and a burn prediction method were used to predict second and third degree burns. The integrated generalized model developed was validated using the "Pyroman" Thermal Protective Clothing Analysis System with Kevlar/PBIRTM and NomexRTMIIIA coverall garments with different configuration and exposure time. A parametric study conducted using this numerical model indicated the influencing parameters on garment thermal protective performance in terms of skin burn damage subjected to 4 second flash fire exposure. The importance of these parameters is analyzed and distinguished. These parameters includes fabric thermophysical properties, PyromanRTM chamber flash fire characteristics, garment shrinkage and fit factors, as well as garment initial and test ambient temperature. Different skin models and their influence on burn prediction were also investigated using this model.
A General Thermal Equilibrium Discharge Flow Model
Institute of Scientific and Technical Information of China (English)
ZHAO; Min-fu; ZHANG; Dong-xu; LV; Yu-feng
2015-01-01
In isentropic and thermal equilibrium assumptions,a discharge flow model was derived,which unified the rules of normal temperature water discharge,high temperature and high pressure water discharge,two-phase critical flow,saturated steam and superheated steam critical
Thermal, chemical, and mechanical cookoff modeling
Energy Technology Data Exchange (ETDEWEB)
Hobbs, M.L.; Baer, M.R.; Gross, R.J.
1994-08-01
A Thermally Reactive, Elastic-plastic eXplosive code, TREX, has been developed to analyze coupled thermal, chemical and mechanical effects associated with cookoff simulation of confined or unconfined energetic materials. In confined systems, pressure buildup precedes thermal runaway, and unconfined energetic material expands to relieve high stress. The model was developed based on nucleation, decomposition chemistry, and elastic/plastic mechanical behavior of a material with a distribution of internal defects represented as clusters of spherical inclusions. A local force balance, with mass continuity constraints, forms the basis of the model requiring input of temperature and reacted gas fraction. This constitutive material model has been incorporated into a quasistatic mechanics code SANTOS as a material module which predicts stress history associated with a given strain history. The thermal-chemical solver XCHEM has been coupled to SANTOS to provide temperature and reacted gas fraction. Predicted spatial history variables include temperature, chemical species, solid/gas pressure, solid/gas density, local yield stress, and gas volume fraction. One-Dimensional Time to explosion (ODTX) experiments for TATB and PBX 9404 (HMX and NC) are simulated using global multistep kinetic mechanisms and the reactive elastic-plastic constitutive model. Pressure explosions, rather than thermal runaway, result in modeling slow cookoff experiments of confined conventional energetic materials such as TATB. For PBX 9404, pressure explosions also occur at fast cookoff conditions because of low temperature reactions of nitrocellulose resulting in substantial pressurization. A demonstrative calculation is also presented for reactive heat flow in a hollow, propellant-filled, stainless steel cylinder, representing a rocket motor. This example simulation show
Two-component systems and toxinogenesis regulation in Clostridium botulinum.
Connan, Chloé; Popoff, Michel R
2015-05-01
Botulinum neurotoxins (BoNTs) are the most potent toxins ever known. They are mostly produced by Clostridium botulinum but also by other clostridia. BoNTs associate with non-toxic proteins (ANTPs) to form complexes of various sizes. Toxin production is highly regulated through complex networks of regulatory systems involving an alternative sigma factor, BotR, and at least 6 recently described two-component systems (TCSs). TCSs allow bacteria to sense environmental changes and to respond to various stimuli by regulating the expression of specific genes at a transcriptional level. Several environmental stimuli have been identified to positively or negatively regulate toxin synthesis; however, the link between environmental stimuli and TCSs is still elusive. This review aims to highlight the role of TCSs as a central point in the regulation of toxin production in C. botulinum.
Exact two-component relativistic energy band theory and application
Energy Technology Data Exchange (ETDEWEB)
Zhao, Rundong; Zhang, Yong; Xiao, Yunlong; Liu, Wenjian, E-mail: liuwj@pku.edu.cn [Beijing National Laboratory for Molecular Sciences, Institute of Theoretical and Computational Chemistry, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, and Center for Computational Science and Engineering, Peking University, Beijing 100871 (China)
2016-01-28
An exact two-component (X2C) relativistic density functional theory in terms of atom-centered basis functions is proposed for relativistic calculations of band structures and structural properties of periodic systems containing heavy elements. Due to finite radial extensions of the local basis functions, the periodic calculation is very much the same as a molecular calculation, except only for an Ewald summation for the Coulomb potential of fluctuating periodic monopoles. For comparison, the nonrelativistic and spin-free X2C counterparts are also implemented in parallel. As a first and pilot application, the band gaps, lattice constants, cohesive energies, and bulk moduli of AgX (X = Cl, Br, I) are calculated to compare with other theoretical results.
Dynamics of two-component membranes surrounded by viscoelastic media.
Komura, Shigeyuki; Yasuda, Kento; Okamoto, Ryuichi
2015-11-01
We discuss the dynamics of two-component fluid membranes which are surrounded by viscoelastic media. We assume that membrane-embedded proteins can diffuse laterally and induce a local membrane curvature. The mean squared displacement of a tagged membrane segment is obtained as a generalized Einstein relation. When the elasticity of the surrounding media obeys a power-law behavior in frequency, an anomalous diffusion of the membrane segment is predicted. We also consider the situation where the proteins generate active non-equilibrium forces. The generalized Einstein relation is further modified by an effective temperature that depends on the force dipole energy. The obtained generalized Einstein relations are useful for membrane microrheology experiments.
Exact two-component relativistic energy band theory and application.
Zhao, Rundong; Zhang, Yong; Xiao, Yunlong; Liu, Wenjian
2016-01-28
An exact two-component (X2C) relativistic density functional theory in terms of atom-centered basis functions is proposed for relativistic calculations of band structures and structural properties of periodic systems containing heavy elements. Due to finite radial extensions of the local basis functions, the periodic calculation is very much the same as a molecular calculation, except only for an Ewald summation for the Coulomb potential of fluctuating periodic monopoles. For comparison, the nonrelativistic and spin-free X2C counterparts are also implemented in parallel. As a first and pilot application, the band gaps, lattice constants, cohesive energies, and bulk moduli of AgX (X = Cl, Br, I) are calculated to compare with other theoretical results.
Recent advances in description of few two-component fermions
Kartavtsev, O I
2012-01-01
Overview of the recent advances in description of the few two-component fermions is presented. The zero-range interaction limit is generally considered to discuss the principal aspects of the few-body dynamics. Significant attention is paid to detailed description of two identical fermions of mass $m$ and a distinct particle of mass $m_1$; two universal $L^P = 1^-$ bound states arise for mass ratio $m/m_1$ increasing up to the critical value $\\mu_c \\approx 13.607$, beyond which the Efimov effect takes place. The topics considered include rigorous treatment of the few-fermion problem in the zero-range interaction limit, low-dimensional results, the four-body energy spectrum, crossover of the energy spectra for $m/m_1$ near the critical value $\\mu_c $, and properties of potential-dependent states. At last, enlisted are the problems, whose solution is in due course.
Molecular Mechanisms of Two-Component Signal Transduction.
Zschiedrich, Christopher P; Keidel, Victoria; Szurmant, Hendrik
2016-09-25
Two-component systems (TCS) comprising sensor histidine kinases and response regulator proteins are among the most important players in bacterial and archaeal signal transduction and also occur in reduced numbers in some eukaryotic organisms. Given their importance to cellular survival, virulence, and cellular development, these systems are among the most scrutinized bacterial proteins. In the recent years, a flurry of bioinformatics, genetic, biochemical, and structural studies have provided detailed insights into many molecular mechanisms that underlie the detection of signals and the generation of the appropriate response by TCS. Importantly, it has become clear that there is significant diversity in the mechanisms employed by individual systems. This review discusses the current knowledge on common themes and divergences from the paradigm of TCS signaling. An emphasis is on the information gained by a flurry of recent structural and bioinformatics studies.
Bond strength of two component injection moulded MID
DEFF Research Database (Denmark)
Islam, Mohammad Aminul; Hansen, Hans Nørgaard; Tang, Peter Torben
2006-01-01
Most products of the future will require industrially adapted, cost effective production processes and on this issue two-component (2K) injection moulding is a potential candidate for MID manufacturing. MID based on 2k injection moulded plastic part with selectively metallised circuit tracks allows...... the integration of electrical and mechanical functionalities in a real 3D structure. If 2k injection moulding is applied with two polymers, of which one is plateable and the other is not, it will be possible to make 3D electrical structures directly on the component. To be applicable in the real engineering field...... the two different plastic materials in the MID structure require good bonding between them. This paper finds suitable combinations of materials for MIDs from both bond strength and metallisation view-point. Plastic parts were made by two-shot injection moulding and the effects of some important process...
Determinants of specificity in two-component signal transduction.
Podgornaia, Anna I; Laub, Michael T
2013-04-01
Maintaining the faithful flow of information through signal transduction pathways is critical to the survival and proliferation of organisms. This problem is particularly challenging as many signaling proteins are part of large, paralogous families that are highly similar at the sequence and structural levels, increasing the risk of unwanted cross-talk. To detect environmental signals and process information, bacteria rely heavily on two-component signaling systems comprised of sensor histidine kinases and their cognate response regulators. Although most species encode dozens of these signaling pathways, there is relatively little cross-talk, indicating that individual pathways are well insulated and highly specific. Here, we review the molecular mechanisms that enforce this specificity. Further, we highlight recent studies that have revealed how these mechanisms evolve to accommodate the introduction of new pathways by gene duplication. Copyright © 2013 Elsevier Ltd. All rights reserved.
Rewiring two-component signal transduction with small RNAs.
Göpel, Yvonne; Görke, Boris
2012-04-01
Bacterial two-component systems (TCSs) and small regulatory RNAs (sRNAs) form densely interconnected networks that integrate and transduce information from the environment into fine-tuned changes of gene expression. Many TCSs control target genes indirectly through regulation of sRNAs, which in turn regulate gene expression by base-pairing with mRNAs or targeting a protein. Conversely, sRNAs may control TCS synthesis, thereby recruiting the TCS regulon to other regulatory networks. Several TCSs control expression of multiple homologous sRNAs providing the regulatory networks with further flexibility. These sRNAs act redundantly, additively or hierarchically on targets. The regulatory speed of sRNAs and their unique features in gene regulation make them ideal players extending the flexibility, dynamic range or timing of TCS signaling. Copyright © 2011 Elsevier Ltd. All rights reserved.
Auxiliary phosphatases in two-component signal transduction.
Silversmith, Ruth E
2010-04-01
Signal termination in two-component systems occurs by loss of the phosphoryl group from the response regulator protein. This review explores our current understanding of the structures, catalytic mechanisms and means of regulation of the known families of phosphatases that catalyze response regulator dephosphorylation. The CheZ and CheC/CheX/FliY families, despite different overall structures, employ identical catalytic strategies using an amide side chain to orient a water molecule for in-line attack of the aspartyl phosphate. Spo0E phosphatases contain sequence and structural features that suggest a strategy similar to the chemotaxis phosphatases but the mechanism used by the Rap phosphatases is not yet elucidated. Identification of features shared by phosphatase families may aid in the identification of currently unrecognized classes of response regulator phosphatases. Copyright 2010 Elsevier Ltd. All rights reserved.
How insects overcome two-component plant chemical defence
DEFF Research Database (Denmark)
Pentzold, Stefan; Zagrobelny, Mika; Rook, Frederik;
2014-01-01
Insect herbivory is often restricted by glucosylated plant chemical defence compounds that are activated by plant β-glucosidases to release toxic aglucones upon plant tissue damage. Such two-component plant defences are widespread in the plant kingdom and examples of these classes of compounds...... are alkaloid, benzoxazinoid, cyanogenic and iridoid glucosides as well as glucosinolates and salicinoids. Conversely, many insects have evolved a diversity of counteradaptations to overcome this type of constitutive chemical defence. Here we discuss that such counter-adaptations occur at different time points......-component chemical defence. These adaptations include host plant choice, non-disruptive feeding guilds and various physiological adaptations as well as metabolic enzymatic strategies of the insect’s digestive system. Furthermore, insect adaptations often act in combination, may exist in both generalists...
Parallel TREE code for two-component ultracold plasma analysis
Jeon, Byoungseon; Kress, Joel D.; Collins, Lee A.; Grønbech-Jensen, Niels
2008-02-01
The TREE method has been widely used for long-range interaction N-body problems. We have developed a parallel TREE code for two-component classical plasmas with open boundary conditions and highly non-uniform charge distributions. The program efficiently handles millions of particles evolved over long relaxation times requiring millions of time steps. Appropriate domain decomposition and dynamic data management were employed, and large-scale parallel processing was achieved using an intermediate level of granularity of domain decomposition and ghost TREE communication. Even though the computational load is not fully distributed in fine grains, high parallel efficiency was achieved for ultracold plasma systems of charged particles. As an application, we performed simulations of an ultracold neutral plasma with a half million particles and a half million time steps. For the long temporal trajectories of relaxation between heavy ions and light electrons, large configurations of ultracold plasmas can now be investigated, which was not possible in past studies.
Model calculation of thermal conductivity in antiferromagnets
Energy Technology Data Exchange (ETDEWEB)
Mikhail, I.F.I., E-mail: ifi_mikhail@hotmail.com; Ismail, I.M.M.; Ameen, M.
2015-11-01
A theoretical study is given of thermal conductivity in antiferromagnetic materials. The study has the advantage that the three-phonon interactions as well as the magnon phonon interactions have been represented by model operators that preserve the important properties of the exact collision operators. A new expression for thermal conductivity has been derived that involves the same terms obtained in our previous work in addition to two new terms. These two terms represent the conservation and quasi-conservation of wavevector that occur in the three-phonon Normal and Umklapp processes respectively. They gave appreciable contributions to the thermal conductivity and have led to an excellent quantitative agreement with the experimental measurements of the antiferromagnet FeCl{sub 2}. - Highlights: • The Boltzmann equations of phonons and magnons in antiferromagnets have been studied. • Model operators have been used to represent the magnon–phonon and three-phonon interactions. • The models possess the same important properties as the exact operators. • A new expression for the thermal conductivity has been derived. • The results showed a good quantitative agreement with the experimental data of FeCl{sub 2}.
Residual Stresses Modeled in Thermal Barrier Coatings
Freborg, A. M.; Ferguson, B. L.; Petrus, G. J.; Brindley, W. J.
1998-01-01
Thermal barrier coating (TBC) applications continue to increase as the need for greater engine efficiency in aircraft and land-based gas turbines increases. However, durability and reliability issues limit the benefits that can be derived from TBC's. A thorough understanding of the mechanisms that cause TBC failure is a key to increasing, as well as predicting, TBC durability. Oxidation of the bond coat has been repeatedly identified as one of the major factors affecting the durability of the ceramic top coat during service. However, the mechanisms by which oxidation facilitates TBC failure are poorly understood and require further characterization. In addition, researchers have suspected that other bond coat and top coat factors might influence TBC thermal fatigue life, both separately and through interactions with the mechanism of oxidation. These other factors include the bond coat coefficient of thermal expansion, the bond coat roughness, and the creep behavior of both the ceramic and bond coat layers. Although it is difficult to design an experiment to examine these factors unambiguously, it is possible to design a computer modeling "experiment" to examine the action and interaction of these factors, as well as to determine failure drivers for TBC's. Previous computer models have examined some of these factors separately to determine their effect on coating residual stresses, but none have examined all the factors concurrently. The purpose of this research, which was performed at DCT, Inc., in contract with the NASA Lewis Research Center, was to develop an inclusive finite element model to characterize the effects of oxidation on the residual stresses within the TBC system during thermal cycling as well as to examine the interaction of oxidation with the other factors affecting TBC life. The plasma sprayed, two-layer thermal barrier coating that was modeled incorporated a superalloy substrate, a NiCrAlY bond coat, and a ZrO2-8 wt % Y2O3 ceramic top coat. We
Thermal chain model of electro- and magnetorheology
Energy Technology Data Exchange (ETDEWEB)
MARTIN,JAMES E.
2000-04-06
Steady shear 3-D simulations of electro- and magnetorheology in a uniaxial field are presented. These large scale simulations are three dimensional, and include the effect of Brownian motion. In the absence of thermal fluctuations, the expected shear thinning viscosity is observed in steady shear, and a striped phase is seen to rapidly form in a uniaxial field, with a shear slip zone in each sheet. However, as the influence of Brownian motion increases, the fluid stress decreases, especially at lower Mason numbers, and the striped phase eventually disappears, even when the fluid stress is still high. To account for the uniaxial steady shear data the author proposes a microscopic chain model of the role played by thermal fluctuations on the rheology of ER and MR fluids that delineates the regimes where an applied field can impact the fluid viscosity, and gives an analytical prediction for the thermal effect.
Multiscale Modeling of UHTC: Thermal Conductivity
Lawson, John W.; Murry, Daw; Squire, Thomas; Bauschlicher, Charles W.
2012-01-01
We are developing a multiscale framework in computational modeling for the ultra high temperature ceramics (UHTC) ZrB2 and HfB2. These materials are characterized by high melting point, good strength, and reasonable oxidation resistance. They are candidate materials for a number of applications in extreme environments including sharp leading edges of hypersonic aircraft. In particular, we used a combination of ab initio methods, atomistic simulations and continuum computations to obtain insights into fundamental properties of these materials. Ab initio methods were used to compute basic structural, mechanical and thermal properties. From these results, a database was constructed to fit a Tersoff style interatomic potential suitable for atomistic simulations. These potentials were used to evaluate the lattice thermal conductivity of single crystals and the thermal resistance of simple grain boundaries. Finite element method (FEM) computations using atomistic results as inputs were performed with meshes constructed on SEM images thereby modeling the realistic microstructure. These continuum computations showed the reduction in thermal conductivity due to the grain boundary network.
Light-induced thermodiffusion in two-component media
Ivanov, V.; Ivanova, G.; Okishev, K.; Khe, V.
2017-01-01
We have theoretically studied the optical transmittance response of thin cell with liquid containing absorbing nanoparticles in a Gaussian beam field. The transmittance spatial changing is caused by thermal diffusion phenomenon (Soret effect) which produces the variations of concentration of absorbing nanoparticles. The thickness of optical cell (including windows) is significantly less than the size of the beam. As a result, an exact analytical expression for the one dimensional thermal task is derived, taking into account the Soret feedback that leads to the temperature rising on the axis of a Gaussian beam. We have experimentally studied this phenomenon in carbon nanosuspension.
Thermal modelling of Advanced LIGO test masses
Wang, Haoyu; Blair, Carl; Álvarez, Miguel Dovale; Brooks, Aidan; Kasprzack, Marie F.; Ramette, Joshua; Meyers, Patrick M.; Kaufer, Steffen; O'Reilly, Brian; Mow-Lowry, Conor M.; Freise, Andreas
2016-01-01
High-reflectivity fused silica mirrors are at the epicentre of today's advanced gravitational wave detectors. In these detectors, the mirrors interact with high power laser beams. As a result of finite absorption in the high reflectivity coatings the mirrors suffer from a variety of thermal effects that impact on the detectors' performance. We propose a model of the Advanced LIGO mirrors that introduces an empirical term to account for the radiative heat transfer between the mirror and its su...
Computational modeling of nuclear thermal rockets
Peery, Steven D.
1993-01-01
The topics are presented in viewgraph form and include the following: rocket engine transient simulation (ROCETS) system; ROCETS performance simulations composed of integrated component models; ROCETS system architecture significant features; ROCETS engineering nuclear thermal rocket (NTR) modules; ROCETS system easily adapts Fortran engineering modules; ROCETS NTR reactor module; ROCETS NTR turbomachinery module; detailed reactor analysis; predicted reactor power profiles; turbine bypass impact on system; and ROCETS NTR engine simulation summary.
Dynamical principles of two-component genetic oscillators.
Directory of Open Access Journals (Sweden)
Raúl Guantes
2006-03-01
Full Text Available Genetic oscillators based on the interaction of a small set of molecular components have been shown to be involved in the regulation of the cell cycle, the circadian rhythms, or the response of several signaling pathways. Uncovering the functional properties of such oscillators then becomes important for the understanding of these cellular processes and for the characterization of fundamental properties of more complex clocks. Here, we show how the dynamics of a minimal two-component oscillator is drastically affected by its genetic implementation. We consider a repressor and activator element combined in a simple logical motif. While activation is always exerted at the transcriptional level, repression is alternatively operating at the transcriptional (Design I or post-translational (Design II level. These designs display differences on basic oscillatory features and on their behavior with respect to molecular noise or entrainment by periodic signals. In particular, Design I induces oscillations with large activator amplitudes and arbitrarily small frequencies, and acts as an "integrator" of external stimuli, while Design II shows emergence of oscillations with finite, and less variable, frequencies and smaller amplitudes, and detects better frequency-encoded signals ("resonator". Similar types of stimulus response are observed in neurons, and thus this work enables us to connect very different biological contexts. These dynamical principles are relevant for the characterization of the physiological roles of simple oscillator motifs, the understanding of core machineries of complex clocks, and the bio-engineering of synthetic oscillatory circuits.
Kim, Jeong-Rae; Cho, Kwang-Hyun
2006-12-01
E. coli has two-component systems composed of histidine kinase proteins and response regulator proteins. For a given extracellular stimulus, a histidine kinase senses the stimulus, autophosphorylates and then passes the phosphates to the cognate response regulators. The histidine kinase in an orthodox two-component system has only one histidine domain where the autophosphorylation occurs, but a histidine kinase in some unusual two-component systems (unorthodox two-component systems) has two histidine domains and one aspartate domain. So, the unorthodox two-component systems have more complex phosphorelay mechanisms than orthodox two-component systems. In general, the two-component systems are required to promptly respond to external stimuli for survival of E. coli. In this respect, the complex multi-step phosphorelay mechanism seems to be disadvantageous, but there are several unorthodox two-component systems in E. coli. In this paper, we investigate the reason why such unorthodox two-component systems are present in E. coli. For this purpose, we have developed simplified mathematical models of both orthodox and unorthodox two-component systems and analyzed their dynamical characteristics through extensive computer simulations. We have finally revealed that the unorthodox two-component systems realize ultrasensitive responses to external stimuli and also more robust responses to noises than the orthodox two-component systems.
Histidine Phosphotransfer Proteins in Fungal Two-Component Signal Transduction Pathways
2013-01-01
The histidine phosphotransfer (HPt) protein Ypd1 is an important participant in the Saccharomyces cerevisiae multistep two-component signal transduction pathway and, unlike the expanded histidine kinase gene family, is encoded by a single gene in nearly all model and pathogenic fungi. Ypd1 is essential for viability in both S. cerevisiae and in Cryptococcus neoformans. These and other aspects of Ypd1 biology, combined with the availability of structural and mutational data in S. cerevisiae, s...
A Possible Two-Component Structure of the Non-Perturbative Pomeron
Gauron, P; Gauron, Pierre; Nicolescu, Basarab
2000-01-01
We propose a QCD-inspired two-component Pomeron form which gives an excellent description of the proton-proton, pi-proton, kaon-proton, gamma-proton and gamma-gamma total cross sections. Our fit has a better CHI2/dof for a smaller number of parameters as compared with the PDG fit. Our 2-Pomeron form is fully compatible with weak Regge exchange-degeneracy, universality, Regge factorization and the generalized vector dominance model.
Modelling and simulation of thermal power plants
Energy Technology Data Exchange (ETDEWEB)
Eborn, J.
1998-02-01
Mathematical modelling and simulation are important tools when dealing with engineering systems that today are becoming increasingly more complex. Integrated production and recycling of materials are trends that give rise to heterogenous systems, which are difficult to handle within one area of expertise. Model libraries are an excellent way to package engineering knowledge of systems and units to be reused by those who are not experts in modelling. Many commercial packages provide good model libraries, but they are usually domain-specific and closed. Heterogenous, multi-domain systems requires open model libraries written in general purpose modelling languages. This thesis describes a model database for thermal power plants written in the object-oriented modelling language OMOLA. The models are based on first principles. Subunits describe volumes with pressure and enthalpy dynamics and flows of heat or different media. The subunits are used to build basic units such as pumps, valves and heat exchangers which can be used to build system models. Several applications are described; a heat recovery steam generator, equipment for juice blending, steam generation in a sulphuric acid plant and a condensing steam plate heat exchanger. Model libraries for industrial use must be validated against measured data. The thesis describes how parameter estimation methods can be used for model validation. Results from a case-study on parameter optimization of a non-linear drum boiler model show how the technique can be used 32 refs, 21 figs
Modeling Thermal Dust Emission and Implications
Liang, Zhuohan
2014-01-01
An accurate model of thermal dust emission at the far-infrared and millimeter wavelengths is important for studying the cosmic microwave background anisotropies and for understanding the cycling of matter and energy between stars and the interstellar medium. I will present results of fitting all-sky one-component dust models with fixed or variable emissivity spectral index to the 210-channel dust spectra from the COBE-FIRAS, the 100 - 240 μm maps from the COBE-DIRBE, and the 94 GHz dust map from the WMAP. I will also discuss the implications of the analysis on understanding astrophysical processes and the physical properties of dust grains.
Stochastic modeling of thermal fatigue crack growth
Radu, Vasile
2015-01-01
The book describes a systematic stochastic modeling approach for assessing thermal-fatigue crack-growth in mixing tees, based on the power spectral density of temperature fluctuation at the inner pipe surface. It shows the development of a frequency-temperature response function in the framework of single-input, single-output (SISO) methodology from random noise/signal theory under sinusoidal input. The frequency response of stress intensity factor (SIF) is obtained by a polynomial fitting procedure of thermal stress profiles at various instants of time. The method, which takes into account the variability of material properties, and has been implemented in a real-world application, estimates the probabilities of failure by considering a limit state function and Monte Carlo analysis, which are based on the proposed stochastic model. Written in a comprehensive and accessible style, this book presents a new and effective method for assessing thermal fatigue crack, and it is intended as a concise and practice-or...
Trapping of two-component matter-wave solitons by mismatched optical lattices
Energy Technology Data Exchange (ETDEWEB)
Shi, Z.; Law, K.J.H. [Department of Mathematics and Statistics, University of Massachusetts, Amherst, MA 01003-4515 (United States); Kevrekidis, P.G. [Department of Mathematics and Statistics, University of Massachusetts, Amherst, MA 01003-4515 (United States)], E-mail: kevrekid@gmail.com; Malomed, B.A. [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978 (Israel)
2008-05-26
We consider a one-dimensional model of a two-component Bose-Einstein condensate in the presence of periodic external potentials of opposite signs, acting on the two species. The interaction between the species is attractive, while intra-species interactions may be attractive too [the system of the bright-bright (BB) type], or of opposite signs in the two components [the gap-bright (GB) type]. We identify the existence and stability domains for soliton complexes of the BB and GB types. The evolution of unstable solitons leads to the establishment of oscillatory states. The increase of the strength of the nonlinear attraction between the species results in symbiotic stabilization of the complexes, despite the fact that one component is centered around a local maximum of the respective periodic potential.
Casino, Patricia; Rubio, Vicente; Marina, Alberto
2009-10-16
The chief mechanism used by bacteria for sensing their environment is based on two conserved proteins: a sensor histidine kinase (HK) and an effector response regulator (RR). The signal transduction process involves highly conserved domains of both proteins that mediate autokinase, phosphotransfer, and phosphatase activities whose output is a finely tuned RR phosphorylation level. Here, we report the structure of the complex between the entire cytoplasmic portion of Thermotoga maritima class I HK853 and its cognate, RR468, as well as the structure of the isolated RR468, both free and BeF(3)(-) bound. Our results provide insight into partner specificity in two-component systems, recognition of the phosphorylation state of each partner, and the catalytic mechanism of the phosphatase reaction. Biochemical analysis shows that the HK853-catalyzed autokinase reaction proceeds by a cis autophosphorylation mechanism within the HK subunit. The results suggest a model for the signal transduction mechanism in two-component systems.
A hydrodynamic scheme for two-component winds from hot stars
Votruba, V; Kubát, J; Rätzel, D
2007-01-01
We have developed a time-dependent two-component hydrodynamics code to simulate radiatively-driven stellar winds from hot stars. We use a time-explicit van Leer scheme to solve the hydrodynamic equations of a two-component stellar wind. Dynamical friction due to Coulomb collisions between the passive bulk plasma and the line-scattering ions is treated by a time-implicit, semi-analytic method using a polynomial fit to the Chandrasekhar function. This gives stable results despite the stiffness of the problem. This method was applied to model stars with winds that are both poorly and well-coupled. While for the former case we reproduce the mCAK solution, for the latter case our solution leads to wind decoupling.
Saturn Ring Data Analysis and Thermal Modeling
Dobson, Coleman
2011-01-01
CIRS, VIMS, UVIS, and ISS (Cassini's Composite Infrared Specrtometer, Visual and Infrared Mapping Spectrometer, Ultra Violet Imaging Spectrometer and Imaging Science Subsystem, respectively), have each operated in a multidimensional observation space and have acquired scans of the lit and unlit rings at multiple phase angles. To better understand physical and dynamical ring particle parametric dependence, we co-registered profiles from these three instruments, taken at a wide range of wavelengths, from ultraviolet through the thermal infrared, to associate changes in ring particle temperature with changes in observed brightness, specifically with albedos inferred by ISS, UVIS and VIMS. We work in a parameter space where the solar elevation range is constrained to 12 deg - 14 deg and the chosen radial region is the B3 region of the B ring; this region is the most optically thick region in Saturn's rings. From this compilation of multiple wavelength data, we construct and fit phase curves and color ratios using independent dynamical thermal models for ring structure and overplot Saturn, Saturn ring, and Solar spectra. Analysis of phase curve construction and color ratios reveals thermal emission to fall within the extrema of the ISS bandwidth and a geometrical dependence of reddening on phase angle, respectively. Analysis of spectra reveals Cassini CIRS Saturn spectra dominate Cassini CIRS B3 Ring Spectra from 19 to 1000 microns, while Earth-based B Ring Spectrum dominates Earth-based Saturn Spectrum from 0.4 to 4 microns. From our fits we test out dynamical thermal models; from the phase curves we derive ring albedos and non-lambertian properties of the ring particle surfaces; and from the color ratios we examine multiple scattering within the regolith of ring particles.
Marton, F. C.
2001-12-01
The thermal, mineralogical, and buoyancy structures of thermal-kinetic models of subducting slabs are highly dependent upon a number of parameters, especially if the metastable persistence of olivine in the transition zone is investigated. The choice of starting thermal model for the lithosphere, whether a cooling halfspace (HS) or plate model, can have a significant effect, resulting in metastable wedges of olivine that differ in size by up to two to three times for high values of the thermal parameter (ǎrphi). Moreover, as ǎrphi is the product of the age of the lithosphere at the trench, convergence rate, and dip angle, slabs with similar ǎrphis can show great variations in structures as these constituents change. This is especially true for old lithosphere, as the lithosphere continually cools and thickens with age for HS models, but plate models, with parameters from Parson and Sclater [1977] (PS) or Stein and Stein [1992] (GDH1), achieve a thermal steady-state and constant thickness in about 70 My. In addition, the latent heats (q) of the phase transformations of the Mg2SiO4 polymorphs can also have significant effects in the slabs. Including q feedback in models raises the temperature and reduces the extent of metastable olivine, causing the sizes of the metastable wedges to vary by factors of up to two times. The effects of the choice of thermal model, inclusion and non-inclusion of q feedback, and variations in the constituents of ǎrphi are investigated for several model slabs.
The CpxRA two-component system is essential for Citrobacter rodentium virulence.
Thomassin, Jenny-Lee; Giannakopoulou, Natalia; Zhu, Lei; Gross, Jeremy; Salmon, Kristiana; Leclerc, Jean-Mathieu; Daigle, France; Le Moual, Hervé; Gruenheid, Samantha
2015-05-01
Citrobacter rodentium is a murine intestinal pathogen used as a model for the foodborne human pathogens enterohemorrhagic Escherichia coli and enteropathogenic E. coli. During infection, these pathogens use two-component signal transduction systems to detect and adapt to changing environmental conditions. In E. coli, the CpxRA two-component signal transduction system responds to envelope stress by modulating the expression of a myriad of genes. Quantitative real-time PCR showed that cpxRA was expressed in the colon of C57BL/6J mice infected with C. rodentium. To determine whether CpxRA plays a role during C. rodentium infection, a cpxRA deletion strain was generated and found to have a colonization defect during infection. This defect was independent of an altered growth rate or a defective type III secretion system, and single-copy chromosomal complementation of cpxRA restored virulence. The C. rodentium strains were then tested in C3H/HeJ mice, a lethal intestinal infection model. Mice infected with the ΔcpxRA strain survived infection, whereas mice infected with the wild-type or complemented strains succumbed to infection. Furthermore, we found that the cpxRA expression level was higher during early infection than at a later time point. Taken together, these data demonstrate that the CpxRA two-component signal transduction system is essential for the in vivo virulence of C. rodentium. In addition, these data suggest that fine-tuned cpxRA expression is important for infection. This is the first study that identifies a C. rodentium two-component transduction system required for pathogenesis. This study further indicates that CpxRA is an interesting target for therapeutics against enteric pathogens.
Aqueous Solution Vessel Thermal Model Development II
Energy Technology Data Exchange (ETDEWEB)
Buechler, Cynthia Eileen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-10-28
The work presented in this report is a continuation of the work described in the May 2015 report, “Aqueous Solution Vessel Thermal Model Development”. This computational fluid dynamics (CFD) model aims to predict the temperature and bubble volume fraction in an aqueous solution of uranium. These values affect the reactivity of the fissile solution, so it is important to be able to calculate them and determine their effects on the reaction. Part A of this report describes some of the parameter comparisons performed on the CFD model using Fluent. Part B describes the coupling of the Fluent model with a Monte-Carlo N-Particle (MCNP) neutron transport model. The fuel tank geometry is the same as it was in the May 2015 report, annular with a thickness-to-height ratio of 0.16. An accelerator-driven neutron source provides the excitation for the reaction, and internal and external water cooling channels remove the heat. The model used in this work incorporates the Eulerian multiphase model with lift, wall lubrication, turbulent dispersion and turbulence interaction. The buoyancy-driven flow is modeled using the Boussinesq approximation, and the flow turbulence is determined using the k-ω Shear-Stress-Transport (SST) model. The dispersed turbulence multiphase model is employed to capture the multiphase turbulence effects.
Directory of Open Access Journals (Sweden)
Masaru Ishizuka
2011-01-01
Full Text Available In recent years, there is a growing demand to have smaller and lighter electronic circuits which have greater complexity, multifunctionality, and reliability. High-density multichip packaging technology has been used in order to meet these requirements. The higher the density scale is, the larger the power dissipation per unit area becomes. Therefore, in the designing process, it has become very important to carry out the thermal analysis. However, the heat transport model in multichip modules is very complex, and its treatment is tedious and time consuming. This paper describes an application of the thermal network method to the transient thermal analysis of multichip modules and proposes a simple model for the thermal analysis of multichip modules as a preliminary thermal design tool. On the basis of the result of transient thermal analysis, the validity of the thermal network method and the simple thermal analysis model is confirmed.
Multidimensional thermal-chemical cookoff modeling
Energy Technology Data Exchange (ETDEWEB)
Baer, M.R.; Gross, R.J.; Gartling, D.K.; Hobbs, M.L.
1994-08-01
Multidimensional thermal/chemical modeling is an essential step in the development of a predictive capability for cookoff of energetic materials in systems subjected to abnormal thermal environments. COYOTE II is a state-of-the-art two- and three-dimensional finite element code for the solution of heat conduction problems including surface-to-surface thermal radiation heat transfer and decomposition chemistry. Multistep finite rate chemistry is incorporated into COYOTE II using an operator-splitting methodology; rate equations are solved element-by-element with a modified matrix-free stiff solver, CHEMEQ. COYOTE II is purposely designed with a user-oriented input structure compatible with the database, the pre-processing mesh generation, and the post-processing tools for data visualization shared with other engineering analysis codes available at Sandia National Laboratories. As demonstrated in a companion paper, decomposition during cookoff in a confined or semi-confined system leads to significant mechanical behavior. Although mechanical effect are not presently considered in COYOTE II, the formalism for including mechanics in multidimensions is under development.
Modeling and Thermal Analysis of Disc
Brake Praveena S; Lava Kumar M
2014-01-01
The disc brake is a device used for slowing or stopping the rotation of the vehicle. Number of times using the brake for vehicle leads to heat generation during braking event, such that disc brake undergoes breakage due to high Temperature. Disc brake model is done by CATIA and analysis is done by using ANSYS workbench. The main purpose of this project is to study the Thermal analysis of the Materials for the Aluminum, Grey Cast Iron, HSS M42, and HSS M2. A comparison between ...
Bioinformatics analysis of two-component regulatory systems in Staphylococcus epidermidis
Institute of Scientific and Technical Information of China (English)
QIN Zhiqiang; ZHONG Yang; ZHANG Jian; HE Youyu; WU Yang; JIANG Juan; CHEN Jiemin; LUO Xiaomin; QU Di
2004-01-01
Sixteen pairs of two-component regulatory systems are identified in the genome of Staphylococcus epidermidis ATCC12228 strain, which is newly sequenced by our laboratory for Medical Molecular Virology and Chinese National Human Genome Center at Shanghai, by using bioinformatics analysis. Comparative analysis of the twocomponent regulatory systems in S. epidermidis and that of S.aureus and Bacillus subtilis shows that these systems may regulate some important biological functions, e.g. growth,biofilm formation, and expression of virulence factors in S.epidermidis. Two conserved domains, i.e. HATPase_c and REC domains, are found in all 16 pairs of two-component proteins.Homologous modelling analysis indicates that there are 4similar HATPase_c domain structures of histidine kinases and 13 similar REC domain structures of response regulators,and there is one AMP-PNP binding pocket in the HATPase_c domain and three active aspartate residues in the REC domain. Preliminary experiment reveals that the bioinformatics analysis of the conserved domain structures in the two-component regulatory systems in S. epidermidis may provide useful information for discovery of potential drug target.
Asteroid thermal modeling in the presence of reflected sunlight
Myhrvold, Nathan
2016-10-01
This study addresses thermal modeling of asteroids with a new derivation of the Near Earth Asteroid Thermal (NEATM) model which correctly accounts for the presence of reflected sunlight in short wave IR bands. Kirchhoff's law of thermal radiation applies to this case and has important implications. New insight is provided into the ???? parameter in the NEATM model and it is extended to thermal models besides NEATM. The role of surface material properties on ???? is examined using laboratory spectra of meteorites and other asteroid compositional proxies; the common assumption that emissivity ????=0.9 in asteroid thermal models may not be justified and can lead to misestimating physical parameters. In addition, indeterminacy in thermal modeling can limit its ability to uniquely determine temperature and other physical properties. A new curve-fitting approach allows thermal modeling to be done independently of visible-band observational parameters, such as the absolute magnitude ????.
Sommer, W.T.
2015-01-01
Modelling and monitoring of Aquifer Thermal Energy Storage Impacts of heterogeneity, thermal interference and bioremediation Wijbrand Sommer
PhD thesis, Wageningen University, Wageningen, NL (2015)
ISBN 978-94-6257-294-2 Abstract Aquifer thermal energy storage (ATES) is
In-situ measurements of material thermal parameters for accurate LED lamp thermal modelling
Vellvehi, M.; Perpina, X.; Jorda, X.; Werkhoven, R.J.; Kunen, J.M.G.; Jakovenko, J.; Bancken, P.; Bolt, P.J.
2013-01-01
This work deals with the extraction of key thermal parameters for accurate thermal modelling of LED lamps: air exchange coefficient around the lamp, emissivity and thermal conductivity of all lamp parts. As a case study, an 8W retrofit lamp is presented. To assess simulation results, temperature is
In-situ measurements of material thermal parameters for accurate LED lamp thermal modelling
Vellvehi, M.; Perpina, X.; Jorda, X.; Werkhoven, R.J.; Kunen, J.M.G.; Jakovenko, J.; Bancken, P.; Bolt, P.J.
2013-01-01
This work deals with the extraction of key thermal parameters for accurate thermal modelling of LED lamps: air exchange coefficient around the lamp, emissivity and thermal conductivity of all lamp parts. As a case study, an 8W retrofit lamp is presented. To assess simulation results, temperature is
Sommer, W.T.
2015-01-01
Modelling and monitoring of Aquifer Thermal Energy Storage Impacts of heterogeneity, thermal interference and bioremediation Wijbrand Sommer
PhD thesis, Wageningen University, Wageningen, NL (2015)
ISBN 978-94-6257-294-2 Abstract Aquifer thermal energy storage (ATES) is
Predictions of Phase Distribution in Liquid-Liquid Two-Component Flow
Wang, Xia; Sun, Xiaodong; Duval, Walter M.
2011-06-01
Ground-based liquid-liquid two-component flow can be used to study reduced-gravity gas-liquid two-phase flows provided that the two liquids are immiscible with similar densities. In this paper, we present a numerical study of phase distribution in liquid-liquid two-component flows using the Eulerian two-fluid model in FLUENT, together with a one-group interfacial area transport equation (IATE) that takes into account fluid particle interactions, such as coalescence and disintegration. This modeling approach is expected to dynamically capture changes in the interfacial structure. We apply the FLUENT-IATE model to a water-Therminol 59® two-component vertical flow in a 25-mm inner diameter pipe, where the two liquids are immiscible with similar densities (3% difference at 20°C). This study covers bubbly (drop) flow and bubbly-to-slug flow transition regimes with area-averaged void (drop) fractions from 3 to 30%. Comparisons of the numerical results with the experimental data indicate that for bubbly flows, the predictions of the lateral phase distributions using the FLUENT-IATE model are generally more accurate than those using the model without the IATE. In addition, we demonstrate that the coalescence of fluid particles is dominated by wake entrainment and enhanced by increasing either the continuous or dispersed phase velocity. However, the predictions show disagreement with experimental data in some flow conditions for larger void fraction conditions, which fall into the bubbly-to-slug flow transition regime. We conjecture that additional fluid particle interaction mechanisms due to the change of flow regimes are possibly involved.
Bioadhesion to model thermally responsive surfaces
Andrzejewski, Brett Paul
This dissertation focuses on the characterization of two surfaces: mixed self-assembled monolayers (SAMs) of hexa(ethylene glycol) and alkyl thiolates (mixed SAM) and poly(N-isopropylacrylamide) (PNIPAAm). The synthesis of hexa(ethylene gylcol) alkyl thiol (C11EG 6OH) is presented along with the mass spectrometry and nuclear magnetic resonance results. The gold substrates were imaged prior to SAM formation with atomic force micrscopy (AFM). Average surface roughness of the gold substrate was 0.44 nm, 0.67 nm, 1.65 nm for 15, 25 and 60 nm gold thickness, respectively. The height of the mixed SAM was measured by ellipsometry and varied from 13 to 28°A depending on surface mole fraction of C11EG6OH. The surface mole fraction of C11EG6OH for the mixed SAM was determined by X-ray photoelectron spectroscopy (XPS) with optimal thermal responsive behavior in the range of 0.4 to 0.6. The mixed SAM surface was confirmed to be thermally responsive by contact angle goniometry, 35° at 28°C and ˜55° at 40°C. In addition, the mixed SAM surfaces were confirmed to be thermally responsive for various aqueous mediums by tensiometry. Factors such as oxygen, age, and surface mole fraction and how they affect the thermal responsive of the mixed SAM are discussed. Lastly, rat fibroblasts were grown on the mixed SAM and imaged by phase contrast microscopy to show inhibition of attachment at temperatures below the molecular transition. Qualitative and quantitative measurements of the fibroblast adhesion data are provided that support the hypothesis of the mixed SAM exhibits a dominantly non-fouling molecular conformation at 25°C whereas it exhibits a dominantly fouling molecular conformation at 40°C. The adhesion of six model proteins: bovine serum albumin, collagen, pyruvate kinase, cholera toxin subunit B, ribonuclease, and lysozyme to the model thermally responsive mixed SAM were examined using AFM. All six proteins possessed adhesion to the pure component alkyl thiol, in
Modelling of thermal processes in indoor icerinks
Energy Technology Data Exchange (ETDEWEB)
Korsgaard, V.; Forowicz, A.
1986-01-01
Heat transfer by radiation between ceiling and ice and high humidity of air in indoor icerinks very often cause heavy condensation on the ceiling or roof construction, which has some bad effects. To check how often condensation will occur and possible ways of preventing condensation, a simple computer model of the thermal processes taking place in an indoor icerink was eleborated. The assumptions being made concerning the model system geometry as well as the mathematical problem formulation are described. Next, the mathematical model of the problem being considered, the method of solution and the short description of the simulation program are presented. The report shows further the results obtained from several executions of the program using different data regarding changes in the model itself as well as the influence of different ventilation rates, heat input by radiation and convection etc. These results have allowed for general comparison between four cases, i.e. between the model icerink with a ceiling made from ordinary building material, with a bright aluminium foil glued to the ceiling surface and with a suspended shield of corrugated bright aluminium plates installed below the roof construction, which surface facing the roof is unpainted or painted to increase its absorptivity.
Model for thermal conductivity of CNT-nanofluids
Indian Academy of Sciences (India)
H E Patel; K B Anoop; T Sundararajan; Sarit K Das
2008-06-01
This work presents a simple model for predicting the thermal conductivity of carbon nanotube (CNT) nanofluids. Effects due to the high thermal conductivity of CNTs and the percolation of heat through it are considered to be the most important reasons for their anomalously high thermal conductivity enhancement. A new approach is taken for the modeling, the novelty of which lies in the prediction of the thermal behaviour of oil based as well as water based CNT nanofluids, which are quite different from each other in thermal characteristics. The model is found to correctly predict the trends observed in experimental data for different combinations of CNT nanofluids with varying concentrations.
A neural network evaluation model for individual thermal comfort
Energy Technology Data Exchange (ETDEWEB)
Liu, Weiwei; Lian, Zhiwei; Zhao, Bo [Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai 200240 (China)
2007-10-15
An evaluation model for individual thermal comfort is presented based on the BP neural network. The train data came from a thermal comfort survey. The evaluation results of the model showed a good match with the subject's real thermal sensation, which indicated that the model can be used to evaluate individual thermal comfort rightly. Taken a room air conditioner as an example, the application of the NNEM in creating a microenvironment for individual was discussed. The result showed that the NNEM can play an important role of connecting individual thermal comfort with the control on the air conditioner. (author)
Topological phases of two-component bosons in species-dependent artificial gauge potentials
Wu, Ying-Hai; Shi, Tao
2016-08-01
We study bosonic atoms with two internal states in artificial gauge potentials whose strengths are different for the two components. A series of topological phases for such systems is proposed using the composite fermion theory and the parton construction. It is found in exact diagonalization that some of the proposed states may be realized for simple contact interaction between bosons. The ground states and low-energy excitations of these states are modeled using trial wave functions. The effective field theories for these states are also constructed and reveal some interesting properties.
Numerical simulation of two-component flow fluid - fluid in the microchannel T- type
Directory of Open Access Journals (Sweden)
Shebeleva A.A.
2015-01-01
Full Text Available Results of testing methodology for calculating two-phase flows based on the method of fluid in the cells (VOF method, and the procedure for CSF accounting of surface tension forces in the microchannel are considered in the work. Mathematical modeling of two-component flow fluid -fluid in the T- microchannel conducted using this methodology. The following flow regimes studied slug flow, rivulet flow, parallel flow, dispersed (droplet flow, plug flow. Comparison of numerical results with experimental data done. Satisfactory agreement between the calculated values with the experimental data obtained.
A first-order thermal model for building design
Energy Technology Data Exchange (ETDEWEB)
Mathews, E.H. [Centre for Experimental and Numerical Thermoflow, Univ. of Pretoria (South Africa); Richards, P.G. [Centre for Experimental and Numerical Thermoflow, Univ. of Pretoria (South Africa); Lombard, C. [Centre for Experimental and Numerical Thermoflow, Univ. of Pretoria (South Africa)
1994-12-31
Simplified thermal models of buildings can successfully be applied in building design. This paper describes the derivation and validation of a first-order thermal model which has a clear physical interpretation, is based on uncomplicated calculation procedures and requires limited input information. Because extensive simplifications and assumptions are inherent in the development of the model, a comprehensive validation study is reported. The validity of the thermal model was proven with 70 validation studies in 32 buildings comprising a wide range of thermal characteristics. The accuracy of predictions compares well with other sophisticated programs. The proposed model is considered to be eminently suitable for incorporation in an efficient design tool. (orig.)
Evaluation of Infrared Images by Using a Human Thermal Model
2001-10-25
thermal environmental history have been recorded. In this case, the thermal environmental history could be estimated from the behavior of a subject... environmental history and physiological condition history. An advantage of the evaluation of IR images using the thermal model is to provide
Development of the GPM Observatory Thermal Vacuum Test Model
Yang, Kan; Peabody, Hume
2012-01-01
A software-based thermal modeling process was documented for generating the thermal panel settings necessary to simulate worst-case on-orbit flight environments in an observatory-level thermal vacuum test setup. The method for creating such a thermal model involved four major steps: (1) determining the major thermal zones for test as indicated by the major dissipating components on the spacecraft, then mapping the major heat flows between these components; (2) finding the flight equivalent sink temperatures for these test thermal zones; (3) determining the thermal test ground support equipment (GSE) design and initial thermal panel settings based on the equivalent sink temperatures; and (4) adjusting the panel settings in the test model to match heat flows and temperatures with the flight model. The observatory test thermal model developed from this process allows quick predictions of the performance of the thermal vacuum test design. In this work, the method described above was applied to the Global Precipitation Measurement (GPM) core observatory spacecraft, a joint project between NASA and the Japanese Aerospace Exploration Agency (JAXA) which is currently being integrated at NASA Goddard Space Flight Center for launch in Early 2014. From preliminary results, the thermal test model generated from this process shows that the heat flows and temperatures match fairly well with the flight thermal model, indicating that the test model can simulate fairly accurately the conditions on-orbit. However, further analysis is needed to determine the best test configuration possible to validate the GPM thermal design before the start of environmental testing later this year. Also, while this analysis method has been applied solely to GPM, it should be emphasized that the same process can be applied to any mission to develop an effective test setup and panel settings which accurately simulate on-orbit thermal environments.
PHASE TRANSITION PROPERTIES OF A TWO COMPONENT FINITE MAGNETIC SUPERLATTICE
Institute of Scientific and Technical Information of China (English)
WANG XIAO-GUANG; LIU NING-NING; PAN SHAO-HUA; YANG GUO-ZHEN
2000-01-01
We study an (l, n) finite superlattice, which consists of two alternative magnetic materials(components) of l and n atomic layers, respectively. Based on the Ising model, we examine the phase transition properties of the magnetic superlattice. By transfer matrix method we derive the equation for Curie temperature of the superlattice. Numerical results are obtained for the dependence of Curie temperature on the thickness and exchange constants of the superlattice.
Argonne Bubble Experiment Thermal Model Development II
Energy Technology Data Exchange (ETDEWEB)
Buechler, Cynthia Eileen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-07-01
This report describes the continuation of the work reported in “Argonne Bubble Experiment Thermal Model Development”. The experiment was performed at Argonne National Laboratory (ANL) in 2014. A rastered 35 MeV electron beam deposited power in a solution of uranyl sulfate, generating heat and radiolytic gas bubbles. Irradiations were performed at three beam power levels, 6, 12 and 15 kW. Solution temperatures were measured by thermocouples, and gas bubble behavior was observed. This report will describe the Computational Fluid Dynamics (CFD) model that was developed to calculate the temperatures and gas volume fractions in the solution vessel during the irradiations. The previous report described an initial analysis performed on a geometry that had not been updated to reflect the as-built solution vessel. Here, the as-built geometry is used. Monte-Carlo N-Particle (MCNP) calculations were performed on the updated geometry, and these results were used to define the power deposition profile for the CFD analyses, which were performed using Fluent, Ver. 16.2. CFD analyses were performed for the 12 and 15 kW irradiations, and further improvements to the model were incorporated, including the consideration of power deposition in nearby vessel components, gas mixture composition, and bubble size distribution. The temperature results of the CFD calculations are compared to experimental measurements.
Rocketdyne/Westinghouse nuclear thermal rocket engine modeling
Glass, James F.
1993-01-01
The topics are presented in viewgraph form and include the following: systems approach needed for nuclear thermal rocket (NTR) design optimization; generic NTR engine power balance codes; rocketdyne nuclear thermal system code; software capabilities; steady state model; NTR engine optimizer code-logic; reactor power calculation logic; sample multi-component configuration; NTR design code output; generic NTR code at Rocketdyne; Rocketdyne NTR model; and nuclear thermal rocket modeling directions.
Absolutely stable solitons in two-component active systems
Malomed, B A; Malomed, Boris; Winful, Herbert
1995-01-01
As is known, a solitary pulse in the complex cubic Ginzburg-Landau (GL) equation is unstable. We demonstrate that a system of two linearly coupled GL equations with gain and dissipation in one subsystem and pure dissipation in another produces absolutely stable solitons and their bound states. The problem is solved in a fully analytical form by means of the perturbation theory. The soliton coexists with a stable trivial state; there is also an unstable soliton with a smaller amplitude, which is a separatrix between the two stable states. This model has a direct application in nonlinear fiber optics, describing an Erbium-doped laser based on a dual-core fiber.
Mckim, Stephen A.
2016-01-01
This thesis describes the development and correlation of a thermal model that forms the foundation of a thermal capacitance spacecraft propellant load estimator. Specific details of creating the thermal model for the diaphragm propellant tank used on NASA's Magnetospheric Multiscale spacecraft using ANSYS and the correlation process implemented are presented. The thermal model was correlated to within plus or minus 3 degrees Celsius of the thermal vacuum test data, and was determined sufficient to make future propellant predictions on MMS. The model was also found to be relatively sensitive to uncertainties in applied heat flux and mass knowledge of the tank. More work is needed to improve temperature predictions in the upper hemisphere of the propellant tank where predictions were found to be 2 to 2.5 C lower than the test data. A road map for applying the model to predict propellant loads on the actual MMS spacecraft toward its end of life in 2017-2018 is also presented.
Liu, Feifei; Lan, Fengchong; Chen, Jiqing
2016-07-01
Heat pipe cooling for battery thermal management systems (BTMSs) in electric vehicles (EVs) is growing due to its advantages of high cooling efficiency, compact structure and flexible geometry. Considering the transient conduction, phase change and uncertain thermal conditions in a heat pipe, it is challenging to obtain the dynamic thermal characteristics accurately in such complex heat and mass transfer process. In this paper, a "segmented" thermal resistance model of a heat pipe is proposed based on thermal circuit method. The equivalent conductivities of different segments, viz. the evaporator and condenser of pipe, are used to determine their own thermal parameters and conditions integrated into the thermal model of battery for a complete three-dimensional (3D) computational fluid dynamics (CFD) simulation. The proposed "segmented" model shows more precise than the "non-segmented" model by the comparison of simulated and experimental temperature distribution and variation of an ultra-thin micro heat pipe (UMHP) battery pack, and has less calculation error to obtain dynamic thermal behavior for exact thermal design, management and control of heat pipe BTMSs. Using the "segmented" model, the cooling effect of the UMHP pack with different natural/forced convection and arrangements is predicted, and the results correspond well to the tests.
Thermal Conductivity in Suspension Sprayed Thermal Barrier Coatings: Modeling and Experiments
Ganvir, Ashish; Kumara, Chamara; Gupta, Mohit; Nylen, Per
2016-12-01
Axial suspension plasma spraying (ASPS) can generate microstructures with higher porosity and pores in the size range from submicron to nanometer. ASPS thermal barrier coatings (TBC) have already shown a great potential to produce low thermal conductivity coatings for gas turbine applications. It is important to understand the fundamental relationships between microstructural defects in ASPS coatings such as crystallite boundaries, porosity etc. and thermal conductivity. Object-oriented finite element (OOF) analysis has been shown as an effective tool for evaluating thermal conductivity of conventional TBCs as this method is capable of incorporating the inherent microstructure in the model. The objective of this work was to analyze the thermal conductivity of ASPS TBCs using experimental techniques and also to evaluate a procedure where OOF can be used to predict and analyze the thermal conductivity for these coatings. Verification of the model was done by comparing modeling results with the experimental thermal conductivity. The results showed that the varied scaled porosity has a significant influence on the thermal conductivity. Smaller crystallites and higher overall porosity content resulted in lower thermal conductivity. It was shown that OOF could be a powerful tool to predict and rank thermal conductivity of ASPS TBCs.
Thermal Conductivity in Suspension Sprayed Thermal Barrier Coatings: Modeling and Experiments
Ganvir, Ashish; Kumara, Chamara; Gupta, Mohit; Nylen, Per
2017-01-01
Axial suspension plasma spraying (ASPS) can generate microstructures with higher porosity and pores in the size range from submicron to nanometer. ASPS thermal barrier coatings (TBC) have already shown a great potential to produce low thermal conductivity coatings for gas turbine applications. It is important to understand the fundamental relationships between microstructural defects in ASPS coatings such as crystallite boundaries, porosity etc. and thermal conductivity. Object-oriented finite element (OOF) analysis has been shown as an effective tool for evaluating thermal conductivity of conventional TBCs as this method is capable of incorporating the inherent microstructure in the model. The objective of this work was to analyze the thermal conductivity of ASPS TBCs using experimental techniques and also to evaluate a procedure where OOF can be used to predict and analyze the thermal conductivity for these coatings. Verification of the model was done by comparing modeling results with the experimental thermal conductivity. The results showed that the varied scaled porosity has a significant influence on the thermal conductivity. Smaller crystallites and higher overall porosity content resulted in lower thermal conductivity. It was shown that OOF could be a powerful tool to predict and rank thermal conductivity of ASPS TBCs.
Instabilities in relativistic two-component (super)fluids
Haber, Alexander; Stetina, Stephan
2016-01-01
We study two-fluid systems with nonzero fluid velocities and compute their sound modes, which indicate various instabilities. For the case of two zero-temperature superfluids we employ a microscopic field-theoretical model of two coupled bosonic fields, including an entrainment coupling and a non-entrainment coupling. We analyse the onset of the various instabilities systematically and point out that the dynamical two-stream instability can only occur beyond Landau's critical velocity, i.e., in an already energetically unstable regime. A qualitative difference is found for the case of two normal fluids, where certain transverse modes suffer a two-stream instability in an energetically stable regime if there is entrainment between the fluids. Since we work in a fully relativistic setup, our results are very general and of potential relevance for (super)fluids in neutron stars and, in the non-relativistic limit of our results, in the laboratory.
Thermal modelling of a torpedo-car
Directory of Open Access Journals (Sweden)
Verdeja-González, L. F.
2005-12-01
Full Text Available A two-dimensional finite element model for computing the temperature distribution in a torpedo-car holding pig iron is described in this work. The model determines the temperature gradients in steady and transient conditions within the different parts that constitute the system, which are considered to be the steel casing, refractory lining, liquid iron, slag and air. Heat transfer within the main fluid phases (iron and air is computed assuming an apparent thermal conductivity term incorporating the contribution from convection and radiation, and it is affected by the dimensions of the vessel. Thermal gradients within the constituents of the torpedo-car are used to calculate heat losses during operation. It was found that the model required the incorporation of a region within the iron-refractory interface to reproduce thermographic data recorded during operation; the heat transfer coefficient of this interface was found to be equal to 30 Wm^{-2}K^{-1}.
En este trabajo se describe un modelo bidimensional basado en el método del elemento finito para calcular la distribución de temperaturas en un carro torpedo lleno de arrabio. El modelo determina los gradientes térmicos en condiciones estacionarias y transitorias dentro de las partes que constituyen el sistema considerado, como son cubierta de acero, recubrimientos refractarios, arrabio líquido, escoria y aire. La transferencia de calor en las fases fluidas (arrabio y aire se calcula suponiendo un coeficiente de conductividad térmica aparente que incorpora las contribuciones por convección y radiación y está afectado por las dimensiones del recipiente. El conocimiento de los gradientes térmicos permite calcular las pérdidas de calor durante la operación del carro. Se encontró que el modelo requiere de la incorporación de una región en la intercara hierro-refractario para reproducir la información termográfica recopilada durante pruebas en planta. El
Two-component jet simulations: I. Topological stability of analytical MHD outflow solutions
Matsakos, T; Vlahakis, N; Massaglia, S; Mignone, A; Trussoni, E
2007-01-01
Observations of collimated outflows in young stellar objects indicate that several features of the jets can be understood by adopting the picture of a two-component outflow, wherein a central stellar component around the jet axis is surrounded by an extended disk-wind. The precise contribution of each component may depend on the intrinsic physical properties of the YSO-disk system as well as its evolutionary stage. In this context, the present article starts a systematic investigation of two-component jet models via time-dependent simulations of two prototypical and complementary analytical solutions, each closely related to the properties of stellar-outflows and disk-winds. These models describe a meridionally and a radially self-similar exact solution of the steady-state, ideal hydromagnetic equations, respectively. By using the PLUTO code to carry out the simulations, the study focuses on the topological stability of each of the two analytical solutions, which are successfully extended to all space by remo...
Numerical analysis of a non equilibrium two-component two-compressible flow in porous media
Saad, Bilal Mohammed
2013-09-01
We propose and analyze a finite volume scheme to simulate a non equilibrium two components (water and hydrogen) two phase flow (liquid and gas) model. In this model, the assumption of local mass non equilibrium is ensured and thus the velocity of the mass exchange between dissolved hydrogen and hydrogen in the gas phase is supposed finite. The proposed finite volume scheme is fully implicit in time together with a phase-by-phase upwind approach in space and it is discretize the equations in their general form with gravity and capillary terms We show that the proposed scheme satisfies the maximum principle for the saturation and the concentration of the dissolved hydrogen. We establish stability results on the velocity of each phase and on the discrete gradient of the concentration. We show the convergence of a subsequence to a weak solution of the continuous equations as the size of the discretization tends to zero. At our knowledge, this is the first convergence result of finite volume scheme in the case of two component two phase compressible flow in several space dimensions.
Mitrophanov, Alexander Y; Hadley, Tricia J; Groisman, Eduardo A
2010-08-27
Positive feedback loops are regulatory elements that can modulate expression output, kinetics and noise in genetic circuits. Transcriptional regulators participating in such loops are often expressed from two promoters, one constitutive and one autoregulated. Here, we investigate the interplay of promoter strengths and the intensity of the stimulus activating the transcriptional regulator in defining the output of a positively autoregulated genetic circuit. Using a mathematical model of two-component regulatory systems, which are present in all domains of life, we establish that positive feedback strongly affects the steady-state output levels at both low and high levels of stimulus if the constitutive promoter of the regulator is weak. By contrast, the effect of positive feedback is negligible when the constitutive promoter is sufficiently strong, unless the stimulus intensity is very high. Furthermore, we determine that positive feedback can affect both transient and steady state output levels even in the simplest genetic regulatory systems. We tested our modeling predictions by abolishing the positive feedback loop in the two-component regulatory system PhoP/PhoQ of Salmonella enterica, which resulted in diminished induction of PhoP-activated genes. Copyright (c) 2010 Elsevier Ltd. All rights reserved.
Carrano, Charles S.; Rino, Charles L.
2016-06-01
We extend the power law phase screen theory for ionospheric scintillation to account for the case where the refractive index irregularities follow a two-component inverse power law spectrum. The two-component model includes, as special cases, an unmodified power law and a modified power law with spectral break that may assume the role of an outer scale, intermediate break scale, or inner scale. As such, it provides a framework for investigating the effects of a spectral break on the scintillation statistics. Using this spectral model, we solve the fourth moment equation governing intensity variations following propagation through two-dimensional field-aligned irregularities in the ionosphere. A specific normalization is invoked that exploits self-similar properties of the structure to achieve a universal scaling, such that different combinations of perturbation strength, propagation distance, and frequency produce the same results. The numerical algorithm is validated using new theoretical predictions for the behavior of the scintillation index and intensity correlation length under strong scatter conditions. A series of numerical experiments are conducted to investigate the morphologies of the intensity spectrum, scintillation index, and intensity correlation length as functions of the spectral indices and strength of scatter; retrieve phase screen parameters from intensity scintillation observations; explore the relative contributions to the scintillation due to large- and small-scale ionospheric structures; and quantify the conditions under which a general spectral break will influence the scintillation statistics.
Thermal Regulation of Membrane Lipid Fluidity by a Two-Component System in "Bacillus Subtilis"
Bredeston, L. M.; Marciano, D.; Albanesi, D.; De Mendoza, D.; Delfino, J. M.
2011-01-01
This article describes a simple and robust laboratory exercise on the regulation of membrane unsaturated fatty acid composition in bacteria by a decrease in growth temperature. We take advantage of the well characterized Des pathway of "Bacillus subtilis", composed of a [delta]5-desaturase (encoded by the "des" gene) and the canonical…
K. Wei (Katy); M. Moinat (Maxim); T.R. Maarleveld (Timo); F.J. Bruggeman (Frank)
2014-01-01
htmlabstractSignal transduction by prokaryotes almost exclusively relies on two-component systems for sensing and responding to (extracellular) signals. Here, we use stochastic models of two-component systems to better understand the impact of stochasticity on the fidelity and robustness of signal
Lifetime Modeling of Thermal Barrier Coatings
Hille, T.S.
2009-01-01
Thermal barrier coatings (TBCs) are applied in gas turbines to enhance their thermal efficiency by isolating the metallic components from the aggressive hot gas. TBC lifetime is limited by damage processes originating at internal interfaces, which may ultimately lead to delamination and spallation.
Thermal scale modeling of radiation-conduction-convection systems.
Shannon, R. L.
1972-01-01
Investigation of thermal scale modeling applied to radiation-conduction-convection systems with particular emphasis on the spacecraft cabin atmosphere/cabin wall thermal interface. The 'modified material preservation,' 'temperature preservation,' 'scaling compromises,' and 'Nusselt number preservation' scale modeling techniques and their inherent limitations and problem areas are described. The compromised scaling techniques of mass flux preservation and heat transfer coefficient preservation show promise of giving adequate thermal similitude while preserving both gas and temperature in the scale model. The use of these compromised scaling techniques was experimentally demonstrated in tests of full scale and 1/4 scale models. Correlation of test results for free and forced convection under various test conditions shows the effectiveness of these scaling techniques. It is concluded that either mass flux or heat transfer coefficient preservation may result in adequate thermal similitude depending on the system to be modeled. Heat transfer coefficient preservation should give good thermal similitude for manned spacecraft scale modeling applications.
Podar, Mircea
2007-01-01
Two-component signal transduction represents the main mechanism by which bacterial cells interact with their environment. The functional diversity of two-component systems and their relative importance in the different taxonomic groups and ecotypes of bacteria has become evident with the availability of several hundred genomic sequences. The vast majority of bacteria, including many high rank taxonomic units, while being components of complex microbial communities remain uncultured (i.e., have not been isolated or grown in the laboratory). Environmental genomic data from such communities are becoming available, and in addition to its profound impact on microbial ecology it will propel molecular biological disciplines beyond the traditional model organisms. This chapter describes the general approaches used in generating environmental genomic data and how that data can be used to advance the study of two component-systems and signal transduction in general.
Petrini, Pierluigi; Martino, Renato; Ruvolo, Giuseppe
1991-12-01
The management of thermal modeling activities, so as to build up an overall Hermes Thermal Mathematical Model (HTMM), is described. This overall thermal model is developed using ESATAN (ESA Thermal Analysis Network) software. This computer code allows the hierarchical linking of the various 'stand alone' submodels of different compartments of the Spaceplane. In the Hermes program these submodels are built and run independently, and to permit a successful integration some key points must be considered: requirements for submodel/compartment development; interface definition between submodels; boundary conditions for each submodel; consistent thermal parameters database; network change facilities; logic implementation to simulate the mission phases to be analyzed; linking of submodels; requirements for post processing; and result interpretation. These aspects are discussed, underlining the major problems encountered and the solutions adopted.
Thermal Radiation Effects on Thermal Explosion in Polydisperse Fuel Spray-Probabilistic Model
Directory of Open Access Journals (Sweden)
Ophir Navea
2011-06-01
Full Text Available We investigate the effect of thermal radiation on the dynamics of a thermal explosion of polydisperse fuel spray with a complete description of the chemistry via a single-step two-reactant model of general order. The polydisperse spray is modeled using a Probability Density Function (PDF. The thermal radiation energy exchange between the evaporation surface of the fuel droplets and the burning gas is described using the Marshak boundary conditions. An explicit expression of the critical condition for thermal explosion limit is derived analytically and represents a generalization of the critical parameter of the classical Semenov theory. Because we investigated the model in the range where the temperature is very high, the effect of the thermal radiation is significant.
Thermal modeling of a mini rotor-stator system
Dikmen, Emre; Hoogt, van der Peter; Boer, de André; Aarts, Ronald; Jonker, Ben
2009-01-01
In this study the temperature increase and heat dissipation in the air gap of a cylindrical mini rotor stator system has been analyzed. A simple thermal model based on lumped parameter thermal networks has been developed. With this model the temperature dependent air properties for the fluid-rotor i
A Thermal Plume Model for the Martian Convective Boundary Layer
Colaïtis, Arnaud; Hourdin, Frédéric; Rio, Catherine; Forget, François; Millour, Ehouarn
2013-01-01
The Martian Planetary Boundary Layer [PBL] is a crucial component of the Martian climate system. Global Climate Models [GCMs] and Mesoscale Models [MMs] lack the resolution to predict PBL mixing which is therefore parameterized. Here we propose to adapt the "thermal plume" model, recently developed for Earth climate modeling, to Martian GCMs, MMs, and single-column models. The aim of this physically-based parameterization is to represent the effect of organized turbulent structures (updrafts and downdrafts) on the daytime PBL transport, as it is resolved in Large-Eddy Simulations [LESs]. We find that the terrestrial thermal plume model needs to be modified to satisfyingly account for deep turbulent plumes found in the Martian convective PBL. Our Martian thermal plume model qualitatively and quantitatively reproduces the thermal structure of the daytime PBL on Mars: superadiabatic near-surface layer, mixing layer, and overshoot region at PBL top. This model is coupled to surface layer parameterizations taking ...
Multiscale modeling of thermal conductivity of polycrystalline graphene sheets.
Mortazavi, Bohayra; Pötschke, Markus; Cuniberti, Gianaurelio
2014-03-21
We developed a multiscale approach to explore the effective thermal conductivity of polycrystalline graphene sheets. By performing equilibrium molecular dynamics (EMD) simulations, the grain size effect on the thermal conductivity of ultra-fine grained polycrystalline graphene sheets is investigated. Our results reveal that the ultra-fine grained graphene structures have thermal conductivity one order of magnitude smaller than that of pristine graphene. Based on the information provided by the EMD simulations, we constructed finite element models of polycrystalline graphene sheets to probe the thermal conductivity of samples with larger grain sizes. Using the developed multiscale approach, we also investigated the effects of grain size distribution and thermal conductivity of grains on the effective thermal conductivity of polycrystalline graphene. The proposed multiscale approach on the basis of molecular dynamics and finite element methods could be used to evaluate the effective thermal conductivity of polycrystalline graphene and other 2D structures.
Initial data problems for the two-component Camassa-Holm system
Directory of Open Access Journals (Sweden)
Xiaohuan Wang
2014-06-01
Full Text Available This article concerns the study of some properties of the two-component Camassa-Holm system. By constructing two sequences of solutions of the two-component Camassa-Holm system, we prove that the solution map of the Cauchy problem of the two-component Camassa-Holm system is not uniformly continuous in $H^s(\\mathbb{R}$, $s>5/2$.
Directory of Open Access Journals (Sweden)
Ahmed Kadari
2015-11-01
Full Text Available The effect of thermal quenching plays an important role in the thermoluminescence (TL of quartz on which many applications of TL are based. The studies of the stability and kinetics of the 325 °C thermoluminescence peak in quartz are described by Wintle (1975, which show the occurrence of thermal quenching, the decrease in luminescence efficiency with rise in temperature. The thermal quenching of thermoluminescence in quartz was studied experimentally by several authors. The simulations work presented in the literature is based on the single-stage thermal stimulation model of thermoluminescence, in spite of that the mechanisms of this effect remain incomplete. This paper presents a new numerical model for thermal quenching in quartz, using the previously published two-stage thermal stimulation of thermoluminescence model.
Correleation of the SAGE III on ISS Thermal Models in Thermal Desktop
Amundsen, Ruth M.; Davis, Warren T.; Liles, Kaitlin, A. K.; McLeod, Shawn C.
2017-01-01
The Stratospheric Aerosol and Gas Experiment III (SAGE III) instrument is the fifth in a series of instruments developed for monitoring aerosols and gaseous constituents in the stratosphere and troposphere. SAGE III was launched on February 19, 2017 and mounted to the International Space Station (ISS) to begin its three-year mission. A detailed thermal model of the SAGE III payload, which consists of multiple subsystems, has been developed in Thermal Desktop (TD). Correlation of the thermal model is important since the payload will be expected to survive a three-year mission on ISS under varying thermal environments. Three major thermal vacuum (TVAC) tests were completed during the development of the SAGE III Instrument Payload (IP); two subsystem-level tests and a payload-level test. Additionally, a characterization TVAC test was performed in order to verify performance of a system of heater plates that was designed to allow the IP to achieve the required temperatures during payload-level testing; model correlation was performed for this test configuration as well as those including the SAGE III flight hardware. This document presents the methods that were used to correlate the SAGE III models to TVAC at the subsystem and IP level, including the approach for modeling the parts of the payload in the thermal chamber, generating pre-test predictions, and making adjustments to the model to align predictions with temperatures observed during testing. Model correlation quality will be presented and discussed, and lessons learned during the correlation process will be shared.
An electrochemical-thermal coupled overcharge-to-thermal-runaway model for lithium ion battery
Ren, Dongsheng; Feng, Xuning; Lu, Languang; Ouyang, Minggao; Zheng, Siqi; Li, Jianqiu; He, Xiangming
2017-10-01
This paper presents an electrochemical-thermal coupled overcharge-to-thermal-runaway (TR) model to predict the highly interactive electrochemical and thermal behaviors of lithium ion battery under the overcharge conditions. In this model, the battery voltage equals the difference between the cathode potential and the anode potential, whereas the temperature is predicted by modeling the combined heat generations, including joule heat, thermal runaway reactions and internal short circuit. The model can fit well with the adiabatic overcharge tests results at 0.33C, 0.5C and 1C, indicating a good capture of the overcharge-to-TR mechanism. The modeling analysis based on the validated model helps to quantify the heat generation rates of each heat sources during the overcharge-to-TR process. And the two thermal runaway reactions including the electrolyte oxidation reaction and the reaction between deposited lithium and electrolyte are found to contribute most to the heat generations during the overcharge process. Further modeling analysis on the critical parameters is performed to find possible solutions for the overcharge problem of lithium ion battery. The result shows that increasing the oxidation potential of the electrolyte, and increasing the onset temperature of thermal runaway are the two effective ways to improve the overcharge performance of lithium ion battery.
Niu, Ran; Skliar, Mikhail
2012-07-01
In this paper, we develop and validate a method to identify computationally efficient site- and patient-specific models of ultrasound thermal therapies from MR thermal images. The models of the specific absorption rate of the transduced energy and the temperature response of the therapy target are identified in the reduced basis of proper orthogonal decomposition of thermal images, acquired in response to a mild thermal test excitation. The method permits dynamic reidentification of the treatment models during the therapy by recursively utilizing newly acquired images. Such adaptation is particularly important during high-temperature therapies, which are known to substantially and rapidly change tissue properties and blood perfusion. The developed theory was validated for the case of focused ultrasound heating of a tissue phantom. The experimental and computational results indicate that the developed approach produces accurate low-dimensional treatment models despite temporal and spatial noises in MR images and slow image acquisition rate.
Analytical method for yrast line states in the interacting two-component Bose-Einstein condensate
Institute of Scientific and Technical Information of China (English)
解炳昊; 景辉
2002-01-01
The yrast spectrum for the harmonically trapped two-component Bose-Einstein condensate (BEC), omitting thedifference between the two components, has been studied using an analytical method. The energy eigenstates andeigenvalues for L＝0,1,2,3 are given. We illustrate that there are different eigenstate behaviours between the even Land odd L cases for the two-component BEC in two dimensions. Except for symmetric states, there are antisymmetricstates for the permutation of the two components, which cannot reduce to those in a single condensate case when thevalue of L is odd.
Project W-320 thermal hydraulic model benchmarking and baselining
Energy Technology Data Exchange (ETDEWEB)
Sathyanarayana, K.
1998-09-28
Project W-320 will be retrieving waste from Tank 241-C-106 and transferring the waste to Tank 241-AY-102. Waste in both tanks must be maintained below applicable thermal limits during and following the waste transfer. Thermal hydraulic process control models will be used for process control of the thermal limits. This report documents the process control models and presents a benchmarking of the models with data from Tanks 241-C-106 and 241-AY-102. Revision 1 of this report will provide a baselining of the models in preparation for the initiation of sluicing.
Numerical model for thermal parameters in optical materials
Sato, Yoichi; Taira, Takunori
2016-04-01
Thermal parameters of optical materials, such as thermal conductivity, thermal expansion, temperature coefficient of refractive index play a decisive role for the thermal design inside laser cavities. Therefore, numerical value of them with temperature dependence is quite important in order to develop the high intense laser oscillator in which optical materials generate excessive heat across mode volumes both of lasing output and optical pumping. We already proposed a novel model of thermal conductivity in various optical materials. Thermal conductivity is a product of isovolumic specific heat and thermal diffusivity, and independent modeling of these two figures should be required from the viewpoint of a clarification of physical meaning. Our numerical model for thermal conductivity requires one material parameter for specific heat and two parameters for thermal diffusivity in the calculation of each optical material. In this work we report thermal conductivities of various optical materials as Y3Al5O12 (YAG), YVO4 (YVO), GdVO4 (GVO), stoichiometric and congruent LiTaO3, synthetic quartz, YAG ceramics and Y2O3 ceramics. The dependence on Nd3+-doping in laser gain media in YAG, YVO and GVO is also studied. This dependence can be described by only additional three parameters. Temperature dependence of thermal expansion and temperature coefficient of refractive index for YAG, YVO, and GVO: these are also included in this work for convenience. We think our numerical model is quite useful for not only thermal analysis in laser cavities or optical waveguides but also the evaluation of physical properties in various transparent materials.
Thermoset nanocomposites from two-component waterborne polyurethanes and cellulose whiskers.
Wu, Guo-min; Chen, Jian; Huo, Shu-ping; Liu, Gui-feng; Kong, Zhen-wu
2014-05-25
We prepared thermoset nancomposites from biomass-based two-component waterborne polyurethane (2K-WPU) and cellulose namowhiskers (CNWs). Due to the formation of hydrogen bonds, the viscosity of 2K-WPU dispersion was found to be increased with the addition of CNWs. SEM images showed "sea-island structure" corresponding to the microphase separation between CNWs nano-filler and the 2K-WPU matrix. The α-relaxation temperature (Tα) and glass transition temperature (Tg) increased with the increase of CNWs content, which was due to the formation of a rigid CNWs nano-phase acting as crosslinking points in the 2K-WPU matrix. Mechanical properties from tensile test showed Young's modulus and tensile strength of 2K-WPU/CNWs nanocomposites were reinforced by the addition of CNWs. Thermo-stability of 2K-WPU/CNWs nanocomposites decreased slightly with the increase of CNWs content, which could be attributed to the increased thermal conductivity of the material after adding CNWs. Copyright © 2014 Elsevier Ltd. All rights reserved.
Dynamic form factor of two-component plasmas beyond the static local field approximation
Daligault, J
2003-01-01
The spectrum of ion density fluctuations in a strongly coupled plasma is described both within the static G(k, 0) and high-frequency G(k, infinity) local field approximation. By a direct comparison with molecular dynamics data, we find that for large coupling, G(k, 0) is inadequate. Based on this result, we employ the Zwanzig-Mori memory function approach to model the Thomson scattering cross section, i.e. the electron dynamic form factor S sub e sub e (k, omega) of a dense two-component plasma. We show the sensitivity of S sub e sub e (k, omega) to three approximations for G(k, omega).
Histidine phosphotransfer proteins in fungal two-component signal transduction pathways.
Fassler, Jan S; West, Ann H
2013-08-01
The histidine phosphotransfer (HPt) protein Ypd1 is an important participant in the Saccharomyces cerevisiae multistep two-component signal transduction pathway and, unlike the expanded histidine kinase gene family, is encoded by a single gene in nearly all model and pathogenic fungi. Ypd1 is essential for viability in both S. cerevisiae and in Cryptococcus neoformans. These and other aspects of Ypd1 biology, combined with the availability of structural and mutational data in S. cerevisiae, suggest that the essential interactions between Ypd1 and response regulator domains would be a good target for antifungal drug development. The goal of this minireview is to summarize the wealth of data on S. cerevisiae Ypd1 and to consider the potential benefits of conducting related studies in pathogenic fungi.
Cross-talk and specificity in two-component signal transduction pathways.
Agrawal, Ruchi; Sahoo, Bikash Kumar; Saini, Deepak Kumar
2016-05-01
Two-component signaling systems (TCSs) are composed of two proteins, sensor kinases and response regulators, which can cross-talk and integrate information between them by virtue of high-sequence conservation and modular nature, to generate concerted and diversified responses. However, TCSs have been shown to be insulated, to facilitate linear signal transmission and response generation. Here, we discuss various mechanisms that confer specificity or cross-talk among TCSs. The presented models are supported with evidence that indicate the physiological significance of the observed TCS signaling architecture. Overall, we propose that the signaling topology of any TCSs cannot be predicted using obvious sequence or structural rules, as TCS signaling is regulated by multiple factors, including spatial and temporal distribution of the participating proteins.
Chatterjee, Arka; Ghosh, Himadri
2016-01-01
Two component advective flow (TCAF) successfully explains spectral and timing properties of black hole candidates. We study the nature of photon trajectories in the vicinity of a Schwarzschild black hole and incorporate this in predicting images of TCAF with a black hole at the Centre. We also compute the emitted spectra. We employ a Monte-Carlo simulation technique to achieve our goal. For accurate prediction of the image and the spectra, null trajectories are generated without constraining the motion to any specific plane. Red shift, bolometric flux and corresponding temperature have been calculated with appropriate relativistic consideration. The centrifugal barrier dominated boundary layer or CENBOL near the inner region of the disk which acts as the Compton cloud is appropriately modelled as a thick accretion disk in Schwarzschild geometry for the purpose of imaging and computing spectra. The variations of spectra and image with physical parameters such as the accretion rate ($\\dot{m}_d$) and inclination...
Modeling thermally active building components using space mapping
DEFF Research Database (Denmark)
Pedersen, Frank; Weitzmann, Peter; Svendsen, Svend
2005-01-01
simplified models of the components do not always provide useful solutions, since they are not always able to reproduce the correct thermal behavior. The space mapping technique transforms a simplified, but computationally inexpensive model, in order to align it with a detailed model or measurements....... This paper describes the principle of the space mapping technique, and introduces a simple space mapping technique. The technique is applied to a lumped parameter model of a thermo active component, which provides a model of the thermal performance of the component as a function of two design parameters......In order to efficiently implement thermally active building components in new buildings, it is necessary to evaluate the thermal interaction between them and other building components. Applying parameter investigation or numerical optimization methods to a differential-algebraic (DAE) model...
Dynamic validation of the Planck/LFI thermal model
Tomasi, M; Gregorio, A; Colombo, F; Lapolla, M; Terenzi, L; Morgante, G; Bersanelli, M; Butler, R C; Galeotta, S; Mandolesi, N; Maris, M; Mennella, A; Valenziano, L; Zacchei, A; 10.1088/1748-0221/5/01/T01002
2010-01-01
The Low Frequency Instrument (LFI) is an array of cryogenically cooled radiometers on board the Planck satellite, designed to measure the temperature and polarization anisotropies of the cosmic microwave backgrond (CMB) at 30, 44 and 70 GHz. The thermal requirements of the LFI, and in particular the stringent limits to acceptable thermal fluctuations in the 20 K focal plane, are a critical element to achieve the instrument scientific performance. Thermal tests were carried out as part of the on-ground calibration campaign at various stages of instrument integration. In this paper we describe the results and analysis of the tests on the LFI flight model (FM) performed at Thales Laboratories in Milan (Italy) during 2006, with the purpose of experimentally sampling the thermal transfer functions and consequently validating the numerical thermal model describing the dynamic response of the LFI focal plane. This model has been used extensively to assess the ability of LFI to achieve its scientific goals: its valid...
Thermal Model of a Dish Stirling Cavity-Receiver
Rubén Gil; Carlos Monné; Nuria Bernal; Mariano Muñoz; Francisco Moreno
2015-01-01
This paper presents a thermal model for a dish Stirling cavity based on the finite differences method. This model is a theoretical tool to optimize the cavity in terms of thermal efficiency. One of the main outcomes of this work is the evaluation of radiative exchange using the radiosity method; for that purpose, the view factors of all surfaces involved have been accurately calculated. Moreover, this model enables the variation of the cavity and receiver dimensions and the materials to deter...
Energy Technology Data Exchange (ETDEWEB)
Sundberg, Jan; Wrafter, John; Laendell, Maerta (Geo Innova AB (Sweden)); Back, Paer-Erik; Rosen, Lars (Sweco AB (Sweden))
2008-11-15
This report present the results of thermal modelling work for the Forsmark area carried out during modelling stage 2.3. The work complements the main modelling efforts carried out during modelling stage 2.2. A revised spatial statistical description of the rock mass thermal conductivity for rock domain RFM045 is the main result of this work. Thermal modelling of domain RFM045 in Forsmark model stage 2.2 gave lower tail percentiles of thermal conductivity that were considered to be conservatively low due to the way amphibolite, the rock type with the lowest thermal conductivity, was modelled. New and previously available borehole data are used as the basis for revised stochastic geological simulations of domain RFM045. By defining two distinct thermal subdomains, these simulations have succeeded in capturing more of the lithological heterogeneity present. The resulting thermal model for rock domain RFM045 is, therefore, considered to be more realistic and reliable than that presented in model stage 2.2. The main conclusions of modelling efforts in model stage 2.3 are: - Thermal modelling indicates a mean thermal conductivity for domain RFM045 at the 5 m scale of 3.56 W/(mK). This is slightly higher than the value of 3.49 W/(mK) derived in model stage 2.2. - The variance decreases and the lower tail percentiles increase as the scale of observation increases from 1 to 5 m. Best estimates of the 0.1 percentile of thermal conductivity for domain RFM045 are 2.24 W/(mK) for the 1 m scale and 2.36 W/(mK) for the 5 m scale. This can be compared with corresponding values for domain RFM029 of 2.30 W/(mK) for the 1 m scale and 2.87 W/(mK)for the 5 m scale. - The reason for the pronounced lower tail in the thermal conductivity distribution for domain RFM045 is the presence of large bodies of the low-conductive amphibolite. - The modelling results for domain RFM029 presented in model stage 2.2 are still applicable. - As temperature increases, the thermal conductivity decreases
Anglada, Eva; Garmendia, Iñaki
2015-03-01
The design of the thermal control system of space vehicles, needed to maintain the equipment components into their admissible range of temperatures, is usually developed by means of thermal mathematical models. These thermal mathematical models need to be correlated with the equipment real behavior registered during the thermal test campaign, in order to adapt them to the real state of the vehicle "as built". The correlation of this type of mathematical models is a very complex task, usually based on manual procedures, which requires a big effort in time and cost. For this reason, the development of methodologies able to perform this correlation automatically, would be a key aspect in the improvement of the space vehicles thermal control design and validation. The implementation, study and validation of a genetic algorithm able to perform this type of correlation in an automatized way are presented in this paper. The study and validation of the algorithm have been performed based on a simplified model of a real space instrument. The algorithm is able to correlate thermal mathematical models in steady state and transient analyses, and it is also able to perform the simultaneous correlation of several cases, as for example hot and cold cases.
Frequency-domain thermal modelling of power semiconductor devices
DEFF Research Database (Denmark)
Ma, Ke; Blaabjerg, Frede; Andresen, Markus
2015-01-01
to correctly predict the device temperatures, especially when considering the thermal grease and heat sink attached to the power semiconductor devices. In this paper, the frequency-domain approach is applied to the modelling of thermal dynamics for power devices. The limits of the existing RC lump...
Analytical model for non-thermal pressure in galaxy clusters
Shi, Xun; Komatsu, Eiichiro
2014-07-01
Non-thermal pressure in the intracluster gas has been found ubiquitously in numerical simulations, and observed indirectly. In this paper we develop an analytical model for intracluster non-thermal pressure in the virial region of relaxed clusters. We write down and solve a first-order differential equation describing the evolution of non-thermal velocity dispersion. This equation is based on insights gained from observations, numerical simulations, and theory of turbulence. The non-thermal energy is sourced, in a self-similar fashion, by the mass growth of clusters via mergers and accretion, and dissipates with a time-scale determined by the turnover time of the largest turbulence eddies. Our model predicts a radial profile of non-thermal pressure for relaxed clusters. The non-thermal fraction increases with radius, redshift, and cluster mass, in agreement with numerical simulations. The radial dependence is due to a rapid increase of the dissipation time-scale with radii, and the mass and redshift dependence comes from the mass growth history. Combing our model for the non-thermal fraction with the Komatsu-Seljak model for the total pressure, we obtain thermal pressure profiles, and compute the hydrostatic mass bias. We find typically 10 per cent bias for the hydrostatic mass enclosed within r500.
Thermal Modeling and Feedback Requirements for LIFE Neutronic Simulations
Energy Technology Data Exchange (ETDEWEB)
Seifried, J E
2009-07-15
An initial study is performed to determine how temperature considerations affect LIFE neutronic simulations. Among other figures of merit, the isotopic mass accumulation, thermal power, tritium breeding, and criticality are analyzed. Possible fidelities of thermal modeling and degrees of coupling are explored. Lessons learned from switching and modifying nuclear datasets is communicated.
High power solid state retrofit lamp thermal characterization and modeling
Jakovenko, J.; Formánek, J.; Vladimír, J.; Husák, M.; Werkhoven, R.J.
2012-01-01
Thermal and thermo-mechanical modeling and characterization of solid state lightening (SSL) retrofit LED Lamp are presented in this paper. Paramount Importance is to design SSL lamps for reliability, in which thermal and thermo-mechanical aspects are key points. The main goal is to get a precise 3D
Institute of Scientific and Technical Information of China (English)
宣恒农; 左苗
2011-01-01
We present three families of exact matter-wave soliton solutions for an effective one-dimension two- component Bose-Einstein condensates （BECs） with tunable interactions, harmonic potential and gain or loss term. We investigate the dynamics of bright-bright solitons, bright-dark solitons and dark-dark solitons for the time-dependent expulsive harmonic trap potential, periodically modulated harmonic trap potential, and kinklike modulated harmonic trap potential. Through the Feshbach resonance, these dynamics can be realized in experiments by suitable control of time-dependent trap parameters, atomic interactions, and interaction with thermal cloud.
Modeling of Thermal Convection of Liquid TNT for Cookoff
Energy Technology Data Exchange (ETDEWEB)
McCallen, R; Dunn, T; Nichols, A; Reaugh, J; McClelland, M
2003-02-27
The objective is to computationally model thermal convection of liquid TNT in a heated cylindrical container for what are called 'cookoff' experiments. Our goal is to capture the thermal convection coupled to the heat transfer in the surrounding container. We will present computational results that validate the functionality of the model, numerical strategy, and computer code for a model problem with Rayleigh number of O(10{sup 6}). We solve the problem of thermal convection between two parallel plates in this turbulent flow regime and show that the three-dimensional computations are in excellent agreement with experiment.
Note: A simple model for thermal management in solenoids.
McIntosh, E M; Ellis, J
2013-11-01
We describe a model of the dynamical temperature evolution in a solenoid winding. A simple finite element analysis is calibrated by accurately measuring the thermally induced resistance change of the solenoid, thus obviating the need for accurate knowledge of the mean thermal conductivity of the windings. The model predicts quasi thermal runaway for relatively modest current increases from the normal operating conditions. We demonstrate the application of this model to determine the maximum current that can be safely applied to solenoids used for helium spin-echo measurements.
Thermal Entanglement in Lipkin-Meshkov-Glick Model
Institute of Scientific and Technical Information of China (English)
DU Long; ZHANG Wen-Xin; DING Jia-Yan; WANG Guo-Xiang; HOU Jing-Min
2011-01-01
We investigate the thermal entanglement in the Lipkin-Meshkov-Glick (LMG) model which consists of spin-1/2 particles with XXZ-type exchange interactions between any pair of them. The ferromagnetic (FM) and antiferromagnetic (AFM) cases are completely analyzed at both finite temperature and zero temperature. According to the results obtained by accurate numerical calculation, several interesting physic phenomena and characteristics of thermal entanglement in the LMG model are found. Not only do we evaluate the entanglement of the LMG model, but also discover the correlations between macroscopic physical quantities and thermal entanglement.
Viscous and thermal modelling of thermoplastic composites forming process
Guzman, Eduardo; Liang, Biao; Hamila, Nahiene; Boisse, Philippe
2016-10-01
Thermoforming thermoplastic prepregs is a fast manufacturing process. It is suitable for automotive composite parts manufacturing. The simulation of thermoplastic prepreg forming is achieved by alternate thermal and mechanical analyses. The thermal properties are obtained from a mesoscopic analysis and a homogenization procedure. The forming simulation is based on a viscous-hyperelastic approach. The thermal simulations define the coefficients of the mechanical model that depend on the temperature. The forming simulations modify the boundary conditions and the internal geometry of the thermal analyses. The comparison of the simulation with an experimental thermoforming of a part representative of automotive applications shows the efficiency of the approach.
Vitale, Paola; D'Anna, Francesca; Marullo, Salvatore; Noto, Renato
2015-09-07
To identify gel phases able to act as confined reaction media or materials for the removal of organic pollutants, we studied two-component gel phases formed by naphthalenedisulfonate diimidazolium salts in the presence of some organic guests, in 1-propanol solution. Guests differing in π-surface area, bulkiness and electronic properties were taken into account. Soft materials obtained were investigated for their thermal stability, self-repairing ability and morphology. Furthermore, two-component gel phase formation was studied using resonance light scattering (RLS) measurements. Guest release processes from the gel phase were also studied. These processes were monitored as a function of time using both UV-vis and RLS measurements and considering important parameters such as the gelator concentration, the nature of extraction solvent and the extension of contact surface area between solvent and gel phase. Data collected shed light on the properties of the two-component gels and could represent a useful tool to better plan the application of these soft materials.
Two-Component Super AKNS Equations and Their Finite-Dimensional Integrable Super Hamiltonian System
Jing Yu; Jingwei Han
2014-01-01
Starting from a matrix Lie superalgebra, two-component super AKNS system is constructed. By making use of monononlinearization technique of Lax pairs, we find that the obtained two-component super AKNS system is a finite-dimensional integrable super Hamiltonian system. And its Lax representation and $r$ -matrix are also given in this paper.
Relativistic two-component jet evolutions in 2D and 3D
Meliani, Z.; Keppens, R.
2009-01-01
Observations of astrophysical jets and theoretical arguments suggest a transverse stratification with two components induced by intrinsic features of the central engine (accretion disk + black hole). We study two-component jet dynamics for an inner fast low density jet, surrounded by a slower, dense
Two-Component Super AKNS Equations and Their Finite-Dimensional Integrable Super Hamiltonian System
Directory of Open Access Journals (Sweden)
Jing Yu
2014-01-01
Full Text Available Starting from a matrix Lie superalgebra, two-component super AKNS system is constructed. By making use of monononlinearization technique of Lax pairs, we find that the obtained two-component super AKNS system is a finite-dimensional integrable super Hamiltonian system. And its Lax representation and r-matrix are also given in this paper.
Modeling of Thermal Conductivity of Graphite Nanosheet Composites
Lin, Wei; Zhang, Rongwei; Wong, C. P.
2010-03-01
Recent experiments demonstrated a very high thermal conductivity in graphite nanosheet (GNS)/epoxy nanocomposites; however, theoretical analysis is lacking. In this letter, an effective medium model has been used to analyze the effective thermal conductivity of the GNS/polymer nanocomposites and has shown good validity. Strong influences of the aspect ratio and the orientation of the GNS are evident. As expected, interfacial thermal resistance still plays a role in determining the overall thermal transport in the GNS/polymer nanocomposites. In comparison with the interfacial thermal resistance between carbon nanotubes and polymers, the interfacial thermal resistance between GNS and polymers is about one order of magnitude lower, the reason for which is discussed.
Modified Baryonic Dynamics: two-component cosmological simulations with light sterile neutrinos
Energy Technology Data Exchange (ETDEWEB)
Angus, G.W.; Gentile, G. [Department of Physics and Astrophysics, Vrije Universiteit Brussel, Pleinlaan 2, Brussels, 1050 Belgium (Belgium); Diaferio, A. [Dipartimento di Fisica, Università di Torino, Via P. Giuria 1, Torino, I-10125 Italy (Italy); Famaey, B. [Observatoire astronomique de Strasbourg, CNRS UMR 7550, Université de Strasbourg, 11 rue de l' Université, Strasbourg, F-67000 France (France); Heyden, K.J. van der, E-mail: garry.angus@vub.ac.be, E-mail: diaferio@ph.unito.it, E-mail: benoit.famaey@astro.unistra.fr, E-mail: gianfranco.gentile@ugent.be, E-mail: heyden@ast.uct.ac.za [Astrophysics, Cosmology and Gravity Centre, Dept. of Astronomy, University of Cape Town, Private Bag X3, Rondebosch, 7701 South Africa (South Africa)
2014-10-01
In this article we continue to test cosmological models centred on Modified Newtonian Dynamics (MOND) with light sterile neutrinos, which could in principle be a way to solve the fine-tuning problems of the standard model on galaxy scales while preserving successful predictions on larger scales. Due to previous failures of the simple MOND cosmological model, here we test a speculative model where the modified gravitational field is produced only by the baryons and the sterile neutrinos produce a purely Newtonian field (hence Modified Baryonic Dynamics). We use two-component cosmological simulations to separate the baryonic N-body particles from the sterile neutrino ones. The premise is to attenuate the over-production of massive galaxy cluster halos which were prevalent in the original MOND plus light sterile neutrinos scenario. Theoretical issues with such a formulation notwithstanding, the Modified Baryonic Dynamics model fails to produce the correct amplitude for the galaxy cluster mass function for any reasonable value of the primordial power spectrum normalisation.
PATRAN and P/THERMAL applications for thermal modeling. [SP-100 Ground Engineering Station
Energy Technology Data Exchange (ETDEWEB)
Valdiviez, R.; Crea, B.A.
1991-07-01
The standard that has been established over the last decade or so in performing numerical modeling for analysis purposes is to make creation of the computational grid and results presentation less time and effort consuming than the analysis function itself. Software packages known as pre- and post-processors have been developed and made available in various forms and sizes for the engineering analyst's use. These packages reduce the effort and time required of the analyst to perform pre- and post-operations on a given model. PATRAN is one such pre- and post-processing software package. PATRAN provides a large array of capabilities to enable geometric representation and creation of the analysis model. This software package also incorporates interfacing routines which enable a model created in PATRAN to be translated into the input format of many other analysis codes. This paper discusses the use of PATRAN as a pre- and post-processor and the software package P/THERMAL as the analysis code for the steady state and transient thermal analysis of a vacuum vessel. The design objective of the vessel is to duplicate the conditions of outer space and provide containment for a test nuclear reactor designed for space application. This objective creates a challenging thermal analysis effort. The use of P/THERMAL in meeting this challenge is also discussed. P/THERMAL's ability to facilitate and perform thermal analysis is recognized in this analysis task. 2 figs.
Matsumoto, Jin; Masada, Youhei; Asano, Eiji; Shibata, Kazunari
2011-06-01
The nonlinear dynamics of the outflow driven by magnetic explosion on the surface of compact object is investigated through special relativistic magnetohydrodynamic simulations. We adopt, as an initial equilibrium state, a spherical stellar object embedded in the hydrostatic plasma which has a density ρ(r) ~ r-α and is threaded by a dipole magnetic field. The injection of magnetic energy at the surface of compact star breaks the dynamical equilibrium and triggers two-component outflow. At the early evolutionary stage, the magnetic pressure increases rapidly in time around the stellar surface, initiating a magnetically driven outflow. Then it excites a strong forward shock, shock driven outflow. The expansion velocity of the magnetically driven outflow is characterized by the Alfvén velocity on the stellar surface, and follows a simple scaling relation υmag ~ υA1/2. When the initial density profile declines steeply with radius, the strong shock is accelerated self-similarly to relativistic velocity ahead of the magnetically driven component. We find that the evolution of the strong forward shock can be described by a self-similar relation Γsh ~ rsh, where Γsh is the Lorentz factor of the plasma measured at the shock surface rsh. It should be stressed that the pure hydrodynamic process is responsible for the acceleration of the shock driven outflow. Our two-component outflow model, which is the natural outcome of the magnetic explosion, would deepen the understanding of the magnetic active phenomena on various magnetized stellar objects.
One-dimensional models of thermal activation under shear stress
CSIR Research Space (South Africa)
Nabarro, FRN
2003-01-01
Full Text Available The analysis of thermal activation under shear stress in three- and even two-dimensional models presents unresolved problems. The analysis of one-dimensional models presented here may illuminate the study of more realistic models. For the model...
Generation of Granulites Constrained by Thermal Modeling
Depine, G. V.; Andronicos, C. L.; Phipps-Morgan, J.
2006-12-01
The heat source needed to generate granulites facies metamorphism is still an unsolved problem in geology. There is a close spatial relationship between granulite terrains and extensive silicic plutonism, suggesting heat advection by melts is critical to their formation. To investigate the role of heat advection by melt in the generation of granulites we use numerical 1-D models which include the movement of melt from the base of the crust to the middle crust. The model is in part constrained by petrological observations from the Coast Plutonic Complex (CPC) in British Columbia, Canada at ~ 54° N where migmatite and granulite are widespread. The model takes into account time dependent heat conduction and advection of melts generated at the base of the crust. The model starts with a crust of 55 km, consistent with petrologic and geochemical data from the CPC. The lower crust is assumed to be amphibolite in composition, consistent with seismologic and geochemical constraints for the CPC. An initial geothermal gradient estimated from metamorphic P-T-t paths in this region is ~37°C/km, hotter than normal geothermal gradients. The parameters used for the model are a coefficient of thermal conductivity of 2.5 W/m°C, a density for the crust of 2700 kg/m3 and a heat capacity of 1170 J/Kg°C. Using the above starting conditions, a temperature of 1250°C is assumed for the mantle below 55 km, equivalent to placing asthenosphere in contact with the base of the crust to simulate delamination, basaltic underplating and/or asthenospheric exposure by a sudden steepening of slab. This condition at 55 km results in melting the amphibolite in the lower crust. Once a melt fraction of 10% is reached the melt is allowed to migrate to a depth of 13 km, while material at 13 km is displaced downwards to replace the ascending melts. The steady-state profile has a very steep geothermal gradient of more than 50°C/km from the surface to 13 km, consistent with the generation of andalusite
Dynamic validation of the Planck-LFI thermal model
Energy Technology Data Exchange (ETDEWEB)
Tomasi, M; Bersanelli, M; Mennella, A [Universita degli Studi di Milano, Via Celoria 16, 20133 Milano (Italy); Cappellini, B [INAF IASF Milano, Via Bassini, 15, 20133, Milano (Italy); Gregorio, A [University of Trieste, Department of Physics, via Valerio 2, 34127 Trieste (Italy); Colombo, F; Lapolla, M [Thales Alenia Space Italia S.p.A., IUEL - Scientific Instruments, S.S. Padana Superiore 290, 20090 Vimodrone (Mi) (Italy); Terenzi, L; Morgante, G; Butler, R C; Mandolesi, N; Valenziano, L [INAF IASF Bologna, via Gobetti 101, 40129 Bologna (Italy); Galeotta, S; Maris, M; Zacchei, A [LFI-DPC INAF-OATs, via Tiepolo 11, 34131 Trieste (Italy)
2010-01-15
The Low Frequency Instrument (LFI) is an array of cryogenically cooled radiometers on board the Planck satellite, designed to measure the temperature and polarization anisotropies of the cosmic microwave background (CMB) at 30, 44 and 70 GHz. The thermal requirements of the LFI, and in particular the stringent limits to acceptable thermal fluctuations in the 20 K focal plane, are a critical element to achieve the instrument scientific performance. Thermal tests were carried out as part of the on-ground calibration campaign at various stages of instrument integration. In this paper we describe the results and analysis of the tests on the LFI flight model (FM) performed at Thales Laboratories in Milan (Italy) during 2006, with the purpose of experimentally sampling the thermal transfer functions and consequently validating the numerical thermal model describing the dynamic response of the LFI focal plane. This model has been used extensively to assess the ability of LFI to achieve its scientific goals: its validation is therefore extremely important in the context of the Planck mission. Our analysis shows that the measured thermal properties of the instrument show a thermal damping level better than predicted, therefore further reducing the expected systematic effect induced in the LFI maps. We then propose an explanation of the increased damping in terms of non-ideal thermal contacts.
Thermal conductivity modeling of water containing metal oxide nanoparticles
Institute of Scientific and Technical Information of China (English)
Ahmad Azari
2015-01-01
The nano particles have demonstrated great potential to improve the heat transfer characteristics of heat transfer fluids. Possible parameters responsible for this increase were studied. The heat transfer profile in the nanolayer region was combined with other parameters such as volume fraction, particle radius thermal conductivity of the fluid, particle and nanolayer, to formulate a thermal conductivity model. Results predicting the thermal conductivity of nanofluids using the model were compared with experimental results as well as studies by other researchers. The comparison of the results obtained for the CuO/water and TiO2/water nanofluids studied shows that the correlation proposed is in closest proximity in predicting the experimental results for the thermal conductivity of a nanofluid. Also, a parametric study was performed to understand how a number of factors affect the thermal conductivity of nanofluids using the developed correlation.
Thermal performance modeling of NASA s scientific balloons
Franco, H.; Cathey, H.
The flight performance of a scientific balloon is highly dependant on the interaction between the balloon and its environment. The balloon is a thermal vehicle. Modeling a scientific balloon's thermal performance has proven to be a difficult analytical task. Most previous thermal models have attempted these analyses by using either a bulk thermal model approach, or by simplified representations of the balloon. These approaches to date have provided reasonable, but not very accurate results. Improvements have been made in recent years using thermal analysis tools developed for the thermal modeling of spacecraft and other sophisticated heat transfer problems. These tools, which now allow for accurate modeling of highly transmissive materials, have been applied to the thermal analysis of NASA's scientific balloons. A research effort has been started that utilizes the "Thermal Desktop" addition to AUTO CAD. This paper will discuss the development of thermal models for both conventional and Ultra Long Duration super-pressure balloons. This research effort has focused on incremental analysis stages of development to assess the accuracy of the tool and the required model resolution to produce usable data. The first stage balloon thermal analyses started with simple spherical balloon models with a limited number of nodes, and expanded the number of nodes to determine required model resolution. These models were then modified to include additional details such as load tapes. The second stage analyses looked at natural shaped Zero Pressure balloons. Load tapes were then added to these shapes, again with the goal of determining the required modeling accuracy by varying the number of gores. The third stage, following the same steps as the Zero Pressure balloon efforts, was directed at modeling super-pressure pumpkin shaped balloons. The results were then used to develop analysis guidelines and an approach for modeling balloons for both simple first order estimates and detailed
Projection-Based Reduced Order Modeling for Spacecraft Thermal Analysis
Qian, Jing; Wang, Yi; Song, Hongjun; Pant, Kapil; Peabody, Hume; Ku, Jentung; Butler, Charles D.
2015-01-01
This paper presents a mathematically rigorous, subspace projection-based reduced order modeling (ROM) methodology and an integrated framework to automatically generate reduced order models for spacecraft thermal analysis. Two key steps in the reduced order modeling procedure are described: (1) the acquisition of a full-scale spacecraft model in the ordinary differential equation (ODE) and differential algebraic equation (DAE) form to resolve its dynamic thermal behavior; and (2) the ROM to markedly reduce the dimension of the full-scale model. Specifically, proper orthogonal decomposition (POD) in conjunction with discrete empirical interpolation method (DEIM) and trajectory piece-wise linear (TPWL) methods are developed to address the strong nonlinear thermal effects due to coupled conductive and radiative heat transfer in the spacecraft environment. Case studies using NASA-relevant satellite models are undertaken to verify the capability and to assess the computational performance of the ROM technique in terms of speed-up and error relative to the full-scale model. ROM exhibits excellent agreement in spatiotemporal thermal profiles (<0.5% relative error in pertinent time scales) along with salient computational acceleration (up to two orders of magnitude speed-up) over the full-scale analysis. These findings establish the feasibility of ROM to perform rational and computationally affordable thermal analysis, develop reliable thermal control strategies for spacecraft, and greatly reduce the development cycle times and costs.
Thermal Model Predictions of Advanced Stirling Radioisotope Generator Performance
Wang, Xiao-Yen J.; Fabanich, William Anthony; Schmitz, Paul C.
2014-01-01
This presentation describes the capabilities of three-dimensional thermal power model of advanced stirling radioisotope generator (ASRG). The performance of the ASRG is presented for different scenario, such as Venus flyby with or without the auxiliary cooling system.
Coupling of the Models of Human Physiology and Thermal Comfort
Pokorny, J.; Jicha, M.
2013-04-01
A coupled model of human physiology and thermal comfort was developed in Dymola/Modelica. A coupling combines a modified Tanabe model of human physiology and thermal comfort model developed by Zhang. The Coupled model allows predicting the thermal sensation and comfort of both local and overall from local boundary conditions representing ambient and personal factors. The aim of this study was to compare prediction of the Coupled model with the Fiala model prediction and experimental data. Validation data were taken from the literature, mainly from the validation manual of software Theseus-FE [1]. In the paper validation of the model for very light physical activities (1 met) indoor environment with temperatures from 12 °C up to 48 °C is presented. The Coupled model predicts mean skin temperature for cold, neutral and warm environment well. However prediction of core temperature in cold environment is inaccurate and very affected by ambient temperature. Evaluation of thermal comfort in warm environment is supplemented by skin wettedness prediction. The Coupled model is designed for non-uniform and transient environmental conditions; it is also suitable simulation of thermal comfort in vehicles cabins. The usage of the model is limited for very light physical activities up to 1.2 met only.
Thermal ripples in model molybdenum disulfide monolayers
Energy Technology Data Exchange (ETDEWEB)
Remsing, Richard C.; Klein, Michael L. [Institute for Computational Molecular Science, Center for the Computational, Design of Functional Layered Materials, and Department of Chemistry, Temple University, 1925 N. 12th St., 19122, Philadelphia, PA (United States); Waghmare, Umesh V. [Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, 560 064, Jakkur, Bangalore (India)
2017-01-15
Molybdenum disulfide (MoS{sub 2}) monolayers have the potential to revolutionize nanotechnology. To reach this potential, it will be necessary to understand the behavior of this two-dimensional (2D) material on large length scales and under thermal conditions. Herein, we use molecular dynamics (MD) simulations to investigate the nature of the rippling induced by thermal fluctuations in monolayers of the 2H and 1T phases of MoS{sub 2}. The 1T phase is found to be more rigid than the 2H phase. Both monolayer phases are predicted to follow long wavelength scaling behavior typical of systems with anharmonic coupling between vibrational modes as predicted by classic theories of membrane-like systems. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
The Lattice and Thermal Radiation Conductivity of Thermal Barrier Coatings: Models and Experiments
Zhu, Dongming; Spuckler, Charles M.
2010-01-01
The lattice and radiation conductivity of ZrO2-Y2O3 thermal barrier coatings was evaluated using a laser heat flux approach. A diffusion model has been established to correlate the coating apparent thermal conductivity to the lattice and radiation conductivity. The radiation conductivity component can be expressed as a function of temperature, coating material scattering, and absorption properties. High temperature scattering and absorption of the coating systems can be also derived based on the testing results using the modeling approach. A comparison has been made for the gray and nongray coating models in the plasma-sprayed thermal barrier coatings. The model prediction is found to have a good agreement with experimental observations.
Aeroheating Mapping to Thermal Model for Autonomous Aerobraking Capability
Amundsen, Ruth M.
2010-01-01
Thermal modeling has been performed to evaluate the potential for autonomous aerobraking of a spacecraft in the atmosphere of a planet. As part of this modeling, the aeroheating flux during aerobraking must be applied to the spacecraft solar arrays to evaluate their thermal response. On the Mars Reconnaissance Orbiter (MRO) mission, this was done via two separate thermal models and an extensive suite of mapping scripts. That method has been revised, and the thermal analysis of an aerobraking pass can now be accomplished via a single thermal model, using a new capability in the Thermal Desktop software. This capability, Boundary Condition Mapper, has the ability to input heating flux files that vary with time, position on the solar array, and with the skin temperature. A recently added feature to the Boundary Condition Mapper is that this module can also utilize files that describe the variation of aeroheating over the surface with atmospheric density (rather than time); this is the format of the MRO aeroheating files. This capability has allowed a huge streamlining of the MRO thermal process, simplifying the procedure for importing new aeroheating files and trajectory information. The new process, as well as the quantified time savings, is described.
Thermal properties. Site descriptive modelling Forsmark - stage 2.2
Energy Technology Data Exchange (ETDEWEB)
Back, Paer-Erik; Wrafter, John; Sundberg, Jan [Geo Innova AB (Sweden); Rosen, L ars [Sweco Viak AB (Sweden)
2007-09-15
The lithological data acquired from boreholes and mapping of the rock surface need to be reclassified into thermal rock classes, TRCs. The main reason is to simplify the simulations. The lithological data are used to construct models of the transition between different TRCs, thus describing the spatial statistical structure of each TRC. The result is a set of transition probability models that are used in the simulation of TRCs. The intermediate result of this first stochastic simulation is a number of realisations of the geology, each one equally probable. Based on the thermal data, a spatial statistical thermal model is constructed for each TRC. It consists of a statistical distribution and a variogram for each TRC. These are used in the stochastic simulation of thermal conductivity and the result is a number of equally probable realisations of thermal conductivity for the domain. In the next step, the realisations of TRCs (lithology) and thermal conductivity are merged, i.e. each realisation of geology is filled with simulated thermal conductivity values. The result is a set of realisations of thermal conductivity that considers both the difference in thermal properties between different TRCs, and the variability within each TRC. If the result is desired in a scale different from the simulation scale, i.e. the canister scale, upscaling of the realisations can be performed. The result is a set of equally probable realisations of thermal properties. The presented methodology was applied to rock domain RFM029 and RFM045. The main results are sets of realisations of thermal properties that can be used for further processing, most importantly for statistical analysis and numerical temperature simulations for the design of repository layout (distances between deposition holes). The main conclusions of the thermal modelling are: The choice of scale has a profound influence on the distribution of thermal conductivity values. The variance decreases and the lower tail
Measurement and model on thermal properties of sintered diamond composites
Energy Technology Data Exchange (ETDEWEB)
Moussa, Tala, E-mail: Tala.moussa@univ-nantes.fr [Laboratoire de Thermocinetique UMR CNRS 6607, Polytech, Universite de nantes, BP 50609, rue Christian Pauc, 44306 Nantes (France); Garnier, Bertrand; Peerhossaini, Hassan [Laboratoire de Thermocinetique UMR CNRS 6607, Polytech, Universite de nantes, BP 50609, rue Christian Pauc, 44306 Nantes (France)
2013-02-25
Highlights: Black-Right-Pointing-Pointer Thermal properties of sintered diamond used for grinding is studied. Black-Right-Pointing-Pointer Flash method with infrared temperature measurement is used to investigate. Black-Right-Pointing-Pointer Thermal conductivity increases with the amount of diamond. Black-Right-Pointing-Pointer It is very sensitive to binder conductivity. Black-Right-Pointing-Pointer Results agree with models assuming imperfect contact between matrix and particles. - Abstract: A prelude to the thermal management of grinding processes is measurement of the thermal properties of working materials. Indeed, tool materials must be chosen not only for their mechanical properties (abrasion performance, lifetime Horizontal-Ellipsis ) but also for thermal concerns (thermal conductivity) for efficient cooling that avoids excessive temperatures in the tool and workpiece. Sintered diamond is currently used for grinding tools since it yields higher performances and longer lifetimes than conventional materials (mineral or silicon carbide abrasives), but its thermal properties are not yet well known. Here the thermal conductivity, heat capacity and density of sintered diamond are measured as functions of the diamond content in composites and for two types of metallic binders: hard tungsten-based and soft cobalt-based binders. The measurement technique for thermal conductivity is derived from the flash method. After pulse heating, the temperature of the rear of the sample is measured with a noncontact method (infrared camera). A parameter estimation method associated with a three-layer nonstationary thermal model is used to obtain sample thermal conductivity, heat transfer coefficient and absorbed energy. With the hard metallic binder, the thermal conductivity of sintered diamond increased by up to 64% for a diamond content increasing from 0 to 25%. The increase is much less for the soft binder: 35% for diamond volumes up to 25%. In addition, experimental data
Modeling thermal effects in braking systems of railway vehicles
Directory of Open Access Journals (Sweden)
Milošević Miloš S.
2012-01-01
Full Text Available The modeling of thermal effects has become increasingly important in product design in different transport means, road vehicles, airplanes, railway vehicles, and so forth. The thermal analysis is a very important stage in the study of braking systems, especially of railway vehicles, where it is necessary to brake huge masses, because the thermal load of a braked railway wheel prevails compared to other types of loads. In the braking phase, kinetic energy transforms into thermal energy resulting in intense heating and high temperature states of railway wheels. Thus induced thermal loads determine thermomechanical behavior of the structure of railway wheels. In cases of thermal overloads, which mainly occur as a result of long-term braking on down-grade railroads, the generation of stresses and deformations occurs, whose consequences are the appearance of cracks on the rim of a wheel and the final total wheel defect. The importance to precisely determine the temperature distribution caused by the transfer process of the heat generated during braking due to the friction on contact surfaces of the braking system makes it a challenging research task. Therefore, the thermal analysis of a block-braked solid railway wheel of a 444 class locomotive of the national railway operator Serbian Railways is processed in detail in this paper, using analytical and numerical modeling of thermal effects during long-term braking for maintaining a constant speed on a down-grade railroad.
Preparation and frictional investigation of the two-components silanes deposited on alumina surface
Energy Technology Data Exchange (ETDEWEB)
Kośla, K.; Grobelny, J.; Cichomski, M., E-mail: mcichom@uni.lodz.pl
2014-09-30
Highlights: • The two-component silane films on the alumina surface were obtained by a combination of soft lithography and vapor phase deposition method. • The effectiveness of modification procedure was monitored by AFM topography images. • By using gas phase deposition method succeeded in obtaining a good reproduction of pattern. • Silane films with low surface free energy and coefficient of friction values were obtained. • The frictional performance in milli-Newton load range of one- and two-component films was investigated by microtribometry. - Abstract: Functionalization and pattering technique that permits two-component pattern-specific modification of alumina surface with silanes molecules are reported. The method relies on a two-component molecular system that simultaneously decreases coefficient of friction of the alumina surface and provides uniform chemical functionality suitable for further elaboration. Pattern/two-component modification is achieved via gas-phase deposition of the silanes using polydimethylsiloxane stamp. The frictional behaviors of the two-component films of the silane molecules with different chain length covalently absorbed on alumina surfaces, were characterized by the ball-disk (microtribometer) tester. The surfaces of the substrate modified by two-component molecular films were examined by atomic force microscopy (AFM). The measured tribological results showed that the mixing of the fluoroalkylsilane and alkylsilane enhance the lubrication and decrease the friction compared to the one-component thin films.
Energy Technology Data Exchange (ETDEWEB)
Pannala, S; D' Azevedo, E; Zacharia, T
2002-02-26
The goal of the radiation modeling effort was to develop and implement a radiation algorithm that is fast and accurate for the underhood environment. As part of this CRADA, a net-radiation model was chosen to simulate radiative heat transfer in an underhood of a car. The assumptions (diffuse-gray and uniform radiative properties in each element) reduce the problem tremendously and all the view factors for radiation thermal calculations can be calculated once and for all at the beginning of the simulation. The cost for online integration of heat exchanges due to radiation is found to be less than 15% of the baseline CHAD code and thus very manageable. The off-line view factor calculation is constructed to be very modular and has been completely integrated to read CHAD grid files and the output from this code can be read into the latest version of CHAD. Further integration has to be performed to accomplish the same with STAR-CD. The main outcome of this effort is to obtain a highly scalable and portable simulation capability to model view factors for underhood environment (for e.g. a view factor calculation which took 14 hours on a single processor only took 14 minutes on 64 processors). The code has also been validated using a simple test case where analytical solutions are available. This simulation capability gives underhood designers in the automotive companies the ability to account for thermal radiation - which usually is critical in the underhood environment and also turns out to be one of the most computationally expensive components of underhood simulations. This report starts off with the original work plan as elucidated in the proposal in section B. This is followed by Technical work plan to accomplish the goals of the project in section C. In section D, background to the current work is provided with references to the previous efforts this project leverages on. The results are discussed in section 1E. This report ends with conclusions and future scope of
Methods of producing epoxides from alkenes using a two-component catalyst system
Kung, Mayfair C.; Kung, Harold H.; Jiang, Jian
2013-07-09
Methods for the epoxidation of alkenes are provided. The methods include the steps of exposing the alkene to a two-component catalyst system in an aqueous solution in the presence of carbon monoxide and molecular oxygen under conditions in which the alkene is epoxidized. The two-component catalyst system comprises a first catalyst that generates peroxides or peroxy intermediates during oxidation of CO with molecular oxygen and a second catalyst that catalyzes the epoxidation of the alkene using the peroxides or peroxy intermediates. A catalyst system composed of particles of suspended gold and titanium silicalite is one example of a suitable two-component catalyst system.
Two-component generalizations of the periodic Camassa-Holm and Degasperis-Procesi equations
Escher, Joachim; Lenells, Jonatan
2010-01-01
We use geometric methods to study two natural two-component generalizations of the periodic Camassa-Holm and Degasperis-Procesi equations. We show that these generalizations can be regarded as geodesic equations on the semidirect product of the diffeomorphism group of the circle $\\Diff(S^1)$ with some space of sufficiently smooth functions on the circle. Our goals are to understand the geometric properties of these two-component systems and to prove local well-posedness in various function spaces. Furthermore, we perform some explicit curvature calculations for the two-component Camassa-Holm equation, giving explicit examples of large subspaces of positive curvature.
Evolution and phyletic distribution of two-component signal transduction systems.
Wuichet, Kristin; Cantwell, Brian J; Zhulin, Igor B
2010-04-01
Two-component signal transduction systems are abundant in prokaryotes. They enable cells to adjust multiple cellular functions in response to changing environmental conditions. These systems are also found, although in much smaller numbers, in lower eukaryotes and plants, where they appear to control a few very specific functions. Two-component systems have evolved in Bacteria from much simpler one-component systems bringing about the benefit of extracellular versus intracellular sensing. We review reports establishing the origins of two-component systems and documenting their occurrence in major lineages of Life. Copyright 2010 Elsevier Ltd. All rights reserved.
Two-Component Wadati-Konno-Ichikawa Equation and Its Symmetry Reductions
Institute of Scientific and Technical Information of China (English)
QU Chang-Zheng; YAO Ruo-Xia; LI Zhi-Bin
2004-01-01
@@ It is shown that two-component Wadati-Konno-Ichikawa (WKI) equation, i.e. a generalization of the well-known WKI equation, is obtained from the motion of space curves in Euclidean geometry, and it is exactly a system for the graph of the curves when the curve motion is governed by the two-component modified Korteweg-de Vries flow. Group-invariant solutions of the two-component WKI equation which corresponds to an optimal system of its Lie point symmetry groups are obtained, and its similarity reductions to systems of ordinary differential equations are also given.
Thermal structure of the lithosphere: a petrologic model.
Macgregor, I D; Basu, A R
1974-09-20
A preliminary evaluation of the thermal history of the upper mantle as determined by petrologic techniques indicates a general correspondence with theoretically derived models. The petrologic data supply direct information which may be used as an independent calibration of calculated models, serve as a base for evaluating the assumptions of the theoretical approach, and allow more careful selection of the variables describing mantle thermal properties and processes. Like the theoretical counterpart, the petrological approach indicates that the lithosphere is dominated by two thermal regimes: first, there is a continental regime which cools at rates of the order of 10(9) years and represents the longterm cooling of the earth. Secondly, superimposed on the continental evolution is the thermal event associated with the formation of an oceanic basin, and which may be thought of as a 10(8) year convective perturbation on the continental cycle. Of special interest is petrologic evidence for a sudden steepening of the thermal gradients across the lithosphere-asthenosphere boundary not seen in the theoretical models. The unexpected change of slope points to the need for a critical reevaluation of the thermal processes and properties extant in the asthenosphere. The potential of the petrologic contribution has yet to be fully realized. For a start, this article points to an important body of independent evidence critical to our understanding of the earth's thermal history.
Evaluation of the Thermodynamic Models for the Thermal Diffusion Factor
DEFF Research Database (Denmark)
Gonzalez-Bagnoli, Mariana G.; Shapiro, Alexander; Stenby, Erling Halfdan
2003-01-01
Over the years, several thermodynamic models for the thermal diffusion factors for binary mixtures have been proposed. The goal of this paper is to test some of these models in combination with different equations of state. We tested the following models: those proposed by Rutherford and Drickame...
Hierarchical set of models to estimate soil thermal diffusivity
Arkhangelskaya, Tatiana; Lukyashchenko, Ksenia
2016-04-01
Soil thermal properties significantly affect the land-atmosphere heat exchange rates. Intra-soil heat fluxes depend both on temperature gradients and soil thermal conductivity. Soil temperature changes due to energy fluxes are determined by soil specific heat. Thermal diffusivity is equal to thermal conductivity divided by volumetric specific heat and reflects both the soil ability to transfer heat and its ability to change temperature when heat is supplied or withdrawn. The higher soil thermal diffusivity is, the thicker is the soil/ground layer in which diurnal and seasonal temperature fluctuations are registered and the smaller are the temperature fluctuations at the soil surface. Thermal diffusivity vs. moisture dependencies for loams, sands and clays of the East European Plain were obtained using the unsteady-state method. Thermal diffusivity of different soils differed greatly, and for a given soil it could vary by 2, 3 or even 5 times depending on soil moisture. The shapes of thermal diffusivity vs. moisture dependencies were different: peak curves were typical for sandy soils and sigmoid curves were typical for loamy and especially for compacted soils. The lowest thermal diffusivities and the smallest range of their variability with soil moisture were obtained for clays with high humus content. Hierarchical set of models will be presented, allowing an estimate of soil thermal diffusivity from available data on soil texture, moisture, bulk density and organic carbon. When developing these models the first step was to parameterize the experimental thermal diffusivity vs. moisture dependencies with a 4-parameter function; the next step was to obtain regression formulas to estimate the function parameters from available data on basic soil properties; the last step was to evaluate the accuracy of suggested models using independent data on soil thermal diffusivity. The simplest models were based on soil bulk density and organic carbon data and provided different
Gupta, Mohit; Kumara, Chamara; Nylén, Per
2017-08-01
Suspension plasma spraying (SPS) has been shown as a promising process to produce porous columnar strain tolerant coatings for thermal barrier coatings (TBCs) in gas turbine engines. However, the highly porous structure is vulnerable to crack propagation, especially near the topcoat-bondcoat interface where high stresses are generated due to thermal cycling. A topcoat layer with high toughness near the topcoat-bondcoat interface could be beneficial to enhance thermal cyclic lifetime of SPS TBCs. In this work, a bilayer coating system consisting of first a dense layer near the topcoat-bondcoat interface followed by a porous columnar layer was fabricated by SPS using Yttria-stabilised zirconia suspension. The objective of this work was to investigate if the bilayer topcoat architecture could enhance the thermal cyclic lifetime of SPS TBCs through experiments and to understand the effect of the column gaps/vertical cracks and the dense layer on the generated stresses in the TBC during thermal cyclic loading through finite element modeling. The experimental results show that the bilayer TBC had significantly higher lifetime than the single-layer TBC. The modeling results show that the dense layer and vertical cracks are beneficial as they reduce the thermally induced stresses which thus increase the lifetime.
Ablation Modeling of Ares-I Upper State Thermal Protection System Using Thermal Desktop
Sharp, John R.; Page, Arthur T.
2007-01-01
The thermal protection system (TPS) for the Ares-I Upper Stage will be based on Space Transportation System External Tank (ET) and Solid Rocket Booster (SRB) heritage materials. These TPS materials were qualified via hot gas testing that simulated ascent and re-entry aerothermodynamic convective heating environments. From this data, the recession rates due to ablation were characterized and used in thermal modeling for sizing the thickness required to maintain structural substrate temperatures. At Marshall Space Flight Center (MSFC), the in-house code ABL is currently used to predict TPS ablation and substrate temperatures as a FORTRAN application integrated within SINDA/G. This paper describes a comparison of the new ablation utility in Thermal Desktop and SINDA/FLUINT with the heritage ABL code and empirical test data which serves as the validation of the Thermal Desktop software for use on the design of the Ares-I Upper Stage project.
Multiscale Modeling of Thermal Conductivity of Polymer/Carbon Nanocomposites
Clancy, Thomas C.; Frankland, Sarah-Jane V.; Hinkley, Jeffrey A.; Gates, Thomas S.
2010-01-01
Molecular dynamics simulation was used to estimate the interfacial thermal (Kapitza) resistance between nanoparticles and amorphous and crystalline polymer matrices. Bulk thermal conductivities of the nanocomposites were then estimated using an established effective medium approach. To study functionalization, oligomeric ethylene-vinyl alcohol copolymers were chemically bonded to a single wall carbon nanotube. The results, in a poly(ethylene-vinyl acetate) matrix, are similar to those obtained previously for grafted linear hydrocarbon chains. To study the effect of noncovalent functionalization, two types of polyethylene matrices. -- aligned (extended-chain crystalline) vs. amorphous (random coils) were modeled. Both matrices produced the same interfacial thermal resistance values. Finally, functionalization of edges and faces of plate-like graphite nanoparticles was found to be only modestly effective in reducing the interfacial thermal resistance and improving the composite thermal conductivity
Thermal Error Modelling of the Spindle Using Neurofuzzy Systems
Jingan Feng; Xiaoqi Tang; Yanlei Li; Bao Song
2016-01-01
This paper proposes a new combined model to predict the spindle deformation, which combines the grey models and the ANFIS (adaptive neurofuzzy inference system) model. The grey models are used to preprocess the original data, and the ANFIS model is used to adjust the combined model. The outputs of the grey models are used as the inputs of the ANFIS model to train the model. To evaluate the performance of the combined model, an experiment is implemented. Three Pt100 thermal resistances are use...
Modeling the population lens effect in thermal lens spectrometry.
Silva, J R; Malacarne, L C; Baesso, M L; Lima, S M; Andrade, L H C; Jacinto, C; Hehlen, M P; Astrath, N G C
2013-02-15
We report a theoretical model and experimental results for laser-induced lensing in solids. The model distinguishes and quantifies the contributions from population and thermal effects. Laser-induced lensing in ytterbium-doped fluorozirconate glass ZBLAN:Yb(3+) is measured, and the thermal and optical properties obtained from analyzing the data with the proposed model agree well with published values. Photothermal techniques are used extensively for the investigation of laser and laser-cooling materials, and the model developed here enables the interpretation of convoluted laser-induced lensing signals that have contributions from different sources.
A general thermal model of machine tool spindle
Directory of Open Access Journals (Sweden)
Yanfang Dong
2017-01-01
Full Text Available As the core component of machine tool, the thermal characteristics of the spindle have a significant influence on machine tool running status. Lack of an accurate model of the spindle system, particularly the model of load–deformation coefficient between the bearing rolling elements and rings, severely limits the thermal error analytic precision of the spindle. In this article, bearing internal loads, especially the function relationships between the principal curvature difference F(ρ and auxiliary parameter nδ, semi-major axis a, and semi-minor axis b, have been determined; furthermore, high-precision heat generation combining the heat sinks in the spindle system is calculated; finally, an accurate thermal model of the spindle was established. Moreover, a conventional spindle with embedded fiber Bragg grating temperature sensors has been developed. By comparing the experiment results with simulation, it indicates that the model has good accuracy, which verifies the reliability of the modeling process.
Virtual Sensor for Calibration of Thermal Models of Machine Tools
Directory of Open Access Journals (Sweden)
Alexander Dementjev
2014-01-01
strictly depends on the accuracy of these machines, but they are prone to deformation caused by their own heat. The deformation needs to be compensated in order to assure accurate production. So an adequate model of the high-dimensional thermal deformation process must be created and parameters of this model must be evaluated. Unfortunately, such parameters are often unknown and cannot be calculated a priori. Parameter identification during real experiments is not an option for these models because of its high engineering and machine time effort. The installation of additional sensors to measure these parameters directly is uneconomical. Instead, an effective calibration of thermal models can be reached by combining real and virtual measurements on a machine tool during its real operation, without additional sensors installation. In this paper, a new approach for thermal model calibration is presented. The expected results are very promising and can be recommended as an effective solution for this class of problems.
Energy Technology Data Exchange (ETDEWEB)
Back, Paer-Erik; Sundberg, Jan [Geo Innova AB (Sweden)
2007-09-15
This report presents a strategy for describing, predicting and visualising the thermal aspects of the site descriptive model. The strategy is an updated version of an earlier strategy applied in all SDM versions during the initial site investigation phase at the Forsmark and Oskarshamn areas. The previous methodology for thermal modelling did not take the spatial correlation fully into account during simulation. The result was that the variability of thermal conductivity in the rock mass was not sufficiently well described. Experience from earlier thermal SDMs indicated that development of the methodology was required in order describe the spatial distribution of thermal conductivity in the rock mass in a sufficiently reliable way, taking both variability within rock types and between rock types into account. A good description of the thermal conductivity distribution is especially important for the lower tail. This tail is important for the design of a repository because it affects the canister spacing. The presented approach is developed to be used for final SDM regarding thermal properties, primarily thermal conductivity. Specific objectives for the strategy of thermal stochastic modelling are: Description: statistical description of the thermal conductivity of a rock domain. Prediction: prediction of thermal conductivity in a specific rock volume. Visualisation: visualisation of the spatial distribution of thermal conductivity. The thermal site descriptive model should include the temperature distribution and thermal properties of the rock mass. The temperature is the result of the thermal processes in the repository area. Determination of thermal transport properties can be made using different methods, such as laboratory investigations, field measurements, modelling from mineralogical composition and distribution, modelling from density logging and modelling from temperature logging. The different types of data represent different scales, which has to be
Compound fuzzy model for thermal performance of refrigeration compressors
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
The fuzzy method is introduced to the calculation of thermal performance of refrigeration compressors. A compound model combining classical thermodynamic theory and fuzzy theory is presented and compared with a simple fuzzy model without classical thermodynamic fundamentals. Case study of refrigeration compressors shows that the compound fuzzy model and the simple fuzzy model are both more efficient than the classical thermodynamic method. However, the compound fuzzy model is of better precision and adaptability.
Thermal distortion modeling of mirrors based on experimental data.
Gierloff, J J
1981-04-01
Mirrors are modeled to match test results from the Thermal Distortion Test Facility (TDTF) at Kirtland AFB, Albuquerque, N.M. The model allows distortions resulting from realistic beam profiles to be accurately calculated from a closed-form five-parameter equation. The basic modeling concepts as well as the model's capabilities are discussed. A comparison of model distortion predictions with observed distortions resulting from a high-energy laser beam is made.
Scale and Contour: Two Components of a Theory of Memory for Melodies.
Dowling, W. Jay
1978-01-01
The author concentrates on two components of memory which contribute to the reproduction and recognition of melodies, namely, melodic contour and musical scale. A new experiment is reported that shows the interdependence of both components. (Author/RK)
Laser controlling chaotic region of a two-component Bose-Einstein condensate
Institute of Scientific and Technical Information of China (English)
Boli Xia; Wenhua Hai
2005-01-01
@@ For a weakly and periodically driven two-component Bose-Einstein condensate (BEC) the Melnikov chaotic solution and boundedness conditions are derived from a direct perturbation theory that leads to the chaotic regions in the parameter space.
Two component injection moulding: an interface quality and bond strength dilemma
DEFF Research Database (Denmark)
Islam, Mohammad Aminul; Hansen, Hans Nørgaard; Tang, Peter Torben
2008-01-01
Two component injection moulding is a special branch of injection moulding where two different polymers are combined in to a single part to exploit the different material properties in the final product. Considering the technical and economical importance of the process, this paper investigates...... on quality parameters of the two component parts. Most engineering applications of two component injection moulding calls for high bond strength between the two polymers, on the other hand a sharp and well-defined interface between the two polymers are required for applications like selective metallization...... conditions for a sharp and well-defined interface are exactly the opposite of what is congenial for higher bond strength. So in the production of two component injection moulded parts, there is a compromise to make between the interface quality and the bond strength of the two polymers. Also the injection...
ZHAO, Haiyan; Tang, Liang
2009-01-01
The multidomain cytoplasmic portion of the histidine protein kinase from an essential two-component signal transduction system has been crystallized and X-ray data have been collected to 2.8 Å resolution.
Energy Technology Data Exchange (ETDEWEB)
Lu Xiaoshu
2002-07-01
The objective of this thesis is to firstly develop a mathematical model for predicting heat and moisture transfer in buildings exposed to outdoor climatic conditions presented as temperature, relative humidity, solar radiation and wind velocity. Secondly, the heat and moisture transfer model is used to theoretically study the possibilities of controlling indoor thermal and moisture levels into an allowable range by means of heating indoor air and ventilating outdoor air. Starting from an extensive literature, it is indicated that less attention has been devoted to the topic that is similar to this thesis work. The reviewed literature has been classified into different categories in a consistent and systematic way. In modelling heat and moisture transfer in a building, the building structure is split into two components: building indoor air and building envelopes, most of which are porous media. The heat and moisture transfer equations are based on the fundamental thermodynamic relations. Darcy's law, Fick's law and Fourier's law are used in describing the transfer equations. The resultant nonlinear system of partial differential equations is discretised by using the finite element method or the finite difference method. The time marching scheme, Crank-Nicolson scheme, is adopted to advance the solution in time. The final solution provides transient distributions of thermal, moisture content and gaseous pressure for the envelopes as well as the transient thermal and moisture content for indoor air. The model program, named as HMTB, is validated with the real test houses. HMTB has a highly flexibility: It has been used to simulate the multiphase drying process of a porous medium. It has been adopted to predict transient thermal and moisture contents for buildings, transient indoor moisture generation rates and condensation potential on the wall surfaces. In studying the applications of indoor thermal and moisture control, HMTB has been applied to
Mathematical Models of IABG Thermal-Vacuum Facilities
Doring, Daniel; Ulfers, Hendrik
2014-06-01
IABG in Ottobrunn, Germany, operates thermal-vacuum facilities of different sizes and complexities as a service for space-testing of satellites and components. One aspect of these tests is the qualification of the thermal control system that keeps all onboard components within their save operating temperature band. As not all possible operation / mission states can be simulated within a sensible test time, usually a subset of important and extreme states is tested at TV facilities to validate the thermal model of the satellite, which is then used to model all other possible mission states. With advances in the precision of customer thermal models, simple assumptions of the test environment (e.g. everything black & cold, one solar constant of light from this side) are no longer sufficient, as real space simulation chambers do deviate from this ideal. For example the mechanical adapters which support the spacecraft are usually not actively cooled. To enable IABG to provide a model that is sufficiently detailed and realistic for current system tests, Munich engineering company CASE developed ESATAN models for the two larger chambers. CASE has many years of experience in thermal analysis for space-flight systems and ESATAN. The two models represent the rather simple (and therefore very homogeneous) 3m-TVA and the extremely complex space simulation test facility and its solar simulator. The cooperation of IABG and CASE built up extensive knowledge of the facilities thermal behaviour. This is the key to optimally support customers with their test campaigns in the future. The ESARAD part of the models contains all relevant information with regard to geometry (CAD data), surface properties (optical measurements) and solar irradiation for the sun simulator. The temperature of the actively cooled thermal shrouds is measured and mapped to the thermal mesh to create the temperature field in the ESATAN part as boundary conditions. Both models comprise switches to easily
Thermal Residual Stress in Environmental Barrier Coated Silicon Nitride - Modeled
Ali, Abdul-Aziz; Bhatt, Ramakrishna T.
2009-01-01
When exposed to combustion environments containing moisture both un-reinforced and fiber reinforced silicon based ceramic materials tend to undergo surface recession. To avoid surface recession environmental barrier coating systems are required. However, due to differences in the elastic and thermal properties of the substrate and the environmental barrier coating, thermal residual stresses can be generated in the coated substrate. Depending on their magnitude and nature thermal residual stresses can have significant influence on the strength and fracture behavior of coated substrates. To determine the maximum residual stresses developed during deposition of the coatings, a finite element model (FEM) was developed. Using this model, the thermal residual stresses were predicted in silicon nitride substrates coated with three environmental coating systems namely barium strontium aluminum silicate (BSAS), rare earth mono silicate (REMS) and earth mono di-silicate (REDS). A parametric study was also conducted to determine the influence of coating layer thickness and material parameters on thermal residual stress. Results indicate that z-direction stresses in all three systems are small and negligible, but maximum in-plane stresses can be significant depending on the composition of the constituent layer and the distance from the substrate. The BSAS and REDS systems show much lower thermal residual stresses than REMS system. Parametric analysis indicates that in each system, the thermal residual stresses can be decreased with decreasing the modulus and thickness of the coating.
Cao, Xinhua; Liu, Xue; Chen, Liming; Mao, Yueyuan; Lan, Haichuang; Yi, Tao
2015-11-15
A two-component gel containing long chain alkylated gallic acid (GA) and photochromic phenazopyridine (PAP) was prepared. The gel was thoroughly characterized by UV-visible and IR spectra, SEM and POM images, XRD diffraction and dynamic oscillatory measurements. The structure and transparency of the two-component gel can be reversibly changed by alternative UV light irradiation and warming in the palm of the hand. This kind of soft material has potential application in upscale surface functional materials.
Competitive Adsorption of a Two-Component Gas on a Deformable Adsorbent
Usenko, A. S.
2013-01-01
We investigate the competitive adsorption of a two-component gas on the surface of an adsorbent whose adsorption properties vary in adsorption due to the adsorbent deformation. The essential difference of adsorption isotherms for a deformable adsorbent both from the classical Langmuir adsorption isotherms of a two-component gas and from the adsorption isotherms of a one-component gas taking into account variations in adsorption properties of the adsorbent in adsorption is obtained. We establi...
Evolution and phyletic distribution of two-component signal transduction systems
Wuichet, Kristin; Cantwell, Brian J.; Zhulin, Igor B.
2010-01-01
Two-component signal transduction systems are abundant in prokaryotes. They enable cells to adjust multiple cellular functions in response to changing environmental conditions. These systems are also found, although in much smaller numbers, in lower eukaryotes and plants, where they appear to control a few very specific functions. Two-component systems have evolved in Bacteria from much simpler one-component systems bringing about the benefit of extracellular versus intracellular sensing. We ...
Variational derivation of two-component Camassa-Holm shallow water system
Ionescu-Kruse, Delia
2012-01-01
By a variational approach in the Lagrangian formalism, we derive the nonlinear integrable two-component Camassa-Holm system (1). We show that the two-component Camassa-Holm system (1) with the plus sign arises as an approximation to the Euler equations of hydrodynamics for propagation of irrotational shallow water waves over a flat bed. The Lagrangian used in the variational derivation is not a metric.
Chloroplast two-component systems: evolution of the link between photosynthesis and gene expression
Puthiyaveetil, Sujith; Allen, John F.
2009-01-01
Two-component signal transduction, consisting of sensor kinases and response regulators, is the predominant signalling mechanism in bacteria. This signalling system originated in prokaryotes and has spread throughout the eukaryotic domain of life through endosymbiotic, lateral gene transfer from the bacterial ancestors and early evolutionary precursors of eukaryotic, cytoplasmic, bioenergetic organelles—chloroplasts and mitochondria. Until recently, it was thought that two-component systems i...
Thermal boundary resistance from transient nanocalorimetry: A multiscale modeling approach
Caddeo, Claudia; Melis, Claudio; Ronchi, Andrea; Giannetti, Claudio; Ferrini, Gabriele; Rurali, Riccardo; Colombo, Luciano; Banfi, Francesco
2017-02-01
The thermal boundary resistance at the interface between a nanosized Al film and an Al2O3 substrate is investigated at an atomistic level. The thermal dynamics occurring in time-resolved thermoreflectance experiments is then modeled via macrophysics equations upon insertion of the materials parameters obtained from atomistic simulations. Electrons and phonons nonequilibrium and spatiotemporal temperatures inhomogeneities are found to persist up to the nanosecond time scale. These results question the validity of the commonly adopted lumped thermal capacitance model in interpreting transient nanocalorimetry experiments. The strategy adopted in the literature to extract the thermal boundary resistance from transient reflectivity traces is revised in the light of the present findings. The results are of relevance beyond the specific system, the physical picture being general and readily extendable to other heterojunctions.
First wall thermal hydraulic models for fusion blankets
Energy Technology Data Exchange (ETDEWEB)
Fillo, J A
1980-01-01
Subject to normal and off-normal reactor conditions, thermal hydraulic models of first walls, e.g., a thermal mass barrier, a tubular shield, and a radiating liner are reviewed. Under normal operation the plasma behaves as expected in a predicted way for transient and steady-state conditions. The most severe thermal loading on the first wall occurs when the plasma becomes unstable and dumps its energy on the wall in a very short period of time (milliseconds). Depending on the plasma dump time and area over which the energy is deposited may result in melting of the first wall surface, and if the temperature is high enough, vaporization.
Physical-Statistical Model of Thermal Conductivity of Nanofluids
Directory of Open Access Journals (Sweden)
B. Usowicz
2014-01-01
Full Text Available A physical-statistical model for predicting the effective thermal conductivity of nanofluids is proposed. The volumetric unit of nanofluids in the model consists of solid, liquid, and gas particles and is treated as a system made up of regular geometric figures, spheres, filling the volumetric unit by layers. The model assumes that connections between layers of the spheres and between neighbouring spheres in the layer are represented by serial and parallel connections of thermal resistors, respectively. This model is expressed in terms of thermal resistance of nanoparticles and fluids and the multinomial distribution of particles in the nanofluids. The results for predicted and measured effective thermal conductivity of several nanofluids (Al2O3/ethylene glycol-based and Al2O3/water-based; CuO/ethylene glycol-based and CuO/water-based; and TiO2/ethylene glycol-based are presented. The physical-statistical model shows a reasonably good agreement with the experimental results and gives more accurate predictions for the effective thermal conductivity of nanofluids compared to existing classical models.
Two-component mediated peroxide sensing and signal transduction in fission yeast.
Quinn, Janet; Malakasi, Panagiota; Smith, Deborah A; Cheetham, Jill; Buck, Vicky; Millar, Jonathan B A; Morgan, Brian A
2011-07-01
Two-component related proteins play a major role in regulating the oxidative stress response in the fission yeast, Schizosaccharomyces pombe. For example, the peroxide-sensing Mak2 and Mak3 histidine kinases regulate H(2)O(2)-induced activation of the Sty1 stress-activated protein kinase pathway, and the Skn7-related response regulator transcription factor, Prr1, is essential for activation of the core oxidative stress response genes. Here, we investigate the mechanism by which the S. pombe two-component system senses H(2)O(2), and the potential role of two-component signaling in the regulation of Prr1. Significantly, we demonstrate that PAS and GAF domains present in the Mak2 histidine kinase are essential for redox-sensing and activation of Sty1. In addition, we find that Prr1 is required for the transcriptional response to a wide range of H(2)O(2) concentrations and, furthermore, that two-component regulation of Prr1 is specifically required for the response of cells to high levels of H(2)O(2). Significantly, this provides the first demonstration that the conserved two-component phosphorylation site on Skn7-related proteins influences resistance to oxidative stress and oxidative stress-induced gene expression. Collectively, these data provide new insights into the two-component mediated sensing and signaling mechanisms underlying the response of S. pombe to oxidative stress.
Christensen, Steen; Serbus, Laura Renee
2015-03-24
Two-component regulatory systems are commonly used by bacteria to coordinate intracellular responses with environmental cues. These systems are composed of functional protein pairs consisting of a sensor histidine kinase and cognate response regulator. In contrast to the well-studied Caulobacter crescentus system, which carries dozens of these pairs, the streamlined bacterial endosymbiont Wolbachia pipientis encodes only two pairs: CckA/CtrA and PleC/PleD. Here, we used bioinformatic tools to compare characterized two-component system relays from C. crescentus, the related Anaplasmataceae species Anaplasma phagocytophilum and Ehrlichia chaffeensis, and 12 sequenced Wolbachia strains. We found the core protein pairs and a subset of interacting partners to be highly conserved within Wolbachia and these other Anaplasmataceae. Genes involved in two-component signaling were positioned differently within the various Wolbachia genomes, whereas the local context of each gene was conserved. Unlike Anaplasma and Ehrlichia, Wolbachia two-component genes were more consistently found clustered with metabolic genes. The domain architecture and key functional residues standard for two-component system proteins were well-conserved in Wolbachia, although residues that specify cognate pairing diverged substantially from other Anaplasmataceae. These findings indicate that Wolbachia two-component signaling pairs share considerable functional overlap with other α-proteobacterial systems, whereas their divergence suggests the potential for regulatory differences and cross-talk.
Exercises in 80223 Numerical Modelling of Thermal Processing of Materials
DEFF Research Database (Denmark)
Frandsen, Jens Ole
This exercise book contains exercise instructions for the 7 compulsory exercises (Exercise 1-7) and the final exercise (Exercise 8) in the course 80223 'Numerical Modelling of Thermal Processing of Materials'. The exercise book also contains written program examples in 'C' and 'Pascal'. Finally...... by contacting the secretary on the ground floor of building 425. Please give the following number: TM 99.05 (TM = Thermal processing of Materials)...
Bolot, Rodolphe; Deng, Sihao; Cai, Zhenhua; Liao, Hanlin; Montavon, Ghislain
2014-02-01
Offline robot trajectory generation is now often used for thermal spray applications, especially for complex design parts, requiring enhanced trajectories. This technique allows decreasing the downtime of the thermal spray cell and insures the generation of optimized trajectories. Heat transfers caused by thermal spray increase the workpiece temperature during the coating application. This temperature acts directly on the resulting thermal stresses after cooling of the part down to the ambient temperature. In this study, a coupling was developed between the robot trajectory and computation of the thermal history of the workpiece during the spray operation. The method is based on the storage of the real robot trajectory (i.e., accurate in time) in a text file, and reading of this file with a C programming performed with ANSYS/FLUENT commercial code which allows computing the displacement of the thermal sources according to the trajectory and solving the transient heat conservation equation during the torch displacement. The contributions of the impinging plasma jet and the molten particle jet are taken into account in the model.
Thermal model of attic systems with radiant barriers
Energy Technology Data Exchange (ETDEWEB)
Wilkes, K.E.
1991-07-01
This report summarizes the first phase of a project to model the thermal performance of radiant barriers. The objective of this phase of the project was to develop a refined model for the thermal performance of residential house attics, with and without radiant barriers, and to verify the model by comparing its predictions against selected existing experimental thermal performance data. Models for the thermal performance of attics with and without radiant barriers have been developed and implemented on an IBM PC/AT computer. The validity of the models has been tested by comparing their predictions with ceiling heat fluxes measured in a number of laboratory and field experiments on attics with and without radiant barriers. Cumulative heat flows predicted by the models were usually within about 5 to 10 percent of measured values. In future phases of the project, the models for attic/radiant barrier performance will be coupled with a whole-house model and further comparisons with experimental data will be made. Following this, the models will be utilized to provide an initial assessment of the energy savings potential of radiant barriers in various configurations and under various climatic conditions. 38 refs., 14 figs., 22 tabs.
Effective Thermal Conductivity Modeling of Sandstones: SVM Framework Analysis
Rostami, Alireza; Masoudi, Mohammad; Ghaderi-Ardakani, Alireza; Arabloo, Milad; Amani, Mahmood
2016-06-01
Among the most significant physical characteristics of porous media, the effective thermal conductivity (ETC) is used for estimating the thermal enhanced oil recovery process efficiency, hydrocarbon reservoir thermal design, and numerical simulation. This paper reports the implementation of an innovative least square support vector machine (LS-SVM) algorithm for the development of enhanced model capable of predicting the ETCs of dry sandstones. By means of several statistical parameters, the validity of the presented model was evaluated. The prediction of the developed model for determining the ETCs of dry sandstones was in excellent agreement with the reported data with a coefficient of determination value ({R}2) of 0.983 and an average absolute relative deviation of 0.35 %. Results from present research show that the proposed LS-SVM model is robust, reliable, and efficient in calculating the ETCs of sandstones.
Modeling thermally active building components using space mapping
DEFF Research Database (Denmark)
Pedersen, Frank; Weitzmann, Peter; Svendsen, Svend
2005-01-01
In order to efficiently implement thermally active building components in new buildings, it is necessary to evaluate the thermal interaction between them and other building components. Applying parameter investigation or numerical optimization methods to a differential-algebraic (DAE) model....... This paper describes the principle of the space mapping technique, and introduces a simple space mapping technique. The technique is applied to a lumped parameter model of a thermo active component, which provides a model of the thermal performance of the component as a function of two design parameters...... of a building provides a systematic way of estimating efficient building designs. However, using detailed numerical calculations of the components in the building is a time consuming process, which may become prohibitive if the DAE model is to be used for parameter variation or optimization. Unfortunately...
Thermal model of the Eurodish Solar Stirling Engine
Energy Technology Data Exchange (ETDEWEB)
Garcia Granados, F. J.; Silva Perez, M. a.; Ruiz-Hernandez, V.
2006-07-01
One parabolic dish Stirling engine system has been in operation at the Engineering School of Seville since March 2004. This system is one of the several Country Reference Units of the EnviroDish project, and is based on the Eurodish system. The system has achieved a maximum thermal efficiency (solar to electricity) close to 20% during operation. The analysis of the different parameters suggests a high potential for improvement. A thermal model of the main components of the engine package (cavity, receiver and Stirling engine) can help to evaluate possible modifications of the system and identify the most promising ones. The development of such thermal model and its comparison with experimental data gathered during this period, are reported in this work. Model results exhibit good qualitative agreement with the available measurements. However, the validation of the model will require measuring more parameters at the cavity, receiver and engine. (Author)
Rock thermal conductivity as key parameter for geothermal numerical models
Di Sipio, Eloisa; Chiesa, Sergio; Destro, Elisa; Galgaro, Antonio; Giaretta, Aurelio; Gola, Gianluca; Manzella, Adele
2013-04-01
The geothermal energy applications are undergoing a rapid development. However, there are still several challenges in the successful exploitation of geothermal energy resources. In particular, a special effort is required to characterize the thermal properties of the ground along with the implementation of efficient thermal energy transfer technologies. This paper focuses on understanding the quantitative contribution that geosciences can receive from the characterization of rock thermal conductivity. The thermal conductivity of materials is one of the main input parameters in geothermal modeling since it directly controls the steady state temperature field. An evaluation of this thermal property is required in several fields, such as Thermo-Hydro-Mechanical multiphysics analysis of frozen soils, designing ground source heat pumps plant, modeling the deep geothermal reservoirs structure, assessing the geothermal potential of subsoil. Aim of this study is to provide original rock thermal conductivity values useful for the evaluation of both low and high enthalpy resources at regional or local scale. To overcome the existing lack of thermal conductivity data of sedimentary, igneous and metamorphic rocks, a series of laboratory measurements has been performed on several samples, collected in outcrop, representative of the main lithologies of the regions included in the VIGOR Project (southern Italy). Thermal properties tests were carried out both in dry and wet conditions, using a C-Therm TCi device, operating following the Modified Transient Plane Source method.Measurements were made at standard laboratory conditions on samples both water saturated and dehydrated with a fan-forced drying oven at 70 ° C for 24 hr, for preserving the mineral assemblage and preventing the change of effective porosity. Subsequently, the samples have been stored in an air-conditioned room while bulk density, solid volume and porosity were detected. The measured thermal conductivity
Modeling of droplet dynamic and thermal behaviour during spray deposition
Indian Academy of Sciences (India)
N S Mahesh; Johnson Mendonca; M K Muralidhara; B K Muralidhara; C Ramachandra
2003-04-01
Mathematical modeling of supersonic gas atomization for spray forming has been investigated. Influence of the droplet dynamic and thermal behaviour on the resultant microstructure has been studied. Analytical models have been constructed taking into account the higher Reynolds number owing to supersonic gas flow. The impact velocity profiles of the droplets lend credence to the evolution of equiaxed grain morphology through dendrite fragmentation. The thermal history profile along with the fraction solid plot could yield optimized standoff distance to obtain a mushy droplet. A comparison of secondary dendrite arm spacing obtained from the mathematical model showed good agreement with experimental observations.
Thermal margin comparison between DAM and simple model
Energy Technology Data Exchange (ETDEWEB)
Cha, Jeonghun; Yook, Daesik [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)
2017-01-15
The nuclear industry in Korea, has considered using a detail analysis model (DAM), which described each rod, to get more thermal margin with the design a dry storage facility for nuclear spent fuel (NSF). A DAM is proposed and a thermal analysis to determine the cladding integrity is performed using test conditions with a homogenized NSF assembly analysis model(Simple model). The result show that according to USA safety criteria, temperature of canister surface has to keep below 500 K in normal condition and 630 K in excess condition. A commercial Computational Fluid Dynamics (CFD) called ANSYS Fluent version 14.5 was used.
Champion, D J; Kramer, M; Keith, M J; Bailes, M; Barr, E D; Bates, S D; Bhat, N D R; Burgay, M; Burke-Spolaor, S; Flynn, C M L; Jameson, A; Johnston, S; Ng, C; Levin, L; Possenti, A; Stappers, B W; van Straten, W; Tiburzi, C; Lyne, A G
2015-01-01
The detection of five new fast radio bursts (FRBs) found in the High Time Resolution Universe high latitude survey is presented. The rate implied is 6$^{+4}_{-3}\\times~10^3$ (95%) FRBs sky$^{-1}$ day$^{-1}$ above a fluence of between 0.13 and 5.9 Jy ms for FRBs between 0.128 and 262 ms in duration. One of these FRBs has a clear two-component profile, each component is similar to the known population of single component FRBs and are separated by 2.4(4) ms. All the FRB components appear to be unresolved following deconvolution with a scattering tail and accounting for intra-channel smearing. The two-component FRB also has the highest dispersion measure (1629 pc cm$^{-3}$) of any FRB to-date. Many of the proposed models to explain FRBs use a single high energy event involving compact objects (such as neutron star mergers) and therefore cannot easily explain a two-component FRB. Models that are based on extreme versions of flaring, pulsing or orbital events however could produce multiple component profiles. The c...
Modelling of single bubble-dynamics and thermal effects
Papoulias, D.; Gavaises, M.
2015-12-01
This paper evaluates the solution effects of different Rayleigh-Plesset models (R-P) for simulating the growth/collapse dynamics and thermal behaviour of homogeneous gas bubbles. The flow inputs used for the discrete cavitation bubble calculations are obtained from Reynolds-averaged Navier-Stokes simulations (RANS), performed in high-pressure nozzle holes. Parametric 1-D results are presented for the classical thermal R-P equation [1] as well as for refined models which incorporated compressibility corrections and thermal effects [2, 3]. The thermal bubble model is coupled with the energy equation, which provides the temperature of the bubble as a function of conduction/convection and radiation heat-transfer mechanisms. For approximating gas pressure variations a high-order virial equation of state (EOS) was used, based on Helmholtz free energy principle [4]. The coded thermal R-P model was validated against experimental measurements [5] and model predictions [6] reported in single-bubble sonoluminescence (SBSL).
Thermal and mechanical modelling of convergent plate margins
van den Beukel, P.J.
1990-01-01
In this thesis, the thermal and mechanical structure of convergent plate margins will be investigated by means of numerical modelling. In addition, we will discuss the implications of modelling results for geological processes such as metamorphism or the break-up of a plate at a convergent plate
Gravitational collapse and thermalization in the hard wall model
Craps, Ben; Rosen, Christopher; Taliotis, Anastasios; Vanhoof, Joris; Zhang, Hongbao
2014-01-01
We study a simple example of holographic thermalization in a confining field theory: the homogeneous injection of energy in the hard wall model. Working in an amplitude expansion, we find black brane formation for sufficiently fast energy injection and a scattering wave solution for sufficiently slow injection. We comment on our expectations for more sophisticated holographic QCD models.
Thermal and mechanical modelling of convergent plate margins
van den Beukel, P.J.
1990-01-01
In this thesis, the thermal and mechanical structure of convergent plate margins will be investigated by means of numerical modelling. In addition, we will discuss the implications of modelling results for geological processes such as metamorphism or the break-up of a plate at a convergent plate mar
Thermal and mechanical modelling of convergent plate margins
Beukel, P.J. van den
1990-01-01
In this thesis, the thermal and mechanical structure of convergent plate margins will be investigated by means of numerical modelling. In addition, we will discuss the implications of modelling results for geological processes such as metamorphism or the break-up of a plate at a convergent plate mar
Modeling and optimal design of multilayer thermal cantilever microactuators
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
A model of curvature and tip deflection of multilayer thermal cantilever actuators is derived.The sim-plified expression received from the model avoids inverting complex matrices enhances understanding and makes it easier to optimize the structure parameters.Experiment is performed,the modeled and experimental results demonstrate the validity of the model,and it also indicates that Young’s module makes great contribution to the deflection;therefore,thin layers cannot be ignored arbitrarily.
Statistical Design Model (SDM) of satellite thermal control subsystem
Mirshams, Mehran; Zabihian, Ehsan; Aarabi Chamalishahi, Mahdi
2016-07-01
Satellites thermal control, is a satellite subsystem that its main task is keeping the satellite components at its own survival and activity temperatures. Ability of satellite thermal control plays a key role in satisfying satellite's operational requirements and designing this subsystem is a part of satellite design. In the other hand due to the lack of information provided by companies and designers still doesn't have a specific design process while it is one of the fundamental subsystems. The aim of this paper, is to identify and extract statistical design models of spacecraft thermal control subsystem by using SDM design method. This method analyses statistical data with a particular procedure. To implement SDM method, a complete database is required. Therefore, we first collect spacecraft data and create a database, and then we extract statistical graphs using Microsoft Excel, from which we further extract mathematical models. Inputs parameters of the method are mass, mission, and life time of the satellite. For this purpose at first thermal control subsystem has been introduced and hardware using in the this subsystem and its variants has been investigated. In the next part different statistical models has been mentioned and a brief compare will be between them. Finally, this paper particular statistical model is extracted from collected statistical data. Process of testing the accuracy and verifying the method use a case study. Which by the comparisons between the specifications of thermal control subsystem of a fabricated satellite and the analyses results, the methodology in this paper was proved to be effective. Key Words: Thermal control subsystem design, Statistical design model (SDM), Satellite conceptual design, Thermal hardware
Quantifying the relevance of adaptive thermal comfort models in moderate thermal climate zones
Energy Technology Data Exchange (ETDEWEB)
Hoof, Joost van; Hensen, Jan L.M. [Faculty of Architecture, Building and Planning, Technische Universiteit Eindhoven, Vertigo 6.18, P.O. Box 513, 5600 MB Eindhoven (Netherlands)
2007-01-15
Standards governing thermal comfort evaluation are on a constant cycle of revision and public review. One of the main topics being discussed in the latest round was the introduction of an adaptive thermal comfort model, which now forms an optional part of ASHRAE Standard 55. Also on a national level, adaptive thermal comfort guidelines come into being, such as in the Netherlands. This paper discusses two implementations of the adaptive comfort model in terms of usability and energy use for moderate maritime climate zones by means of literature study, a case study comprising temperature measurements, and building performance simulation. It is concluded that for moderate climate zones the adaptive model is only applicable during summer months, and can reduce energy for naturally conditioned buildings. However, the adaptive thermal comfort model has very limited application potential for such climates. Additionally we suggest a temperature parameter with a gradual course to replace the mean monthly outdoor air temperature to avoid step changes in optimum comfort temperatures. (author)
Direct molecular dynamics simulation of liquid-solid phase equilibria for two-component plasmas.
Schneider, A S; Hughto, J; Horowitz, C J; Berry, D K
2012-06-01
We determine the liquid-solid phase diagram for carbon-oxygen and oxygen-selenium plasma mixtures using two-phase molecular dynamics simulations. We identify liquid, solid, and interface regions using a bond angle metric. To study finite-size effects, we perform 27,648- and 55,296-ion simulations. To help monitor nonequilibrium effects, we calculate diffusion constants D(i). For the carbon-oxygen system we find that D(O) for oxygen ions in the solid is much smaller than D(C) for carbon ions and that both diffusion constants are 80 or more times smaller than diffusion constants in the liquid phase. There is excellent agreement between our carbon-oxygen phase diagram and that predicted by Medin and Cumming. This suggests that errors from finite-size and nonequilibrium effects are small and that the carbon-oxygen phase diagram is now accurately known. The oxygen-selenium system is a simple two-component model for more complex rapid proton capture nucleosynthesis ash compositions for an accreting neutron star. Diffusion of oxygen, in a predominantly selenium crystal, is remarkably fast, comparable to diffusion in the liquid phase. We find a somewhat lower melting temperature for the oxygen-selenium system than that predicted by Medin and Cumming. This is probably because of electron screening effects.
Vortices with scalar condensates in two-component Ginzburg-Landau systems
Forgacs, Peter
2016-01-01
In a class of two-component Ginzburg-Landau models (TCGL) with a U(1)$\\times$U(1) symmetric potential, vortices with a condensate at their core may have significantly lower energies than the Abrikosov-Nielsen-Olesen (ANO) ones. On the example of liquid metallic hydrogen (LMH) above the critical temperature for protons we show that the ANO vortices become unstable against core-condensation, while condensate-core (CC) vortices are stable. For LMH the ratio of the masses of the two types of condensates, $M=m_2/m_1$ is large, and then as a consequence the energy per flux quantum of the vortices, $E_n/n$ becomes a non-monotonous function of the number of flux quanta, $n$. This leads to yet another manifestation of neither type 1 nor type 2, (type 1.5) superconductivity: superconducting and normal domains coexist while various "giant" vortices form. We note that LMH provides a particularly clean example of type 1.5 state as the interband coupling between electronic and protonic Cooper-pairs is forbidden.
Osmotic Second Virial Coefficients of Aqueous Solutions from Two-Component Equations of State.
Cerdeiriña, Claudio A; Widom, B
2016-12-29
Osmotic second virial coefficients in dilute aqueous solutions of small nonpolar solutes are calculated from three different two-component equations of state. The solutes are five noble gases, four diatomics, and six hydrocarbons in the range C1-C4. The equations of state are modified versions of the van der Waals, Redlich-Kwong, and Peng-Robinson equations, with an added hydrogen-bonding term for the solvent water. The parameters in the resulting equations of state are assigned so as to reproduce the experimental values and temperature dependence of the density, vapor pressure, and compressibility of the solvent, the gas-phase second virial coefficient of the pure solute, the solubility and partial molecular volume of the solute, and earlier estimates of the solutes' molecular radii. For all 15 solutes, the calculations are done for 298.15 K, whereas for CH4, C2H6, and C3H8 in particular, they are also done as functions of temperature over the full range 278.15-348.15 K. The calculated osmotic virial coefficients are compared with earlier calculations of these coefficients for these solutes and also with the results derived from earlier computer simulations of model aqueous solutions of methane. They are also compared with the experimental gas-phase second virial coefficients of the pure gaseous solutes to determine the effect the mediation of the solvent has on the resulting solute-solute interactions in the solution.
Adhesion-induced phase behavior of two-component membranes and vesicles.
Rouhiparkouhi, Tahereh; Weikl, Thomas R; Discher, Dennis E; Lipowsky, Reinhard
2013-01-22
The interplay of adhesion and phase separation is studied theoretically for two-component membranes that can phase separate into two fluid phases such as liquid-ordered and liquid-disordered phases. Many adhesion geometries provide two different environments for these membranes and then partition the membranes into two segments that differ in their composition. Examples are provided by adhering vesicles, by hole- or pore-spanning membranes, and by membranes supported by chemically patterned surfaces. Generalizing a lattice model for binary mixtures to these adhesion geometries, we show that the phase behavior of the adhering membranes depends, apart from composition and temperature, on two additional parameters, the area fraction of one membrane segment and the affinity contrast between the two segments. For the generic case of non-vanishing affinity contrast, the adhering membranes undergo two distinct phase transitions and the phase diagrams in the composition/temperature plane have a generic topology that consists of two two-phase coexistence regions separated by an intermediate one-phase region. As a consequence, phase separation and domain formation is predicted to occur separately in each of the two membrane segments but not in both segments simultaneously. Furthermore, adhesion is also predicted to suppress the phase separation process for certain regions of the phase diagrams. These generic features of the adhesion-induced phase behavior are accessible to experiment.
Modelling LARES temperature distribution and thermal drag
Nguyen, Phuc H
2015-01-01
The LARES satellite, a laser-ranged space experiment to contribute to geophysics observation, and to measure the general relatistic Lense-Thirring effect, has been observed to undergo an anomalous along-track orbital acceleration of -$0.4\\ pm/s^2$ (pm := picometer). This "drag" is not surprising; along track drag has previously been observed with the related LAGEOS satellites (-$3.4\\ pm/s^2$). It is hypothesized that the drag is due to anisotropic thermal radiation from the satellite's exterior. We report the results of numerical computations of the along-track orbital decay of the LARES satellite during the first 105 days after launch. The results depend to a significant degree on the visual and IR absorbance $\\alpha$ and emissivity $\\epsilon$ of the fused silica cube-cornered laser retroreflectors (CCRs). We present results for two values of $\\alpha_{IR}$ = $\\epsilon_{IR}$: 0.82, a standard number for "clean" fused silica; and 0.60, a possible value for silica with slight surface contamination subjected to ...
Argonne Bubble Experiment Thermal Model Development
Energy Technology Data Exchange (ETDEWEB)
Buechler, Cynthia Eileen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-12-03
This report will describe the Computational Fluid Dynamics (CFD) model that was developed to calculate the temperatures and gas volume fractions in the solution vessel during the irradiation. It is based on the model used to calculate temperatures and volume fractions in an annular vessel containing an aqueous solution of uranium . The experiment was repeated at several electron beam power levels, but the CFD analysis was performed only for the 12 kW irradiation, because this experiment came the closest to reaching a steady-state condition. The aim of the study is to compare results of the calculation with experimental measurements to determine the validity of the CFD model.
Guo, Guifang; Long, Bo; Cheng, Bo; Zhou, Shiqiong; Xu, Peng; Cao, Binggang
In order to better understand the thermal abuse behavior of high capacities and large power lithium-ion batteries for electric vehicle application, a three-dimensional thermal model has been developed for analyzing the temperature distribution under abuse conditions. The model takes into account the effects of heat generation, internal conduction and convection, and external heat dissipation to predict the temperature distribution in a battery. Three-dimensional model also considers the geometrical features to simulate oven test, which are significant in larger cells for electric vehicle application. The model predictions are compared to oven test results for VLP 50/62/100S-Fe (3.2 V/55 Ah) LiFePO 4/graphite cells and shown to be in great agreement.
Analytical model for non-thermal pressure in galaxy clusters
Shi, Xun
2014-01-01
Non-thermal pressure in the intracluster gas has been found ubiquitously in numerical simulations, and observed indirectly. In this paper we develop, for the first time, an analytical model for intracluster non-thermal pressure. We write down and solve a first-order differential equation describing the evolution of non-thermal velocity dispersion. This equation is based on insights gained from observations, numerical simulations, and theory of turbulence. The non-thermal energy is sourced, in a self-similar fashion, by the mass growth of clusters via mergers and accretion, and dissipates with a time scale determined by the turnover time of the largest turbulence eddies. Our model predicts a radial profile of non-thermal pressure for relaxed clusters. The non-thermal fraction increases with radius, redshift, and cluster mass, in agreement with numerical simulations. The radial dependence is due to a rapid increase of the dissipation time scale with radii, and the mass and redshift dependence comes from the mas...
Evaluation of Thermal Margin Analysis Models for SMART
Energy Technology Data Exchange (ETDEWEB)
Seo, Kyong Won; Kwon, Hyuk; Hwang, Dae Hyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2011-05-15
Thermal margin of SMART would be analyzed by three different methods. The first method is subchannel analysis by MATRA-S code and it would be a reference data for the other two methods. The second method is an on-line few channel analysis by FAST code that would be integrated into SCOPS/SCOMS. The last one is a single channel module analysis by safety analysis. Several thermal margin analysis models for SMART reactor core by subchannel analysis were setup and tested. We adopted a strategy of single stage analysis for thermal analysis of SMART reactor core. The model should represent characteristics of the SMART reactor core including hot channel. The model should be simple as possible to be evaluated within reasonable time and cost
Exercises in 80223 Numerical Modelling of Thermal Processing of Materials
DEFF Research Database (Denmark)
Frandsen, Jens Ole
Processing of Materials'. The original copy is kept in the archives of TM on the ground floor of building 425. A copy of the exercise book can be made available by contacting the secretary on the ground floor of building 425. Please give the following number: TM 00.01 (TM = Thermal processing of Materials)......This exercise book contains exercise instructions for the 7 compulsory exercises (Exercise 1-7) and the final exercise (Exercise 8) in the course 80223 'Numerical Modelling of Thermal Processing of Materials'. The exercise book also contains written program examples in 'C' and 'Pascal'. Finally......, guidelines are given on how to write the report which has to be handed in at the end of the course. The exercise book is a updated version of the exercise book from 1999. The exercise book is used in the course 42224 'Numerical Process Modelling' which earlier was called 80223 'Numerical Modelling of Thermal...
Simple mixing model for pressurized thermal shock applications
Energy Technology Data Exchange (ETDEWEB)
Chexal, B.; Chao, J.; Nickell, R.; Griesbach, T. (Electric Power Research Inst., Palo Alto, CA (USA))
1983-02-01
The phenomenon of fluid/thermal mixing in the cold leg and downcomer of a Pressurized Water Reactor (PWR) has been a critical issue related to the concern of pressurized thermal shock. The question of imperfect mixing arises when the possibility of cold emergency core cooling water contacting the vessel wall during an overcooling transient could produce thermal stresses large enough to initiate a flaw in a radiation embrittled vessel wall. The temperature of the fluid in contact with the vessel wall is crucial to a determination of vessel integrity since temperature affects both the stresses and the material toughness of the vessel material. A simple mixing model is described which was developed as part of the EPRI pressurized thermal shock program for evaluation of reactor vessel integrity.
Thermal mechanical stress modeling of GCtM seals
Energy Technology Data Exchange (ETDEWEB)
Dai, Steve Xunhu [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Chambers, Robert [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
2015-09-01
Finite-element thermal stress modeling at the glass-ceramic to metal (GCtM) interface was conducted assuming heterogeneous glass-ceramic microstructure. The glass-ceramics were treated as composites consisting of high expansion silica crystalline phases dispersed in a uniform residual glass. Interfacial stresses were examined for two types of glass-ceramics. One was designated as SL16 glass -ceramic, owing to its step-like thermal strain curve with an overall coefficient of thermal expansion (CTE) at 16 ppm/ºC. Clustered Cristobalite is the dominant silica phase in SL16 glass-ceramic. The other, designated as NL16 glass-ceramic, exhibited clusters of mixed Cristobalite and Quartz and showed a near-linear thermal strain curve with a same CTE value.
Characterization and modeling of thermal diffusion and aggregation in nanofluids.
Energy Technology Data Exchange (ETDEWEB)
Gharagozloo, Patricia E.; Goodson, Kenneth E. (Stanford University, Stanford, CA)
2010-05-01
Fluids with higher thermal conductivities are sought for fluidic cooling systems in applications including microprocessors and high-power lasers. By adding high thermal conductivity nanoscale metal and metal oxide particles to a fluid the thermal conductivity of the fluid is enhanced. While particle aggregates play a central role in recent models for the thermal conductivity of nanofluids, the effect of particle diffusion in a temperature field on the aggregation and transport has yet to be studied in depth. The present work separates the effects of particle aggregation and diffusion using parallel plate experiments, infrared microscopy, light scattering, Monte Carlo simulations, and rate equations for particle and heat transport in a well dispersed nanofluid. Experimental data show non-uniform temporal increases in thermal conductivity above effective medium theory and can be well described through simulation of the combination of particle aggregation and diffusion. The simulation shows large concentration distributions due to thermal diffusion causing variations in aggregation, thermal conductivity and viscosity. Static light scattering shows aggregates form more quickly at higher concentrations and temperatures, which explains the increased enhancement with temperature reported by other research groups. The permanent aggregates in the nanofluid are found to have a fractal dimension of 2.4 and the aggregate formations that grow over time are found to have a fractal dimension of 1.8, which is consistent with diffusion limited aggregation. Calculations show as aggregates grow the viscosity increases at a faster rate than thermal conductivity making the highly aggregated nanofluids unfavorable, especially at the low fractal dimension of 1.8. An optimum nanoparticle diameter for these particular fluid properties is calculated to be 130 nm to optimize the fluid stability by reducing settling, thermal diffusion and aggregation.
Thermal analysis of dry eye subjects and the thermal impulse perturbation model of ocular surface.
Zhang, Aizhong; Maki, Kara L; Salahura, Gheorghe; Kottaiyan, Ranjini; Yoon, Geunyoung; Hindman, Holly B; Aquavella, James V; Zavislan, James M
2015-03-01
In this study, we explore the usage of ocular surface temperature (OST) decay patterns to distinguished between dry eye patients with aqueous deficient dry eye (ADDE) and meibomian gland dysfunction (MGD). The OST profiles of 20 dry eye subjects were measured by a long-wave infrared thermal camera in a standardized environment (24 °C, and relative humidity (RH) 40%). The subjects were instructed to blink every 5 s after 20 ∼ 25 min acclimation. Exponential decay curves were fit to the average temperature within a region of the central cornea. We find the MGD subjects have both a higher initial temperature (p thermal impulse perturbation (TIP) model. We conclude that long-wave-infrared thermal imaging is a plausible tool in assisting with the classification of dry eye patient.
The Escherichia coli BarA-UvrY two-component system is a virulence determinant in the urinary tract
Directory of Open Access Journals (Sweden)
Georgellis Dimitris
2006-03-01
Full Text Available Abstract Background The Salmonella enterica BarA-SirA, the Erwinia carotovora ExpS-ExpA, the Vibrio cholerae BarA-VarA and the Pseudomonas spp GacS-GacA all belong to the same orthologous family of two-component systems as the Escherichia coli BarA-UvrY. In the first four species it has been demonstrated that disruption of this two-component system leads to a clear reduction in virulence of the bacteria. Our aim was to determine if the Escherichia coli BarA-UvrY two-component system is connected with virulence using a monkey cystitis model. Results Cystitis was generated in Macaque fascularis monkeys by infecting the bladder with a 1:1 mixture of the uropathogenic Escherichia coli isolate DS17 and a derivative where the uvrY gene had been disrupted with a kanamycin resistance gene. Urine was collected through bladder punctuation at subsequent time intervals and the relative amount of uvrY mutant was determined. This showed that inactivation of the UvrY response regulator leads to a reduced fitness. In similar competitions in culture flasks with Luria Broth (LB the uvrY mutant rather had a higher fitness than the wild type. When the competitions were done in flasks with human urine the uvrY mutant initially had a lower fitness. This was followed by a fluctuation in the level of mutant in the long-term culture, with a pattern that was specific for the individual urines that were tested. Addition of LB to the different urine competition cultures however clearly led to a consistently higher fitness of the uvrY mutant. Conclusion This paper demonstrates that the BarA-UvrY two-component system is a determinant for virulence in a monkey cystitis model. The observed competition profiles strengthen our previous hypothesis that disruption of the BarA-UvrY two-component system impairs the ability of the bacteria to switch between different carbon sources. The urine in the bladder contains several different carbon sources and its composition changes over
Directory of Open Access Journals (Sweden)
Jeffrey M Skerker
2005-10-01
Full Text Available Two-component signal transduction systems, comprised of histidine kinases and their response regulator substrates, are the predominant means by which bacteria sense and respond to extracellular signals. These systems allow cells to adapt to prevailing conditions by modifying cellular physiology, including initiating programs of gene expression, catalyzing reactions, or modifying protein-protein interactions. These signaling pathways have also been demonstrated to play a role in coordinating bacterial cell cycle progression and development. Here we report a system-level investigation of two-component pathways in the model organism Caulobacter crescentus. First, by a comprehensive deletion analysis we show that at least 39 of the 106 two-component genes are required for cell cycle progression, growth, or morphogenesis. These include nine genes essential for growth or viability of the organism. We then use a systematic biochemical approach, called phosphotransfer profiling, to map the connectivity of histidine kinases and response regulators. Combining these genetic and biochemical approaches, we identify a new, highly conserved essential signaling pathway from the histidine kinase CenK to the response regulator CenR, which plays a critical role in controlling cell envelope biogenesis and structure. Depletion of either cenK or cenR leads to an unusual, severe blebbing of cell envelope material, whereas constitutive activation of the pathway compromises cell envelope integrity, resulting in cell lysis and death. We propose that the CenK-CenR pathway may be a suitable target for new antibiotic development, given previous successes in targeting the bacterial cell wall. Finally, the ability of our in vitro phosphotransfer profiling method to identify signaling pathways that operate in vivo takes advantage of an observation that histidine kinases are endowed with a global kinetic preference for their cognate response regulators. We propose that this
Lubin, Emma A.; Ashenberg, Orr; Skerker, Jeffrey M.; Laub, Michael T.
2010-01-01
Two-component signal transduction systems enable bacteria to sense and respond to a wide range of environmental stimuli. Sensor histidine kinases transmit signals to their cognate response regulators via phosphorylation. The faithful transmission of information through two-component pathways and the avoidance of unwanted cross-talk require exquisite specificity of histidine kinase-response regulator interactions to ensure that cells mount the appropriate response to external signals. To identify putative specificity-determining residues, we have analyzed amino acid coevolution in two-component proteins and identified a set of residues that can be used to rationally rewire a model signaling pathway, EnvZ-OmpR. To explore how a relatively small set of residues can dictate partner selectivity, we combined alanine-scanning mutagenesis with an approach we call trajectory-scanning mutagenesis, in which all mutational intermediates between the specificity residues of EnvZ and another kinase, RstB, were systematically examined for phosphotransfer specificity. The same approach was used for the response regulators OmpR and RstA. Collectively, the results begin to reveal the molecular mechanism by which a small set of amino acids enables an individual kinase to discriminate amongst a large set of highly-related response regulators and vice versa. Our results also suggest that the mutational trajectories taken by two-component signaling proteins following gene or pathway duplication may be constrained and subject to differential selective pressures. Only some trajectories allow both the maintenance of phosphotransfer and the avoidance of unwanted cross-talk. PMID:21124821
Skerker, Jeffrey M; Prasol, Melanie S; Perchuk, Barrett S; Biondi, Emanuele G
2005-01-01
Two-component signal transduction systems, comprised of histidine kinases and their response regulator substrates, are the predominant means by which bacteria sense and respond to extracellular signals. These systems allow cells to adapt to prevailing conditions by modifying cellular physiology, including initiating programs of gene expression, catalyzing reactions, or modifying protein–protein interactions. These signaling pathways have also been demonstrated to play a role in coordinating bacterial cell cycle progression and development. Here we report a system-level investigation of two-component pathways in the model organism Caulobacter crescentus. First, by a comprehensive deletion analysis we show that at least 39 of the 106 two-component genes are required for cell cycle progression, growth, or morphogenesis. These include nine genes essential for growth or viability of the organism. We then use a systematic biochemical approach, called phosphotransfer profiling, to map the connectivity of histidine kinases and response regulators. Combining these genetic and biochemical approaches, we identify a new, highly conserved essential signaling pathway from the histidine kinase CenK to the response regulator CenR, which plays a critical role in controlling cell envelope biogenesis and structure. Depletion of either cenK or cenR leads to an unusual, severe blebbing of cell envelope material, whereas constitutive activation of the pathway compromises cell envelope integrity, resulting in cell lysis and death. We propose that the CenK–CenR pathway may be a suitable target for new antibiotic development, given previous successes in targeting the bacterial cell wall. Finally, the ability of our in vitro phosphotransfer profiling method to identify signaling pathways that operate in vivo takes advantage of an observation that histidine kinases are endowed with a global kinetic preference for their cognate response regulators. We propose that this system
Bott, Michael; Brocker, Melanie
2012-06-01
In bacteria, adaptation to changing environmental conditions is often mediated by two-component signal transduction systems. In the prototypical case, a specific stimulus is sensed by a membrane-bound histidine kinase and triggers autophosphorylation of a histidine residue. Subsequently, the phosphoryl group is transferred to an aspartate residue of the cognate response regulator, which then becomes active and mediates a specific response, usually by activating and/or repressing a set of target genes. In this review, we summarize the current knowledge on two-component signal transduction in Corynebacterium glutamicum. This Gram-positive soil bacterium is used for the large-scale biotechnological production of amino acids and can also be applied for the synthesis of a wide variety of other products, such as organic acids, biofuels, or proteins. Therefore, C. glutamicum has become an important model organism in industrial biotechnology and in systems biology. The type strain ATCC 13032 possesses 13 two-component systems and the role of five has been elucidated in recent years. They are involved in citrate utilization (CitAB), osmoregulation and cell wall homeostasis (MtrAB), adaptation to phosphate starvation (PhoSR), adaptation to copper stress (CopSR), and heme homeostasis (HrrSA). As C. glutamicum does not only face changing conditions in its natural environment, but also during cultivation in industrial bioreactors of up to 500 m(3) volume, adaptability can also be crucial for good performance in biotechnological production processes. Detailed knowledge on two-component signal transduction and regulatory networks therefore will contribute to both the application and the systemic understanding of C. glutamicum and related species.
A Thermal Model for Carbon Nanotube Interconnects
Mohsin, Kaji Muhammad; Srivastava, Ashok; Sharma, Ashwani K.; Mayberry, Clay
2013-01-01
In this work, we have studied Joule heating in carbon nanotube based very large scale integration (VLSI) interconnects and incorporated Joule heating influenced scattering in our previously developed current transport model. The theoretical model explains breakdown in carbon nanotube resistance which limits the current density. We have also studied scattering parameters of carbon nanotube (CNT) interconnects and compared with the earlier work. For 1 µm length single-wall carbon nanotube, 3 dB frequency in S12 parameter reduces to ~120 GHz from 1 THz considering Joule heating. It has been found that bias voltage has little effect on scattering parameters, while length has very strong effect on scattering parameters.
Thermal-hydraulic modeling of reactivity accidents in MTR reactors
Directory of Open Access Journals (Sweden)
Khater Hany
2006-01-01
Full Text Available This paper describes the development of a dynamic model for the thermal-hydraulic analysis of MTR research reactors during a reactivity insertion accident. The model is formulated for coupling reactor kinetics with feedback reactivity and reactor core thermal-hydraulics. To represent the reactor core, two types of channels are considered, average and hot channels. The developed computer program is compiled and executed on a personal computer, using the FORTRAN language. The model is validated by safety-related benchmark calculations for MTR-TYPE reactors of IAEA 10 MW generic reactor for both slow and fast reactivity insertion transients. A good agreement is shown between the present model and the benchmark calculations. Then, the model is used for simulating the uncontrolled withdrawal of a control rod of an ETRR-2 reactor in transient with over power scram trip. The model results for ETRR-2 are analyzed and discussed.
Thermal hydraulic model descrition of TASS/SMR
Energy Technology Data Exchange (ETDEWEB)
Yoon, Han Young; Kim, H. C.; Chung, Y. J.; Lim, H. S.; Yang, S. H
2001-04-01
The TASS/SMR code has been developed for the safety analysis of SMART. The governing equations were applied only to the primary coolant system in TASS which had been developed at KAERI. In TASS/SMR, the solution method is improved so that the primary and secondary coolant systems are solved simultaneously. Besides the solution method, thermal-hydraulic models are incorporated, in TASS/SMR, such as non-condensible gas model, helical steam generator heat transfer model, and passive residual heat removal system (PRHRS) heat transfer model for the application to SMART. The governing equtions of TASS/SMR are based on the drift-flux model so that the accidents and transients accompaning with two-phase flow can be analized. This report describes the governing equations and solution methods used in TASS/SMR and also includes the description for the thermal hydraulic models for SMART design.
Comparisons between different models for thermal simulation of GTAW process
Institute of Scientific and Technical Information of China (English)
Xu Yanli; Wei Yanhong
2005-01-01
Two mathematical models are built to study the effects of the fluid flow on thermal distributions of the gas tungsten arc welding(GTAW) process. One model is based on the heat conductivity equation, which doesn' t take the effects of the fluid flow into account, and the other couples the laminar heat transfer and fluid flow in the weld pool, which is called laminar fluid flow model in short. The simulated results of the two models show that the pattern and velocity of the fluid flow play a critical role in determining the thermal distribution and the weld pool shape. For the laminar fluid flow model, its highest temperature is 400 K lower than that calculated with the other model and the depth of its weld pool is shallower too, which is mainly caused by the main vortex of the flow in the weld pool.
Process optimization of friction stir welding based on thermal models
DEFF Research Database (Denmark)
Larsen, Anders Astrup
2010-01-01
This thesis investigates how to apply optimization methods to numerical models of a friction stir welding process. The work is intended as a proof-of-concept using different methods that are applicable to models of high complexity, possibly with high computational cost, and without the possibility...... information of the high-fidelity model. The optimization schemes are applied to stationary thermal models of differing complexity of the friction stir welding process. The optimization problems considered are based on optimizing the temperature field in the workpiece by finding optimal translational speed....... Also an optimization problem based on a microstructure model is solved, allowing the hardness distribution in the plate to be optimized. The use of purely thermal models represents a simplification of the real process; nonetheless, it shows the applicability of the optimization methods considered...
Quantitative Kinetic Analyses of Shutting Off a Two-Component System
Directory of Open Access Journals (Sweden)
Rong Gao
2017-05-01
Full Text Available Cells rely on accurate control of signaling systems to adapt to environmental perturbations. System deactivation upon stimulus removal is as important as activation of signaling pathways. The two-component system (TCS is one of the major bacterial signaling schemes. In many TCSs, phosphatase activity of the histidine kinase (HK is believed to play an essential role in shutting off the pathway and resetting the system to the prestimulus state. Two basic challenges are to understand the dynamic behavior of system deactivation and to quantitatively evaluate the role of phosphatase activity under natural cellular conditions. Here we report a kinetic analysis of the response to shutting off the archetype Escherichia coli PhoR-PhoB TCS pathway using both transcription reporter assays and in vivo phosphorylation analyses. Upon removal of the stimulus, the pathway is shut off by rapid dephosphorylation of the PhoB response regulator (RR while PhoB-regulated gene products gradually reset to prestimulus levels through growth dilution. We developed an approach combining experimentation and modeling to assess in vivo kinetic parameters of the phosphatase activity with kinetic data from multiple phosphatase-diminished mutants. This enabled an estimation of the PhoR phosphatase activity in vivo, which is much stronger than the phosphatase activity of PhoR cytoplasmic domains analyzed in vitro. We quantitatively modeled how strong the phosphatase activity needs to be to suppress nonspecific phosphorylation in TCSs and discovered that strong phosphatase activity of PhoR is required for cross-phosphorylation suppression.
Temporal Variability from the Two-Component Advective Flow Solution and Its Observational Evidence
Dutta, Broja G.; Chakrabarti, Sandip K.
2016-09-01
In the propagating oscillatory shock model, the oscillation of the post-shock region, i.e., the Compton cloud, causes the observed low-frequency quasi-periodic oscillations (QPOs). The evolution of QPO frequency is explained by the systematic variation of the Compton cloud size, i.e., the steady radial movement of the shock front, which is triggered by the cooling of the post-shock region. Thus, analysis of the energy-dependent temporal properties in different variability timescales can diagnose the dynamics and geometry of accretion flows around black holes. We study these properties for the high-inclination black hole source XTE J1550-564 during its 1998 outburst and the low-inclination black hole source GX 339-4 during its 2006-07 outburst using RXTE/PCA data, and we find that they can satisfactorily explain the time lags associated with the QPOs from these systems. We find a smooth decrease of the time lag as a function of time in the rising phase of both sources. In the declining phase, the time lag increases with time. We find a systematic evolution of QPO frequency and hard lags in these outbursts. In XTE J1550-564, the lag changes from hard to soft (i.e., from a positive to a negative value) at a crossing frequency (ν c) of ˜3.4 Hz. We present possible mechanisms to explain the lag behavior of high and low-inclination sources within the framework of a single two-component advective flow model.
Features of Functioning the Integrated Building Thermal Model
Directory of Open Access Journals (Sweden)
Morozov Maxim N.
2017-01-01
Full Text Available A model of the building heating system, consisting of energy source, a distributed automatic control system, elements of individual heating unit and heating system is designed. Application Simulink of mathematical package Matlab is selected as a platform for the model. There are the specialized application Simscape libraries in aggregate with a wide range of Matlab mathematical tools allow to apply the “acausal” modeling concept. Implementation the “physical” representation of the object model gave improving the accuracy of the models. Principle of operation and features of the functioning of the thermal model is described. The investigations of building cooling dynamics were carried out.
New mass loss kinetic model for thermal decomposition of biomass
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Based on non-isothermal experimental results for eight Chinese biomass species, a new kinetic model,named as the "pseudo bi-component separate-stage model (PBSM)", is developed in this note to describe the mass loss behavior of biomass thermal decomposition. This model gains an advantage over the commonly used "pseudo single-component overall model (PSOM)" and "pseudo multi-component overall model (PMOM)". By means of integral analysis it is indicated that the new model is suitable to describe the mass loss kinetics of wood and leaf samples under relatively low heating rates (e.g. 10°C/rin, used in this work).``
A thermal conductivity model for U-Si compounds
Energy Technology Data Exchange (ETDEWEB)
Zhang, Yongfeng [Idaho National Lab. (INL), Idaho Falls, ID (United States); Andersson, Anders David Ragnar [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-02-02
U_{3}Si_{2} is a candidate for accident tolerant nuclear fuel being developed as an alternative to UO_{2} in commercial light water reactors (LWRs). One of its main benefits compared to UO_{2} is higher thermal conductivity that increases with temperature. This increase is contrary to UO_{2}, for which the thermal conductivity decreases with temperature. The reason for the difference is the electronic origin of thermal conductivity in U_{3}Si_{2}, as compared to the phonon mechanism responsible for thermal transport in UO_{2}. The phonon thermal conductivity in UO_{2} is unusually low for a fluorite oxide due to the strong interaction with the spins in the paramagnetic phase. The thermal conductivity of U_{3}Si_{2} as well as other U-Si compounds has been measured experimentally [1-4]. However, for fuel performance simulations it is also critical to model the degradation of the thermal conductivity due to damage and microstructure evolution caused by the reactor environment (irradiation and high temperature). For UO_{2} this reduction is substantial and it has been the topic of extensive NEAMS research resulting in several publications [5, 6]. There are no data or models for the evolution of the U_{3}Si_{2} thermal conductivity under irradiation. We know that the intrinsic thermal conductivities of UO_{2} (semi-conductor) and U_{3}Si_{2} (metal) are very different, and we do not necessarily expect the dependence on damage to be the same either, which could present another advantage for the silicide fuel. In this report we summarize the first step in developing a model for the thermal conductivity of U-Si compounds with the goal of capturing the effect of damage in U_{3}Si_{2}. Next year, we will focus on lattice damage. We will also attempt to assess the impact of fission gas bubbles.
A Thermal Model for Carbon Nanotube Interconnects
Directory of Open Access Journals (Sweden)
Clay Mayberry
2013-04-01
Full Text Available In this work, we have studied Joule heating in carbon nanotube based very large scale integration (VLSI interconnects and incorporated Joule heating influenced scattering in our previously developed current transport model. The theoretical model explains breakdown in carbon nanotube resistance which limits the current density. We have also studied scattering parameters of carbon nanotube (CNT interconnects and compared with the earlier work. For 1 µm length single-wall carbon nanotube, 3 dB frequency in S12 parameter reduces to ~120 GHz from 1 THz considering Joule heating. It has been found that bias voltage has little effect on scattering parameters, while length has very strong effect on scattering parameters.
Modeling of thermal processes in spherical area
Demyanchenko, O.; Lyashenko, V.
2016-10-01
In this paper a mathematical model of the temperature field in spherical area with complex conditions of heat exchange with the environment is considered. The solution of the nonlinear initial boundary value problem is reduced to the solution of the nonlinear integral equation of Fredholm type respect to spatial coordinates and Volterra with the kernel in the form of the Green's function on the time coordinate.
Radiative Transport Modelling of Thermal Barrier Coatings
2017-03-24
traveled by signal and reference beam photons) is the result of signal photons travelling a distance L through the sample . Since this distance L is related...performed in both tasks together for convenience . First, we briefly discuss the random walk model, since it is relevant in the discussion on both the...Figure 7, whereby a collinear low coherence beam (shown as a red arrow) is considered to be incident onto the sample at normal incidence to the surface
Thermal modeling of wafer-based precision glass molding process
Hu, Yang; Shen, Lianguan; Zhou, Jian; Li, Mujun
2016-10-01
Wafer based precision glass optics manufacturing has been an innovative approach for combining high accuracy with mass production. However, due to the small ratio of thickness and diameter of the glass wafer, deformation and residual stress would be induced for the nonuniform temperature distribution in the glass wafer after molding. Therefore, thermal modelling of the heating system in the wafer based precision glass molding (PGM) process is of great importance in optimizing the heating system and the technique of the process. The current paper deals with a transient thermal modelling of a self-developed heating system for wafer based PGM process. First, in order to investigate the effect of radiation from the surface and interior of the glass wafer, the thermal modeling is simulated with a discrete ordinates radiation model in the CFD software FLUENT. Temperature distribution of the glass wafer obtained from the simulations is then used to evaluate the performance of heating system and investigate some importance parameters in the model, such as interior and surface radiation in glass wafer, thermal contact conductance between glass wafer and molds, thickness to diameter ratio of glass wafer. Finally, structure modification in the molding chamber is raised to decrease the temperature gradient in the glass wafer and the effect is significant.
Modeling thermal/chemical/mechanical response of energetic materials
Energy Technology Data Exchange (ETDEWEB)
Baer, M.R.; Hobbs, M.L.; Gross, R.J. [and others
1995-07-01
An overview of modeling at Sandia National Laboratories is presented which describes coupled thermal, chemical and mechanical response of energetic materials. This modeling addresses cookoff scenarios for safety assessment studies in systems containing energetic materials. Foundation work is discussed which establishes a method for incorporating chemistry and mechanics into multidimensional analysis. Finite element analysis offers the capabilities to simultaneously resolve reactive heat transfer and structural mechanics in complex geometries. Nonlinear conduction heat transfer, with multiple step finite-rate chemistry, is resolved using a thermal finite element code. Rate equations are solved element-by-element using a modified matrix-free stiff solver This finite element software was developed for the simulation of systems requiring large numbers of finite elements. An iterative implicit scheme, based on the conjugate gradient method, is used and a hemi-cube algorithm is employed for the determination of view factors in surface-to-surface radiation transfer The critical link between the reactive heat transfer and mechanics is the introduction of an appropriate constitutive material model providing a stress-strain relationship for quasi-static mechanics analysis. This model is formally derived from bubble nucleation theory, and parameter variations of critical model parameters indicate that a small degree of decomposition leads to significant mechanical response. Coupled thermal/chemical/mechanical analysis is presented which simulates experiments designed to probe cookoff thermal-mechanical response of energetic materials.
Numerical Modeling of Water Thermal Plumes Emitted by Thermal Power Plants
Directory of Open Access Journals (Sweden)
Azucena Durán-Colmenares
2016-10-01
Full Text Available This work focuses on the study of thermal dispersion of plumes emitted by power plants into the sea. Wastewater discharge from power stations causes impacts that require investigation or monitoring. A study to characterize the physical effects of thermal plumes into the sea is carried out here by numerical modeling and field measurements. The case study is the thermal discharges of the Presidente Adolfo López Mateos Power Plant, located in Veracruz, on the coast of the Gulf of Mexico. This plant is managed by the Federal Electricity Commission of Mexico. The physical effects of such plumes are related to the increase of seawater temperature caused by the hot water discharge of the plant. We focus on the implementation, calibration, and validation of the Delft3D-FLOW model, which solves the shallow-water equations. The numerical simulations consider a critical scenario where meteorological and oceanographic parameters are taken into account to reproduce the proper physical conditions of the environment. The results show a local physical effect of the thermal plumes within the study zone, given the predominant strong winds conditions of the scenario under study.
Low scale thermal leptogenesis in neutrinophilic Higgs doublet models
Haba, Naoyuki
2011-01-01
It is well-known that leptogenesis in low energy scale is difficult in the conventional Type-I seesaw mechanism with hierarchical right-handed neutrino masses. We show that in a class of two Higgs doublet model, where one Higgs doublet generates masses of quarks and charged leptons whereas the other Higgs doublet with a tiny vacuum expectation value generates neutrino Dirac masses, large Yukawa couplings lead to a large enough CP asymmetry of the right-handed neutrino decay. Thermal leptogenesis suitably works at low energy scale as keeping no enhancement of lepton number violating wash out effects. We will also point out that thermal leptogenesis works well without confronting gravitino problem in a supersymmetric neutrinophilic Higgs doublet model with gravity mediated supersymmetry breaking. Neutralino dark matter and baryon asymmetry generation by thermal leptogenesis are easily compatible in our setup.
Phenomenological vs. biophysical models of thermal stress in aquatic eggs.
Martin, Benjamin T; Pike, Andrew; John, Sara N; Hamda, Natnael; Roberts, Jason; Lindley, Steven T; Danner, Eric M
2017-01-01
Predicting species responses to climate change is a central challenge in ecology. These predictions are often based on lab-derived phenomenological relationships between temperature and fitness metrics. We tested one of these relationships using the embryonic stage of a Chinook salmon population. We parameterised the model with laboratory data, applied it to predict survival in the field, and found that it significantly underestimated field-derived estimates of thermal mortality. We used a biophysical model based on mass transfer theory to show that the discrepancy was due to the differences in water flow velocities between the lab and the field. This mechanistic approach provides testable predictions for how the thermal tolerance of embryos depends on egg size and flow velocity of the surrounding water. We found support for these predictions across more than 180 fish species, suggesting that flow and temperature mediated oxygen limitation is a general mechanism underlying the thermal tolerance of embryos.
Hydrocarbons Heterogeneous Pyrolysis: Experiments and Modeling for Scramjet Thermal Management
Bouchez, Marc; Visez, Nicolas; Herbinet, Olivier; Fournet, René; Marquaire, Paul-Marie
2009-01-01
The last years saw a renewal of interest for hypersonic research in general and regenerative cooling specifically, with a large increase of the number of dedicated facilities and technical studies. In order to quantify the heat transfer in the cooled structures and the composition of the cracked fuel entering the combustor, an accurate model of the thermal decomposition of the fuel is required. This model should be able to predict the fuel chemical composition and physical properties for a broad range of pressures, temperatures and cooling geometries. For this purpose, an experimental and modeling study of the thermal decomposition of generic molecules (long-chain or polycyclic alkanes) that could be good surrogates of real fuels, has been started at the DCPR laboratory located in Nancy (France). This successful effort leads to several versions of a complete kinetic model. These models do not assume any effect from the material that constitutes the cooling channel. A specific experimental study was performed ...
Block algebra in two-component BKP and D type Drinfeld-Sokolov hierarchies
Li, Chuanzhong; He, Jingsong
2013-11-01
We construct generalized additional symmetries of a two-component BKP hierarchy defined by two pseudo-differential Lax operators. These additional symmetry flows form a Block type algebra with some modified (or additional) terms because of a B type reduction condition of this integrable hierarchy. Further we show that the D type Drinfeld-Sokolov hierarchy, which is a reduction of the two-component BKP hierarchy, possess a complete Block type additional symmetry algebra. That D type Drinfeld-Sokolov hierarchy has a similar algebraic structure as the bigraded Toda hierarchy which is a differential-discrete integrable system.
Rabi Oscillations in Two-Component Bose-Einstein Condensates with a Coupling Drive
Institute of Scientific and Technical Information of China (English)
LI Wei-Dong; FAN Wen-Bing; ZHOU Xiao-Ji; WANG Yi-Qiu; LIANG Jiu-Qing
2002-01-01
The Rabi oscillations in two-component Bose-Einstein condensates with a coupling drive are studiedby means of a pair of bosonic operators. The coupling drive and initial phase difference will affect the amplitudeand the period of the Rabi oscillations. The Rabi oscillations will vanish in the evolution of the condensate densityfor some special initial phase differences (ψ = 0 or π). Our theory provides not only an analytical framework forquantitative predictions for two-component condensates, but also gives an intuitive understanding of some mysteriousfeatures observed in experiments and numerical. simulations.
Targeting two-component signal transduction: a novel drug discovery system.
Okada, Ario; Gotoh, Yasuhiro; Watanabe, Takafumi; Furuta, Eiji; Yamamoto, Kaneyoshi; Utsumi, Ryutaro
2007-01-01
We have developed two screening systems for isolating inhibitors that target bacterial two-component signal transduction: (1) a differential growth assay using a temperature-sensitive yycF mutant (CNM2000) of Bacillus subtilis, which is supersensitive to histidine kinase inhibitors, and (2) a high-throughput genetic system for targeting the homodimerization of histidine kinases essential for the bacterial two-component signal transduction. By using these methods, we have been able to identify various types of inhibitors that block the autophosphorylation of histidine kinases with different modes of actions.
Block algebra in two-component BKP and D type Drinfeld-Sokolov hierarchies
Energy Technology Data Exchange (ETDEWEB)
Li, Chuanzhong, E-mail: lichuanzhong@nbu.edu.cn; He, Jingsong, E-mail: hejingsong@nbu.edu.cn [Department of Mathematics, Ningbo University, Ningbo 315211 (China)
2013-11-15
We construct generalized additional symmetries of a two-component BKP hierarchy defined by two pseudo-differential Lax operators. These additional symmetry flows form a Block type algebra with some modified (or additional) terms because of a B type reduction condition of this integrable hierarchy. Further we show that the D type Drinfeld-Sokolov hierarchy, which is a reduction of the two-component BKP hierarchy, possess a complete Block type additional symmetry algebra. That D type Drinfeld-Sokolov hierarchy has a similar algebraic structure as the bigraded Toda hierarchy which is a differential-discrete integrable system.
Thermal Error Modelling of the Spindle Using Neurofuzzy Systems
Directory of Open Access Journals (Sweden)
Jingan Feng
2016-01-01
Full Text Available This paper proposes a new combined model to predict the spindle deformation, which combines the grey models and the ANFIS (adaptive neurofuzzy inference system model. The grey models are used to preprocess the original data, and the ANFIS model is used to adjust the combined model. The outputs of the grey models are used as the inputs of the ANFIS model to train the model. To evaluate the performance of the combined model, an experiment is implemented. Three Pt100 thermal resistances are used to monitor the spindle temperature and an inductive current sensor is used to obtain the spindle deformation. The experimental results display that the combined model can better predict the spindle deformation compared to BP network, and it can greatly improve the performance of the spindle.
Thermal resistance model for CSP central receivers
de Meyer, O. A. J.; Dinter, F.; Govender, S.
2016-05-01
The receiver design and heliostat field aiming strategy play a vital role in the heat transfer efficiency of the receiver. In molten salt external receivers, the common operating temperature of the heat transfer fluid or molten salt ranges between 285°C to 565°C. The optimum output temperature of 565°C is achieved by adjusting the mass flow rate of the molten salt through the receiver. The reflected solar radiation onto the receiver contributes to the temperature rise in the molten salt by means of heat transfer. By investigating published work on molten salt external receiver operating temperatures, corresponding receiver tube surface temperatures and heat losses, a model has been developed to obtain a detailed thermographic representation of the receiver. The steady state model uses a receiver flux map as input to determine: i) heat transfer fluid mass flow rate through the receiver to obtain the desired molten salt output temperature of 565°C, ii) receiver surface temperatures iii) receiver tube temperatures iv) receiver efficiency v) pressure drop across the receiver and vi) corresponding tube strain per panel.
Dynamic modelling for a submerged freeze microgripper using thermal networks
López-Walle, Beatriz; Gauthier, Michaël; Chaillet, Nicolas
2010-02-01
The growing interest in micromanipulation systems requires efficient, reliable and flexible handling strategies. Recent studies have demonstrated that performing manipulations and assembly in liquid surroundings is more advantageous than in dry conditions, especially when objects are below 100 µm in size. The thermally actuated ice microgripper proposed and analysed in this paper is designed to operate in a completely submerged manner in an aqueous medium. The handling principle benefits from the adhesive properties of ice, its thermal control principle is based on the Peltier effect, some features of the prototype and the first micromanipulation tests are summarized. This paper is focused on the modelling of the thermal microhandling system using an electrical analogy. The submerged microgripper is split into different subsystems which are studied in order to identify their thermal network. Then they are interconnected to build the whole thermal network of the submerged microgripper. This model is validated by comparison with experimental measurements. Controlling the temperatures involved in our device will be the purpose of further works.
Thermal Infrared Observations and Thermophysical Modeling of Phobos
Smith, Nathan Michael; Edwards, Christopher Scott; Mommert, Michael; Trilling, David E.; Glotch, Timothy
2016-10-01
Mars-observing spacecraft have the opportunity to study Phobos from Mars orbit, and have produced a sizeable record of observations using the same instruments that study the surface of the planet below. However, these observations are generally infrequent, acquired only rarely over each mission.Using observations gathered by Mars Global Surveyor's (MGS) Thermal Emission Spectrometer (TES), we can investigate the fine layer of regolith that blankets Phobos' surface, and characterize its thermal properties. The mapping of TES observations to footprints on the Phobos surface has not previously been undertaken, and must consider the orientation and position of both MGS and Phobos, and TES's pointing mirror angle. Approximately 300 fully resolved observations are available covering a significant subset of Phobos' surface at a variety of scales.The properties of the surface regolith, such as grain size, density, and conductivity, determine how heat is absorbed, transferred, and reradiated to space. Thermophysical modeling allows us to simulate these processes and predict, for a given set of assumed parameters, how the observed thermal infrared spectra will appear. By comparing models to observations, we can constrain the properties of the regolith, and see how these properties vary with depth, as well as regionally across the Phobos surface. These constraints are key to understanding how Phobos formed and evolved over time, which in turn will help inform the environment and processes that shaped the solar system as a whole.We have developed a thermophysical model of Phobos adapted from a model used for unresolved observations of asteroids. The model has been modified to integrate thermal infrared flux across each observed portion of Phobos. It will include the effects of surface roughness, temperature-dependent conductivity, as well as radiation scattered, reflected, and thermally emitted from the Martian surface. Combining this model with the newly-mapped TES
Friction at seismic slip rates: testing thermal weakening models experimentally
Nielsen, S. B.; Spagnuolo, E.; Violay, M.; Di Toro, G.
2013-12-01
Recent experiments systematically explore rock friction under crustal earthquake conditions (fast slip rate 1desing an efficient and accurate wavenumber approximation for a solution of the temperature evolution on the fault. Finally, we propose a compact and paractical model based on a small number of memory variables for the implementation of thermal weakening friction in seismic fault simulations.
A Review of the Modelling of Thermally Interacting Multiple Boreholes
Directory of Open Access Journals (Sweden)
Seama Koohi-Fayegh
2013-06-01
Full Text Available Much attention is now focused on utilizing ground heat pumps for heating and cooling buildings, as well as water heating, refrigeration and other thermal tasks. Modeling such systems is important for understanding, designing and optimizing their performance and characteristics. Several heat transfer models exist for ground heat exchangers. In this review article, challenges of modelling heat transfer in vertical heat exchangers are described, some analytical and numerical models are reviewed and compared, recent related developments are described and the importance of modelling these systems is discussed from a variety of aspects, such as sustainability of geothermal systems or their potential impacts on the ecosystems nearby.
Eguchi, Yoko; Ishii, Eiji; Hata, Kensuke; Utsumi, Ryutaro
2011-03-01
Two-component signal transduction systems (TCSs), utilized extensively by bacteria and archaea, are involved in the rapid adaptation of the organisms to fluctuating environments. A typical TCS transduces the signal by a phosphorelay between the sensor histidine kinase and its cognate response regulator. Recently, small-sized proteins that link TCSs have been reported and are called "connectors." Their physiological roles, however, have remained elusive. SafA (sensor associating factor A) (formerly B1500), a small (65-amino-acid [65-aa]) membrane protein, is among such connectors and links Escherichia coli TCSs EvgS/EvgA and PhoQ/PhoP. Since the activation of the EvgS/EvgA system induces acid resistance, we examined whether the SafA-activated PhoQ/PhoP system is also involved in the acid resistance induced by EvgS/EvgA. Using a constitutively active evgS1 mutant for the activation of EvgS/EvgA, we found that SafA, PhoQ, and PhoP all contributed to the acid resistance phenotype. Moreover, EvgS/EvgA activation resulted in the accumulation of cellular RpoS in the exponential-phase cells in a SafA-, PhoQ-, and PhoP-dependent manner. This RpoS accumulation was caused by another connector, IraM, expression of which was induced by the activation of the PhoQ/PhoP system, thus preventing RpoS degradation by trapping response regulator RssB. Acid resistance assays demonstrated that IraM also participated in the EvgS/EvgA-induced acid resistance. Therefore, we propose a model of a signal transduction cascade proceeding from EvgS/EvgA to PhoQ/PhoP and then to RssB (connected by SafA and IraM) and discuss its contribution to the acid resistance phenotype.
A second order anti-diffusive Lagrange-remap scheme for two-component flows
Directory of Open Access Journals (Sweden)
Lagoutière Frédéric
2011-11-01
Full Text Available We build a non-dissipative second order algorithm for the approximate resolution of the one-dimensional Euler system of compressible gas dynamics with two components. The considered model was proposed in [1]. The algorithm is based on [8] which deals with a non-dissipative first order resolution in Lagrange-remap formalism. In the present paper we describe, in the same framework, an algorithm that is second order accurate in time and space, and that preserves sharp interfaces. Numerical results reported at the end of the paper are very encouraging, showing the interest of the second order accuracy for genuinely non-linear waves. Nous construisons un algorithme d’ordre deux et non dissipatif pour la résolution approchée des équations d’Euler de la dynamique des gaz compressibles à deux constituants en dimension un. Le modèle que nous considérons est celui à cinq équations proposé et analysé dans [1]. L’algorithme est basé sur [8] qui proposait une résolution approchée à l’ordre un et non dissipative au moyen d’un splitting de type Lagrange-projection. Dans le présent article, nous décrivons, dans le même formalisme, un algorithme d’ordre deux en temps et en espace, qui préserve des interfaces « parfaites » entre les constituants. Les résultats numériques rapportés à la fin de l’article sont très encourageants ; ils montrent clairement les avantages d’un schéma d’ordre deux pour les ondes vraiment non linéaires.
Numerical modeling of Thermal Response Tests in Energy Piles
Franco, A.; Toledo, M.; Moffat, R.; Herrera, P. A.
2013-05-01
Nowadays, thermal response tests (TRT) are used as the main tools for the evaluation of low enthalpy geothermal systems such as heat exchangers. The results of TRT are used for estimating thermal conductivity and thermal resistance values of those systems. We present results of synthetic TRT simulations that model the behavior observed in an experimental energy pile system, which was installed at the new building of the Faculty of Engineering of Universidad de Chile. Moreover, we also present a parametric study to identify the most influent parameters in the performance of this type of tests. The modeling was developed using the finite element software COMSOL Multiphysics, which allows the incorporation of flow and heat transport processes. The modeled system consists on a concrete pile with 1 m diameter and 28 m deep, which contains a 28 mm diameter PEX pipe arranged in a closed circuit. Three configurations were analyzed: a U pipe, a triple U and a helicoid shape implemented at the experimental site. All simulations were run considering transient response in a three-dimensional domain. The simulation results provided the temperature distribution on the pile for a set of different geometry and physical properties of the materials. These results were compared with analytical solutions which are commonly used to interpret TRT data. This analysis demonstrated that there are several parameters that affect the system response in a synthetic TRT. For example, the diameter of the simulated pile affects the estimated effective thermal conductivity of the system. Moreover, the simulation results show that the estimated thermal conductivity for a 1 m diameter pile did not stabilize even after 100 hours since the beginning of the test, when it reached a value 30% below value used to set up the material properties in the simulation. Furthermore, we observed different behaviors depending on the thermal properties of concrete and soil. According to the simulations, the thermal
House thermal model parameter estimation method for Model Predictive Control applications
van Leeuwen, Richard Pieter; de Wit, J.B.; Fink, J.; Smit, Gerardus Johannes Maria
2015-01-01
In this paper we investigate thermal network models with different model orders applied to various Dutch low-energy house types with high and low interior thermal mass and containing floor heating. Parameter estimations are performed by using data from TRNSYS simulations. The paper discusses results
House thermal model parameter estimation method for Model Predictive Control applications
van Leeuwen, Richard Pieter; de Wit, J.B.; Fink, J.; Smit, Gerardus Johannes Maria
In this paper we investigate thermal network models with different model orders applied to various Dutch low-energy house types with high and low interior thermal mass and containing floor heating. Parameter estimations are performed by using data from TRNSYS simulations. The paper discusses results
Parametric Thermal Models of the Transient Reactor Test Facility (TREAT)
Energy Technology Data Exchange (ETDEWEB)
Bradley K. Heath
2014-03-01
This work supports the restart of transient testing in the United States using the Department of Energy’s Transient Reactor Test Facility at the Idaho National Laboratory. It also supports the Global Threat Reduction Initiative by reducing proliferation risk of high enriched uranium fuel. The work involves the creation of a nuclear fuel assembly model using the fuel performance code known as BISON. The model simulates the thermal behavior of a nuclear fuel assembly during steady state and transient operational modes. Additional models of the same geometry but differing material properties are created to perform parametric studies. The results show that fuel and cladding thermal conductivity have the greatest effect on fuel temperature under the steady state operational mode. Fuel density and fuel specific heat have the greatest effect for transient operational model. When considering a new fuel type it is recommended to use materials that decrease the specific heat of the fuel and the thermal conductivity of the fuel’s cladding in order to deal with higher density fuels that accompany the LEU conversion process. Data on the latest operating conditions of TREAT need to be attained in order to validate BISON’s results. BISON’s models for TREAT (material models, boundary convection models) are modest and need additional work to ensure accuracy and confidence in results.
Use of advanced modeling techniques to optimize thermal packaging designs.
Formato, Richard M; Potami, Raffaele; Ahmed, Iftekhar
2010-01-01
Through a detailed case study the authors demonstrate, for the first time, the capability of using advanced modeling techniques to correctly simulate the transient temperature response of a convective flow-based thermal shipper design. The objective of this case study was to demonstrate that simulation could be utilized to design a 2-inch-wall polyurethane (PUR) shipper to hold its product box temperature between 2 and 8 °C over the prescribed 96-h summer profile (product box is the portion of the shipper that is occupied by the payload). Results obtained from numerical simulation are in excellent agreement with empirical chamber data (within ±1 °C at all times), and geometrical locations of simulation maximum and minimum temperature match well with the corresponding chamber temperature measurements. Furthermore, a control simulation test case was run (results taken from identical product box locations) to compare the coupled conduction-convection model with a conduction-only model, which to date has been the state-of-the-art method. For the conduction-only simulation, all fluid elements were replaced with "solid" elements of identical size and assigned thermal properties of air. While results from the coupled thermal/fluid model closely correlated with the empirical data (±1 °C), the conduction-only model was unable to correctly capture the payload temperature trends, showing a sizeable error compared to empirical values (ΔT > 6 °C). A modeling technique capable of correctly capturing the thermal behavior of passively refrigerated shippers can be used to quickly evaluate and optimize new packaging designs. Such a capability provides a means to reduce the cost and required design time of shippers while simultaneously improving their performance. Another advantage comes from using thermal modeling (assuming a validated model is available) to predict the temperature distribution in a shipper that is exposed to ambient temperatures which were not bracketed
A thermal inertia model for soil water content retrieval using thermal and multispectral images
Maltese, A.; Minacapilli, M.; Cammalleri, C.; Ciraolo, G.; D'Asaro, F.
2010-10-01
Soil moisture is difficult to quantify because of its high spatial variability. Consequently, great efforts have been undertaken by the research community to develop practical remote sensing approaches to estimate the spatial distribution of surface soil moisture over large areas and with high spatial detail. Many methodologies have been developed using remote sensing data acquiring information in different parts of the electromagnetic spectrum. Conventional field measurement techniques (including gravimetric and time-domain reflectometry) are point-based, involve on-site operators, are time expensive and, in any case, do not provide exhaustive information on the spatial distribution of soil moisture because it strongly depends on pedology, soil roughness and vegetation cover. The technological development of imaging sensors acquiring in the visible (VIS), near infrared (NIR) and thermal infrared (TIR), renewed the research interest in setting up remote sensed based techniques aimed to retrieve soil water content variability in the soil-plant-atmosphere system (SPA). In this context different approaches have been widely applied at regional scale throughout synthetic indexes based on VIS, NIR and TIR spectral bands. A laboratory experiment has been carried out to verify a physically based model based on the remote estimation of the soil thermal inertia, P, to indirectly retrieve the soil surface water content, θ. The paper shows laboratory retrievals using simultaneously a FLIR A320G thermal camera, a six bands customized TETRACAM MCA II (Multiple Camera Array) multispectral camera working in the VIS/NIR part of the spectrum. Using these two type of sensors a set of VIS/NIR and TIR images were acquired as the main input dataset to retrieve the spatial variability of the thermal inertia values. Moreover, given that the accuracy of the proposed approach strongly depends on the accurate estimation of the soil thermal conductivity, a Decagon Device KD2 PRO thermal
Exercises in 80223 Numerical Modelling of Thermal Processing of Materials
DEFF Research Database (Denmark)
Frandsen, Jens Ole
This exercise book contains exercise instructions for the 7 compulsory exercises (Exercise 1-7) and the final exercise (Exercise 8) in the course 80223 'Numerical Modelling of Thermal Processing of Materials'. The exercise book also contains written program examples in 'C' and 'Pascal'. Finally...... Processing of Materials'. The original copy is kept in the archives of TM on the ground floor of building 425. A copy of the exercise book can be made available by contacting the secretary on the ground floor of building 425. Please give the following number: TM 00.01 (TM = Thermal processing of Materials)...
A micro-convection model for thermal conductivity of nanofluids
Indian Academy of Sciences (India)
Hrishikesh E Patel; T Sundararajan; T Pradeep; A Dasgupta; N Dasgupta; Sarit K Das
2005-11-01
Increase in the specific surface area as well as Brownian motion are supposed to be the most significant reasons for the anomalous enhancement in thermal conductivity of nanofluids. This work presents a semi-empirical approach for the same by emphasizing the above two effects through micro-convection. A new way of modeling thermal conductivity of nanofluids has been explored which is found to agree excellently with a wide range of experimental data obtained by the present authors as well as the data published in literature.
Three-wave interaction in two-component quadratic nonlinear lattices
DEFF Research Database (Denmark)
Konotop, V. V.; Cunha, M. D.; Christiansen, Peter Leth
1999-01-01
We investigate a two-component lattice with a quadratic nonlinearity and find with the multiple scale technique that integrable three-wave interaction takes place between plane wave solutions when these fulfill resonance conditions. We demonstrate that. energy conversion and pulse propagation kno...
A novel two-component system found in Mycobacterium tuberculosis
DEFF Research Database (Denmark)
Morth, J. P.; Gosmann, S.; Nowak, E.;
2005-01-01
We report the identification of a novel two-component system in Mycobacterium tuberculosis. We show that the putative histidine kinase with the genomic locus tag Rv3220c is able to self-phosphorylate in the presence of Mg2+/ATP and subsequently transfer the phosphoryl group to a novel response...
Light Responsive Two-Component Supramolecular Hydrogel: A Sensitive Platform for Humidity Sensors
Samai, Suman
2016-02-15
The supramolecular assembly of anionic azobenzene dicarboxylate and cationic cetyltrimethylammonium bromide (CTAB) formed a stimuli responsive hydrogel with a critical gelation concentration (CGC) of 0.33 wt%. This self-sustainable two-component system was able to repair damage upon light irradiation. Moreover, it was successfully employed in the fabrication of highly sensitive humidity sensors for the first time.
A Two-Component Generalization of Burgers' Equation with Quasi-Periodic Solution
Pan, Hongfei; Xia, Tiecheng; Chen, Dengyuan
2014-10-01
In this paper, we aim for the theta function representation of quasi-periodic solution and related crucial quantities for a two-component generalization of Burgers' equation. Our tools include the theory of algebraic curves, meromorphic functions, Baker-Akhiezer functions and the Dubrovin-type equations for auxiliary divisor. Eith these tools, the explicit representations for above quantities are obtained.
Two-component Brownian coagulation: Monte Carlo simulation and process characterization
Institute of Scientific and Technical Information of China (English)
Haibo Zhao; Chu guang Zheng
2011-01-01
The compositional distribution within aggregates of a given size is essential to the functionality of composite aggregates that are usually enlarged by rapid Brownian coagulation.There is no analytical solution for the process of such two-component systems.Monte Carlo method is an effective numerical approach for two-component coagulation.In this paper,the differentially weighted Monte Carlo method is used to investigate two-component Brownian coagulation,respectively,in the continuum regime,the freemolecular regime and the transition regime.It is found that ( 1 ) for Brownian coagulation in the continuum regime and in the free-molecular regime,the mono-variate compositional distribution,i.e.,the number density distribution function of one component amount (in the form of volume of the component in aggregates) satisfies self-preserving form the same as particle size distribution in mono-component Brownian coagulation; (2) however,for Brownian coagulation in the transition regime the mono-variate compositional distribution cannot reach self-similarity; and (3) the bivariate compositional distribution,i.e.,the combined number density distribution function of two component amounts in the three regimes satisfies a semi self-preserving form.Moreover,other new features inherent to aggregative mixing are also demonstrated; e.g.,the degree of mixing between components,which is largely controlled by the initial compositional mass fraction,improves as aggregate size increases.
Transport of a two-component mixture in one-dimensional channels
Borman, VD; Tronin, VN; Tronin, [No Value; Troyan, [No Value
2004-01-01
The transport of a two-component gas mixture in subnanometer channels is investigated theoretically for an arbitrary filling of channels. Special attention is paid to consistent inclusion of density effects, which are associated both with the interaction and with a finite size of particles. The anal
The Integrability of New Two-Component KdV Equation
Directory of Open Access Journals (Sweden)
Ziemowit Popowicz
2010-02-01
Full Text Available We consider the bi-Hamiltonian representation of the two-component coupled KdV equations discovered by Drinfel'd and Sokolov and rediscovered by Sakovich and Foursov. Connection of this equation with the supersymmetric Kadomtsev-Petviashvilli-Radul-Manin hierarchy is presented. For this new supersymmetric equation the Lax representation and odd Hamiltonian structure is given.
The Qualitative Analysis of a Solution of a Series Maintenance System with Two Components
Institute of Scientific and Technical Information of China (English)
GUOWei-hua; YANGMing-zeng
2003-01-01
In this paper, firstly we study the series maintenance system with two components, obtain its exsistence and uniqueness of a dynamic state nonnegative solution by strongly continuous semigroups of operators theory. Then we prove that 0 is the eigenvalue of the system's host operators, and finally we study the eigenvector of the eigenvalue 0.
A novel two-component system involved in secretion stress response in Streptomyces lividans.
Directory of Open Access Journals (Sweden)
Sonia Gullón
Full Text Available BACKGROUND: Misfolded proteins accumulating outside the bacterial cytoplasmic membrane can interfere with the secretory machinery, hence the existence of quality factors to eliminate these misfolded proteins is of capital importance in bacteria that are efficient producers of secretory proteins. These bacteria normally use a specific two-component system to respond to the stress produced by the accumulation of the misfolded proteins, by activating the expression of HtrA-like proteases to specifically eliminate the incorrectly folded proteins. METHODOLOGY/PRINCIPAL FINDINGS: Overproduction of alpha-amylase in S. lividans causing secretion stress permitted the identification of a two-component system (SCO4156-SCO4155 that regulates three HtrA-like proteases which appear to be involved in secretion stress response. Mutants in each of the genes forming part of the two-genes operon that encodes the sensor and regulator protein components accumulated misfolded proteins outside the cell, strongly suggesting the involvement of this two-component system in the S. lividans secretion stress response. CONCLUSIONS/SIGNIFICANCE: To our knowledge this is the first time that a specific secretion stress response two-component system is found to control the expression of three HtrA-like protease genes in S. lividans, a bacterium that has been repeatedly used as a host for the synthesis of homologous and heterologous secretory proteins of industrial application.
The essential YycFG two-component system controls cell wall metabolism in Bacillus subtilis
DEFF Research Database (Denmark)
Bisicchia, Paola; Noone, David; Lioliou, Efthimia
2007-01-01
Adaptation of bacteria to the prevailing environmental and nutritional conditions is often mediated by two-component signal transduction systems (TCS). The Bacillus subtilis YycFG TCS has attracted special attention as it is essential for viability and its regulon is poorly defined. Here we show...
Global dissipative solutions for the two-component Camassa-Holm shallow water system
Directory of Open Access Journals (Sweden)
Yujuan Wang
2015-01-01
Full Text Available This article presents a continuous semigroup of globally defined weak dissipative solutions for the two-component Camassa-Holm system. Such solutions are established by using a new approach based on characteristics a set of new variables overcoming the difficulties inherent in multi-component systems.
Phase separation and dynamics of two-component Bose-Einstein condensates
DEFF Research Database (Denmark)
Lee, Kean Loon; Jørgensen, Nils Byg; Liu, I-Kang;
2016-01-01
The miscibility of two interacting quantum systems is an important testing ground for the understanding of complex quantum systems. Two-component Bose-Einstein condensates enable the investigation of this scenario in a particularly well controlled setting. In a homogeneous system, the transition...
Phase of Two-Component Bose-Einstein Condensates with a Coupling Drive
Institute of Scientific and Technical Information of China (English)
YU Zhao-Xian; JIN Shuo; JIAO Zhi-Yong; WANG Ji-Suo
2007-01-01
By using the invariant theory, we study the phases of two-component Bose-Einstein condensates with a coupling drive under the case that the strength of the interatomic interaction in each condensate equals the interspecies interaction. The dynamical and geometric phases are presented respectively. The Aharonov-Anandan phase is also obtained under the cyclical evolution.
Geometric Integrability of Two-Component Camassa-Holm and Hunter-Saxton Systems
Institute of Scientific and Technical Information of China (English)
SONG Juu-Feng; QU Chang-Zheng
2011-01-01
It is shown that the two-component Camassa-Holm and Hunter-Saxton systems are geometrically integrable, namely they describe pseudo-spherical surfaces. As a consequence, their infinite number o, conservation laws are directly constructed. In addition, a class of nonlocal symmetries depending on the pseudo-potentials are obtained.
Transport of a two-component mixture in one-dimensional channels
Borman, VD; Tronin, VN; Tronin, [No Value; Troyan, [No Value
2004-01-01
The transport of a two-component gas mixture in subnanometer channels is investigated theoretically for an arbitrary filling of channels. Special attention is paid to consistent inclusion of density effects, which are associated both with the interaction and with a finite size of particles. The
Combined photovoltaic/thermal solar array dc electrical model
Energy Technology Data Exchange (ETDEWEB)
Krikorian, J.S. Jr.
1981-12-01
An electrical model of a combined photovoltaic/thermal solar array has been developed to predict the steady state behavior of the line currents, power output and array voltage. The effects of temperature on the solar cell characteristics is included in the analysis. The model includes line isolation diodes and ''open cell'' bypass diodes. A numerical procedure based on the Contraction Mapping Fixed Point Theorem is used to solve the associated nonlinear equations. 6 refs.
Fukuoka, Yoshitaka; Ishizuka, Masaru
1989-09-01
In recent years, electronic circuits have been required to be smaller and lighter and to have greater complexity, more multifunctions and higher reliability. High-density multichip packaging technology has been used in order to meet these requirements. The higher the density scale, the larger the power dissipation per unit area will become. Therefore, thermal analysis becomes one of the most important design factors. However, the multichip package heat transport mode is very complex and its treatment is tedious and time consuming. This paper describes an application of the thermal network method and proposes a simple thermal analysis model for the thermal analysis of multichip packages as a preliminary thermal design tool. As a result, the validity of the thermal network method and the simple thermal analysis model can be confirmed.
FASTSAT-HSV01 Thermal Math Model Correlation
McKelvey, Callie
2011-01-01
This paper summarizes the thermal math model correlation effort for the Fast Affordable Science and Technology SATellite (FASTSAT-HSV01), which was designed, built and tested by NASA's Marshall Space Flight Center (MSFC) and multiple partners. The satellite launched in November 2010 on a Minotaur IV rocket from the Kodiak Launch Complex in Kodiak, Alaska. It carried three Earth science experiments and two technology demonstrations into a low Earth circular orbit with an inclination of 72deg and an altitude of 650 kilometers. The mission has been successful to date with science experiment activities still taking place daily. The thermal control system on this spacecraft was a passive design relying on thermo-optical properties and six heaters placed on specific components. Flight temperature data is being recorded every minute from the 48 Resistance Temperature Devices (RTDs) onboard the satellite structure and many of its avionics boxes. An effort has been made to correlate the thermal math model to the flight temperature data using Cullimore and Ring's Thermal Desktop and by obtaining Earth and Sun vector data from the Attitude Control System (ACS) team to create an "as-flown" orbit. Several model parameters were studied during this task to understand the spacecraft's sensitivity to these changes. Many "lessons learned" have been noted from this activity that will be directly applicable to future small satellite programs.
Performance Analysis and Modeling of Thermally Sprayed Resistive Heaters
Lamarre, Jean-Michel; Marcoux, Pierre; Perrault, Michel; Abbott, Richard C.; Legoux, Jean-Gabriel
2013-08-01
Many processes and systems require hot surfaces. These are usually heated using electrical elements located in their vicinity. However, this solution is subject to intrinsic limitations associated with heating element geometry and physical location. Thermally spraying electrical elements directly on surfaces can overcome these limitations by tailoring the geometry of the heating element to the application. Moreover, the element heat transfer is maximized by minimizing the distance between the heater and the surface to be heated. This article is aimed at modeling and characterizing resistive heaters sprayed on metallic substrates. Heaters were fabricated by using a plasma-sprayed alumina dielectric insulator and a wire flame-sprayed iron-based alloy resistive element. Samples were energized and kept at a constant temperature of 425 °C for up to 4 months. SEM cross-sectional observations revealed the formation of cracks at very specific locations in the alumina layer after thermal use. Finite-element modeling shows that these cracks originate from high local thermal stresses and can be predicted according to the considered geometry. The simulation model was refined using experimental parameters obtained by several techniques such as emissivity and time-dependent temperature profile (infra-red camera), resistivity (four-probe technique), thermal diffusivity (laser flash method), and mechanical properties (micro and nanoindentation). The influence of the alumina thickness and the substrate material on crack formation was evaluated.
Advanced Stirling Radioisotope Generator (ASRG) Thermal Power Model in MATLAB
Wang, Xiao-Yen, J.
2012-01-01
This paper presents a one-dimensional steady-state mathematical thermal power model of the ASRG. It aims to provide a guideline of understanding how the ASRG works and what can change its performance. The thermal dynamics and energy balance of the generator is explained using the thermal circuit of the ASRG. The Stirling convertor performance map is used to represent the convertor. How the convertor performance map is coupled in the thermal circuit is explained. The ASRG performance characteristics under i) different sink temperatures and ii) over the years of mission (YOM) are predicted using the one-dimensional model. Two Stirling converter control strategies, i) fixing the hot-end of temperature of the convertor by adjusting piston amplitude and ii) fixing the piston amplitude, were tested in the model. Numerical results show that the first control strategy can result in a higher system efficiency than the second control strategy when the ambient gets warmer or the general-purpose heat source (GPHS) fuel load decays over the YOM. The ASRG performance data presented in this paper doesn't pertain to the ASRG flight unit. Some data of the ASRG engineering unit (EU) and flight unit that are available in public domain are used in this paper for the purpose of numerical studies.
Atomistic Modeling of Thermal Conductivity of Epoxy Nanotube Composites
Fasanella, Nicholas A.; Sundararaghavan, Veera
2016-05-01
The Green-Kubo method was used to investigate the thermal conductivity as a function of temperature for epoxy/single wall carbon nanotube (SWNT) nanocomposites. An epoxy network of DGEBA-DDS was built using the `dendrimer' growth approach, and conductivity was computed by taking into account long-range Coulombic forces via a k-space approach. Thermal conductivity was calculated in the direction perpendicular to, and along the SWNT axis for functionalized and pristine SWNT/epoxy nanocomposites. Inefficient phonon transport at the ends of nanotubes is an important factor in the thermal conductivity of the nanocomposites, and for this reason discontinuous nanotubes were modeled in addition to long nanotubes. The thermal conductivity of the long, pristine SWNT/epoxy system is equivalent to that of an isolated SWNT along its axis, but there was a 27% reduction perpendicular to the nanotube axis. The functionalized, long SWNT/epoxy system had a very large increase in thermal conductivity along the nanotube axis (~700%), as well as the directions perpendicular to the nanotube (64%). The discontinuous nanotubes displayed an increased thermal conductivity along the SWNT axis compared to neat epoxy (103-115% for the pristine SWNT/epoxy, and 91-103% for functionalized SWNT/epoxy system). The functionalized system also showed a 42% improvement perpendicular to the nanotube, while the pristine SWNT/epoxy system had no improvement over epoxy. The thermal conductivity tensor is averaged over all possible orientations to see the effects of randomly orientated nanotubes, and allow for experimental comparison. Excellent agreement is seen for the discontinuous, pristine SWNT/epoxy nanocomposite. These simulations demonstrate there exists a threshold of the SWNT length where the best improvement for a composite system with randomly oriented nanotubes would transition from pristine SWNTs to functionalized SWNTs.
A new thermal comfort approach comparing adaptive and PMV models
Energy Technology Data Exchange (ETDEWEB)
Orosa, Jose A. [Universidade da Coruna, Departamento de Energia y P. M. Paseo de Ronda, n :51, 15011. A Coruna (Spain); Oliveira, Armando C. [Universidade do Porto, Faculdade de Engenharia, New Energy Tec. Unit. Rua Dr Roberto Frias, 4200-465 Porto (Portugal)
2011-03-15
In buildings with heating, ventilation, and air-conditioning (HVAC), the Predicted Mean Vote index (PMV) was successful at predicting comfort conditions, whereas in naturally ventilated buildings, only adaptive models provide accurate predictions. On the other hand, permeable coverings can be considered as a passive control method of indoor conditions and, consequently, have implications in the perception of indoor air quality, local thermal comfort, and energy savings. These energy savings were measured in terms of the set point temperature established in accordance with adaptive methods. Problems appear when the adaptive model suggests the same neutral temperature for ambiences with the same indoor temperature but different relative humidities. In this paper, a new design of the PMV model is described to compare the neutral temperature to real indoor conditions. Results showed that this new PMV model tends to overestimate thermal neutralities but with a lower value than Fanger's PMV index. On the other hand, this new PMV model considers indoor relative humidity, showing a clear differentiation of indoor ambiences in terms of it, unlike adaptive models. Finally, spaces with permeable coverings present indoor conditions closer to thermal neutrality, with corresponding energy savings. (author)
Thermal Environmental Testing of NSTAR Engineering Model Ion Thrusters
Rawlin, Vincent K.; Patterson, Michael J.; Becker, Raymond A.
1999-01-01
NASA's New Millenium program will fly a xenon ion propulsion system on the Deep Space 1 Mission. Tests were conducted under NASA's Solar Electric Propulsion Technology Applications Readiness (NSTAR) Program with 3 different engineering model ion thrusters to determine thruster thermal characteristics over the NSTAR operating range in a variety of thermal environments. A liquid nitrogen-cooled shroud was used to cold-soak the thruster to -120 C. Initial tests were performed prior to a mature spacecraft design. Those results and the final, severe, requirements mandated by the spacecraft led to several changes to the basic thermal design. These changes were incorporated into a final design and tested over a wide range of environmental conditions.
Thermal analysis of charring materials based on pyrolysis interface model
Directory of Open Access Journals (Sweden)
Huang Hai-Ming
2014-01-01
Full Text Available Charring thermal protection systems have been used to protect hypersonic vehicles from high heat loads. The pyrolysis of charring materials is a complicated physical and chemical phenomenon. Based on the pyrolysis interface model, a simulating approach for charring ablation has been designed in order to obtain one dimensional transient thermal behavior of homogeneous charring materials in reentry capsules. As the numerical results indicate, the pyrolysis rate and the surface temperature under a given heat flux rise abruptly in the beginning, then reach a plateau, but the temperature at the bottom rises very slowly to prevent the structural materials from being heated seriously. Pyrolysis mechanism can play an important role in thermal protection systems subjected to serious aerodynamic heat.
Thermal stability of n-dodecane : experiments and kinetic modelling
Herbinet, Olivier; Battin-Leclerc, Frédérique; Fournet, René
2007-01-01
The thermal decomposition of n-dodecane, a component of some jet fuels, has been studied in a jet-stirred reactor at temperatures from 793 to 1093 K, for residence times between 1 and 5 s and at atmospheric pressure. Thermal decomposition of hydrocarbon fuel prior the entrance in the combustion chamber is an envisaged way to cool the wall of hypersonic vehicles. The products of the reaction are mainly hydrogen, methane, ethane, 1,3-butadiene and 1-alkenes from ethylene to 1-undecene. For higher temperatures and residence times acetylene, allene, propyne, cyclopentene, 1,3-cyclopentadiene and aromatic compounds from benzene to pyrene through naphthalene have also been observed. A previous detailed kinetic model of the thermal decomposition of n-dodecane generated using EXGAS software has been improved and completed by a sub-mechanism explaining the formation and the consumption of aromatic compounds.
Energy Technology Data Exchange (ETDEWEB)
Mason, Peter [Laboratoire de Physique Statistique, Ecole Normale Superieure, UPMC Paris 06, Universite Paris Diderot, CNRS, 24 rue Lhomond, F-75005 Paris (France); Institut Jean Le Rond D' Alembert, UMR 7190 CNRS-UPMC, 4 place Jussieu, F-75005 Paris (France); Aftalion, Amandine [CNRS and Universite Versailles-Saint-Quentin-en-Yvelines, Laboratoire de Mathematiques de Versailles, CNRS UMR 8100, 45 avenue des Etats-Unis, F-78035 Versailles Cedex (France)
2011-09-15
We classify the ground states and topological defects of a rotating two-component condensate when varying several parameters: the intracomponent coupling strengths, the intercomponent coupling strength, and the particle numbers. No restriction is placed on the masses or trapping frequencies of the individual components. We present numerical phase diagrams which show the boundaries between the regions of coexistence, spatial separation, and symmetry breaking. Defects such as triangular coreless vortex lattices, square coreless vortex lattices, and giant skyrmions are classified. Various aspects of the phase diagrams are analytically justified thanks to a nonlinear {sigma} model that describes the condensate in terms of the total density and a pseudo-spin representation.
System Thermal Model for the S-Prime Thermionic Reactor
Arx, Alan V. Von
1994-07-01
A model has been developed which numerically simulates heat transfer and flow characteristics of the thermal-hydraulic loop of the S-PRIME thermionic reactor. The components for which detailed models have been included are: the thermionic fuel elements (TFEs), heat pipe panels, flow loop and pumps. The reactor start-up operation was then modeled from zero to full power. It includes modelling of the melting of the heat pipe working fluid as well as correlations for the performance of the thermionic cells. The results show that there is stable operation during this period.
Theoretical Modelling Methods for Thermal Management of Batteries
Directory of Open Access Journals (Sweden)
Bahman Shabani
2015-09-01
Full Text Available The main challenge associated with renewable energy generation is the intermittency of the renewable source of power. Because of this, back-up generation sources fuelled by fossil fuels are required. In stationary applications whether it is a back-up diesel generator or connection to the grid, these systems are yet to be truly emissions-free. One solution to the problem is the utilisation of electrochemical energy storage systems (ESS to store the excess renewable energy and then reusing this energy when the renewable energy source is insufficient to meet the demand. The performance of an ESS amongst other things is affected by the design, materials used and the operating temperature of the system. The operating temperature is critical since operating an ESS at low ambient temperatures affects its capacity and charge acceptance while operating the ESS at high ambient temperatures affects its lifetime and suggests safety risks. Safety risks are magnified in renewable energy storage applications given the scale of the ESS required to meet the energy demand. This necessity has propelled significant effort to model the thermal behaviour of ESS. Understanding and modelling the thermal behaviour of these systems is a crucial consideration before designing an efficient thermal management system that would operate safely and extend the lifetime of the ESS. This is vital in order to eliminate intermittency and add value to renewable sources of power. This paper concentrates on reviewing theoretical approaches used to simulate the operating temperatures of ESS and the subsequent endeavours of modelling thermal management systems for these systems. The intent of this review is to present some of the different methods of modelling the thermal behaviour of ESS highlighting the advantages and disadvantages of each approach.
Duct thermal performance models for large commercial buildings
Energy Technology Data Exchange (ETDEWEB)
Wray, Craig P.
2003-10-01
Despite the potential for significant energy savings by reducing duct leakage or other thermal losses from duct systems in large commercial buildings, California Title 24 has no provisions to credit energy-efficient duct systems in these buildings. A substantial reason is the lack of readily available simulation tools to demonstrate the energy-saving benefits associated with efficient duct systems in large commercial buildings. The overall goal of the Efficient Distribution Systems (EDS) project within the PIER High Performance Commercial Building Systems Program is to bridge the gaps in current duct thermal performance modeling capabilities, and to expand our understanding of duct thermal performance in California large commercial buildings. As steps toward this goal, our strategy in the EDS project involves two parts: (1) developing a whole-building energy simulation approach for analyzing duct thermal performance in large commercial buildings, and (2) using the tool to identify the energy impacts of duct leakage in California large commercial buildings, in support of future recommendations to address duct performance in the Title 24 Energy Efficiency Standards for Nonresidential Buildings. The specific technical objectives for the EDS project were to: (1) Identify a near-term whole-building energy simulation approach that can be used in the impacts analysis task of this project (see Objective 3), with little or no modification. A secondary objective is to recommend how to proceed with long-term development of an improved compliance tool for Title 24 that addresses duct thermal performance. (2) Develop an Alternative Calculation Method (ACM) change proposal to include a new metric for thermal distribution system efficiency in the reporting requirements for the 2005 Title 24 Standards. The metric will facilitate future comparisons of different system types using a common ''yardstick''. (3) Using the selected near-term simulation approach
Energy Technology Data Exchange (ETDEWEB)
Back, Paer-Erik; Sundberg, Jan [Geo Innova AB (Sweden)
2007-09-15
This report presents a strategy for describing, predicting and visualising the thermal aspects of the site descriptive model. The strategy is an updated version of an earlier strategy applied in all SDM versions during the initial site investigation phase at the Forsmark and Oskarshamn areas. The previous methodology for thermal modelling did not take the spatial correlation fully into account during simulation. The result was that the variability of thermal conductivity in the rock mass was not sufficiently well described. Experience from earlier thermal SDMs indicated that development of the methodology was required in order describe the spatial distribution of thermal conductivity in the rock mass in a sufficiently reliable way, taking both variability within rock types and between rock types into account. A good description of the thermal conductivity distribution is especially important for the lower tail. This tail is important for the design of a repository because it affects the canister spacing. The presented approach is developed to be used for final SDM regarding thermal properties, primarily thermal conductivity. Specific objectives for the strategy of thermal stochastic modelling are: Description: statistical description of the thermal conductivity of a rock domain. Prediction: prediction of thermal conductivity in a specific rock volume. Visualisation: visualisation of the spatial distribution of thermal conductivity. The thermal site descriptive model should include the temperature distribution and thermal properties of the rock mass. The temperature is the result of the thermal processes in the repository area. Determination of thermal transport properties can be made using different methods, such as laboratory investigations, field measurements, modelling from mineralogical composition and distribution, modelling from density logging and modelling from temperature logging. The different types of data represent different scales, which has to be
Thermal structure of Svalbard glaciers and implications for thermal switch models of glacier surging
Sevestre, Heïdi; Benn, Douglas I.; Hulton, Nicholas R. J.; Bælum, Karoline
2015-10-01
Switches between cold- and warm-based conditions have long been invoked to explain surges of High Arctic glaciers. Here we compile existing and new data on the thermal regime of six glaciers in Svalbard to test the applicability of thermal switch models. Two of the large glaciers of our sample are water terminating while one is land terminating. All three have a well-known surge history. They have a thick basal layer of temperate ice, superimposed by cold ice. A cold terminus forms during quiescence but is mechanically removed by calving on tidewater glaciers. The other three glaciers are relatively small and are either entirely cold or have a diminishing warm core. All three bear evidence of former warm-based thermal regimes and, in two cases, surge-like behavior during the Little Ice Age. In Svalbard, therefore, three types of glaciers have switched from slow to fast flow: (1) small glaciers that underwent thermal cycles during and following the Little Ice Age (switches between cold- and warm-based conditions), (2) large terrestrial glaciers which remain warm based throughout the entire surge cycle but develop cold termini during quiescence, and (3) large tidewater glaciers that remain warm based throughout the surge cycle. Our results demonstrate that thermal switching cannot explain the surges of large glaciers in Svalbard. We apply the concept of enthalpy cycling to the spectrum of surge and surge-like behavior displayed by these glaciers and demonstrate that all Svalbard surge-type glaciers can be understood within a single conceptual framework.
A Study of Thermal Contact using Nonlinear System Identification Models
Directory of Open Access Journals (Sweden)
M. H. Shojaeefard
2008-01-01
Full Text Available One interesting application of system identification method is to identify and control the heat transfer from the exhaust valve to the seat to keep away the valve from being damaged. In this study, two co-axial cylindrical specimens are used as exhaust valve and its seat. Using the measured temperatures at different locations of the specimens and with a semi-analytical method, the temperature distribution of the specimens is calculated and consequently, the thermal contact conductance is calculated. By applying the system identification method and having the temperatures at both sides of the contact surface, the temperature transfer function is calculated. With regard to the fact that the thermal contact has nonlinear behavior, two nonlinear black-box models called nonlinear ARX and NLN Hammerstein-Wiener models are taken for accurate estimation. Results show that the NLN Hammerstein-Wiener models with wavelet network nonlinear estimator is the best.
Thermal power system analysis using a generalized network flow model
Energy Technology Data Exchange (ETDEWEB)
Kumar, John Arun [Former Senior Design Engineer, Power System Analysis and Control Group, Bharat Heavy Electricals Limited, New Delhi (India); Chebiyam, Radhakrishna [Former Director, Academic Staff College, JNT University, Hyderabad-72 (India)
2012-07-01
This paper analyzes an Integrated Thermal Power System using a Multiperiod Generalized Network Flow Model. The thermal system analysis is carried out by taking into account the complex dynamics involved in utilizing multiple energy carriers (coal, diesel and natural gas). The model comprises energy source nodes, energy transformation nodes, energy storage nodes, energy demand nodes and their interconnections. The solution to the integrated energy system problem involves the evaluation of energy flows that meet the electricity demand at minimum total cost, while satisfying system constraints. This is illustrated through the India case study using a minimum time-step of one hour. MATLAB based software was developed for carrying out this study. TOMLAB/CPLEX software was utilized for obtaining the optimal solution. The model and the methodology utilized for conducting the study would be of interest to those involved in integrated energy system planning for a country or a region.
Fractional Heat Conduction Models and Thermal Diffusivity Determination
Directory of Open Access Journals (Sweden)
Monika Žecová
2015-01-01
Full Text Available The contribution deals with the fractional heat conduction models and their use for determining thermal diffusivity. A brief historical overview of the authors who have dealt with the heat conduction equation is described in the introduction of the paper. The one-dimensional heat conduction models with using integer- and fractional-order derivatives are listed. Analytical and numerical methods of solution of the heat conduction models with using integer- and fractional-order derivatives are described. Individual methods have been implemented in MATLAB and the examples of simulations are listed. The proposal and experimental verification of the methods for determining thermal diffusivity using half-order derivative of temperature by time are listed at the conclusion of the paper.
Thermal models of electric machines with dynamic workloads
Directory of Open Access Journals (Sweden)
Christian Pohlandt
2015-07-01
Full Text Available Electric powertrains are increasingly used in off-highway machines because of easy controllability and excellent overall efficiency. The main goals are increasing the energy efficiency of the machine and the optimization of the work process. The thermal behaviour of electric machines with dynamic workloads applied to is a key design factor for electric powertrains in off-highway machines. This article introduces a methodology to model the thermal behaviour of electric machines. Using a noncausal modelling approach, an electric powertrain is analysed for dynamic workloads. Cause-effect relationships and reasons for increasing temperature are considered as well as various cooling techniques. The validation of the overall simulation model of the powertrain with measured field data workloads provides convincing results to evaluate numerous applications of electric machines in off-highway machines.
Thermal Model of a Dish Stirling Cavity-Receiver
Directory of Open Access Journals (Sweden)
Rubén Gil
2015-01-01
Full Text Available This paper presents a thermal model for a dish Stirling cavity based on the finite differences method. This model is a theoretical tool to optimize the cavity in terms of thermal efficiency. One of the main outcomes of this work is the evaluation of radiative exchange using the radiosity method; for that purpose, the view factors of all surfaces involved have been accurately calculated. Moreover, this model enables the variation of the cavity and receiver dimensions and the materials to determine the optimal cavity design. The tool has been used to study the cavity optimization regarding geometry parameters and material properties. Receiver absorptivity has been identified as the most influential property of the materials. The optimal aperture height depends on the minimum focal space.
Thermal-capillary model for Czochralski growth of semiconductor materials
Derby, J. J.; Brown, R. A.
1985-01-01
The success of efficiently calculating the temperature field, crystal radius, melt mensicus, and melt/solid interface in the Czochralski crystal growth system by full finite-element solution of the government thermal-capillary model is demonstrated. The model predicts realistic response to changes in pull rate, melt volume, and the thermal field. The experimentally observed phenomena of interface flipping, bumping, and the difficulty maintaining steady-state growth as the melt depth decreases are explained by model results. These calculations will form the basis for the first quantitative picture of Cz crystal growth. The accurate depiction of the melt meniscus is important in calculating the crystal radius and solidification interface. The sensitivity of the results to the equilibrium growth angle place doubt on less sophisticated attempts to model the process without inclusion of the meniscus. Quantitative comparison with experiments should be possible once more representation of the radiation and view factors in the thermal system and the crucible are included. Extensions of the model in these directions are underway.
Quantitative analysis of thermal insulation coatings
DEFF Research Database (Denmark)
Kiil, Søren
2014-01-01
This work concerns the development of simulation tools for mapping of insulation properties of thermal insulation coatings based on selected functional filler materials. A mathematical model, which includes the underlying physics (i.e. thermal conductivity of a heterogeneous two-component coating...... and porosity and thermal conductivity of selected fillers) was recently developed. The model has been validated against data from a previous experimental investigation with hollow glass sphere-based epoxy and acrylic coatings. In this presentation, a concise introduction to the model and some of the simulation...
Thermal modeling of the lithium/polymer battery
Energy Technology Data Exchange (ETDEWEB)
Pals, Carolyn R. [Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering
1994-10-01
Research in the area of advanced batteries for electric-vehicle applications has increased steadily since the 1990 zero-emission-vehicle mandate of the California Air Resources Board. Due to their design flexibility and potentially high energy and power densities, lithium/polymer batteries are an emerging technology for electric-vehicle applications. Thermal modeling of lithium/polymer batteries is particularly important because the transport properties of the system depend exponentially on temperature. Two models have been presented for assessment of the thermal behavior of lithium/polymer batteries. The one-cell model predicts the cell potential, the concentration profiles, and the heat-generation rate during discharge. The cell-stack model predicts temperature profiles and heat transfer limitations of the battery. Due to the variation of ionic conductivity and salt diffusion coefficient with temperature, the performance of the lithium/polymer battery is greatly affected by temperature. Because of this variation, it is important to optimize the cell operating temperature and design a thermal management system for the battery. Since the thermal conductivity of the polymer electrolyte is very low, heat is not easily conducted in the direction perpendicular to cell layers. Temperature profiles in the cells are not as significant as expected because heat-generation rates in warmer areas of the cell stack are lower than heat-generation rates in cooler areas of the stack. This nonuniform heat-generation rate flattens the temperature profile. Temperature profiles as calculated by this model are not as steep as those calculated by previous models that assume a uniform heat-generation rate.
A physical model for measuring thermally-induced block displacements
Bakun-Mazor, Dagan; Feldhiem, Aviran; Keissar, Yuval; Hatzor, Yossef H.
2016-04-01
A new model for thermally-induced block displacement in discontinuous rock slopes has been recently suggested. The model consists of a discrete block that is separated from the rock mass by a tension crack and rests on an inclined plane. The tension crack is filled with a wedge block or rock fragments. Irreversible block sliding is assumed to develop in response to climatic thermal fluctuations and consequent contraction and expansion of the sliding block material. While a tentative analytical solution for this model is already available, we are exploring here the possibility of obtaining such a permanent, thermally-induced, rock block displacement, under fully controlled conditions at the laboratory, and the sensitivity of the mechanism to geometry, mechanical properties, and temperature fluctuations. A large scale concrete physical model (50x150x60 cm^3) is being examined in a Climate-Controlled Room (CCR). The CCR permits accurate control of ambient temperature from 5 to 45 Celsius degrees. The permanent plastic displacement is being measured using four displacement transducers and a high resolution (29M pixel) visual range camera. A series of thermocouples measure the heating front inside the sliding block, hence thermal diffusivity is evaluated from the measured thermal gradient and heat flow. In order to select the appropriate concrete mixture, the mechanical and thermo-physical properties of concrete samples are determined in the lab. Friction angle and shear stiffness of the sliding interface are determined utilizing a hydraulic, servo-controlled direct shear apparatus. Uniaxial compression tests are performed to determine the uniaxial compressive strength, Young's modulus and Poison's ratio of the intact block material using a stiff triaxial load frame. Thermal conductivity and linear thermal expansion coefficient are determined experimentally using a self-constructed measuring system. Due to the fact that this experiment is still in progress, preliminary
Thermal modeling of wide bandgap materials for power MOSFETs
Manandhar, Mahesh B.; Matin, Mohammad A.
2016-09-01
This paper investigates the thermal performance of different wide bandgap (WBG) materials for their applicability as semiconductor material in power electronic devices. In particular, Silicon Carbide (SiC) and Gallium Nitride (GaN) are modeled for this purpose. These WBG materials have been known to show superior intrinsic material properties as compared to Silicon (Si), such as higher carrier mobility, lower electrical and thermal resistance. These unique properties have allowed for them to be used in power devices that can operate at higher voltages, temperatures and switching speeds with higher efficiencies. Digital prototyping of power devices have facilitated inexpensive and flexible methods for faster device development. The commercial simulation software COMSOL Multiphysics was used to simulate a 2-D model of MOSFETs of these WBG materials to observe their thermal performance under different voltage and current operating conditions. COMSOL is a simulation software that can be used to simulate temperature changes due to Joule heating in the case of power MOSFETs. COMSOL uses Finite Element/Volume Analysis methods to solve for variables in complex geometries where multiple material properties and physics are involved. The Semiconductor and Heat Transfer with Solids modules of COMSOL were used to study the thermal performance of the MOSFETs in steady state conditions. The results of the simulations for each of the two WBG materials were compared with that of Silicon to determine relative stability and merit of each material.
Thermal numerical modeling of transmission tower foundations in northern Manitoba
Energy Technology Data Exchange (ETDEWEB)
Kurz, D.; Alfaro, M. [Manitoba Univ., Winnipeg, MB (Canada). Dept. of Civil Engineering; Bannister, K. [Manitoba Hydro, Winnipeg, MB (Canada). Geotechnical Engineering Dept.
2009-07-01
Structural foundations in cold climates must extend below depths of expected frost penetration to protect against frost heaving. The Radisson-Churchill transmission line is the most northern line constructed by Manitoba Hydro. The transmission line crosses areas of both discontinuous and continuous permafrost. This study focused on potential permafrost degradation in the foundations of the power transmission towers. The thermal effectiveness of the foundation design was investigated through numerical modeling of the thermal effects of climate on the transmission tower foundations. The study showed that changing ground cover affects the thermal regime and may cause permafrost degradation. This may lead to reduced bearing capacity for structures, lateral spreading of embankments, and large settlements. Manitoba Hydro successfully used synthetic foundations insulated with polystyrene geofoam for the towers in order to reduce permafrost degradation in the foundations in the warmer southern portions of the transmission line. The geofoam was also used to help prevent frost heaving in the colder northern portions. As part of the thermal monitoring program, ground temperatures were monitored from 1987-1990. Recent studies have improved the understanding of the performance of geofoam insulated foundations. The results from this study will be expanded in future studies to include effects of groundwater and settlements in the development of an elastic thermo-plastic model. 10 refs., 1 tab., 7 figs.
He, Xiaoming; Bhowmick, Sankha; Bischof, John C
2009-07-01
The Arrhenius and thermal isoeffective dose (TID) models are the two most commonly used models for predicting hyperthermic injury. The TID model is essentially derived from the Arrhenius model, but due to a variety of assumptions and simplifications now leads to different predictions, particularly at temperatures higher than 50 degrees C. In the present study, the two models are compared and their appropriateness tested for predicting hyperthermic injury in both the traditional hyperthermia (usually, 43-50 degrees C) and thermal surgery (or thermal therapy/thermal ablation, usually, >50 degrees C) regime. The kinetic parameters of thermal injury in both models were obtained from the literature (or literature data), tabulated, and analyzed for various prostate and kidney systems. It was found that the kinetic parameters vary widely, and were particularly dependent on the cell or tissue type, injury assay used, and the time when the injury assessment was performed. In order to compare the capability of the two models for thermal injury prediction, thermal thresholds for complete killing (i.e., 99% cell or tissue injury) were predicted using the models in two important urologic systems, viz., the benign prostatic hyperplasia tissue and the normal porcine kidney tissue. The predictions of the two models matched well at temperatures below 50 degrees C. At higher temperatures, however, the thermal thresholds predicted using the TID model with a constant R value of 0.5, the value commonly used in the traditional hyperthermia literature, are much lower than those predicted using the Arrhenius model. This suggests that traditional use of the TID model (i.e., R=0.5) is inappropriate for predicting hyperthermic injury in the thermal surgery regime (>50 degrees C). Finally, the time-temperature relationships for complete killing (i.e., 99% injury) were calculated and analyzed using the Arrhenius model for the various prostate and kidney systems.
Modeling of thermal processes in waveguide tracts induction soldering
Murygin, A. V.; Tynchenko, V. S.; Laptenok, V. D.; Emilova, O. A.; Seregin, Yu N.
2017-02-01
The problem solving of the induction heating models development, which describe the heating of the separate structural assembly components of the waveguide path and product generally, is presented in this paper. Proposed mathematical models are based on the thermodynamics equation and on the heat balance law. The system of the heating process mathematical models, such as surge tube and flange heating, and the mathematical model of the energy distribution are presented. During the modeling process with Matlab system by using mathematical models graphs of the tube, flange and coupling heating were obtained. These design charts are confirmed by the results of the experimental study. During the experimental studies pyrometers for temperature control and a video camera for visual control of the process parameters were used. On the basis of obtained models the induction soldering process features analysis is carried out and the need of its automation by the using of the information control systems for thermal management between the connection elements is revealed.
Equilibrium Statistical-Thermal Models in High-Energy Physics
Tawfik, Abdel Nasser
2014-01-01
We review some recent highlights from the applications of statistical-thermal models to different experimental measurements and lattice QCD thermodynamics, that have been made during the last decade. We start with a short review of the historical milestones on the path of constructing statistical-thermal models for heavy-ion physics. We discovered that Heinz Koppe formulated in 1948 an almost complete recipe for the statistical-thermal models. In 1950, Enrico Fermi generalized this statistical approach, in which he started with a general cross-section formula and inserted into it simplifying assumptions about the matrix element of the interaction process that likely reflects many features of the high-energy reactions dominated by density in the phase space of final states. In 1964, Hagedorn systematically analysed the high-energy phenomena using all tools of statistical physics and introduced the concept of limiting temperature based on the statistical bootstrap model. It turns to be quite often that many-par...
Inverse thermal history modelling as a hydrocarbon exploration tool
Energy Technology Data Exchange (ETDEWEB)
Gallagher, K. [Imperial College of Science, Technology and Medicine, London (United Kingdom). TH Huxley School of Environment, Earth Science and Engineering
1998-12-31
Thermal history modelling is a significant part of hydrocarbon exploration and resource assessment. Its primary use is to predict the volume and timing of hydrocarbon generation as a sedimentary basin evolves on timescales of 10{sup 7}-10{sup 8} years. Forward modelling is commonly used to constrain the thermal history in sedimentary basins. Alternatively, inversion schemes may be used which have many advantages over the conventional forward modelling approach. An example of an inversion approach is presented here, wherein the preferred philosophy is to find the least complex model that fits the data. In this case, we estimate a heat flow function (of time) which provides an adequate fit to the available thermal indicator calibration data. The function is also constrained to be smooth, in either a first or second derivative sense. Extra complexity or structure is introduced into the function only where required to fit the data and the regularization stabilizes the inversion. The general formulation is presented and a real data example from the North Slope, Alaska is discussed. (author)
Calibrating thermal erosion models along an Arctic coastline
Wobus, C. W.; Anderson, R. S.; Overeem, I.; Urban, F. E.; Clow, G. D.; Stanton, T. P.
2009-12-01
Coastal erosion rates of 20-30 meters per year have been documented along Alaska’s Beaufort Sea coastline, and a number of studies suggest that erosion rates have accelerated as a result of climate change. However, a lack of direct observational evidence has limited our progress in quantifying the role of climate change on coastal erosion rates in the Arctic. In particular, while longer ice-free periods are likely to lead to both warmer surface waters and longer fetch, the relative roles of thermal and mechanical (wave) erosion in driving coastal retreat have not been comprehensively quantified. We focus on the potential magnitude of thermal erosion along a permafrost coastline in the northern National Petroleum Reserve-Alaska (NPR-A), where erosion rates have averaged 10-15 meters/year over two years of direct monitoring. We take advantage of these extraordinary rates of coastal erosion to directly observe erosion processes via time-lapse photography, while monitoring temperature, solar radiation and wind speed at the same time. These combined observations are used to calibrate models of thermal erosion. Our observations suggest that virtually all of the erosion in this setting can be explained as a purely thermal process. Coastal bluffs are first notched and then topple into the ocean, failing dominantly along ice wedges that serve as planes of weakness. Furthermore, the high ice content and the fine grain size of the coastal plain materials that comprise the bluffs appear to limit any strong negative feedback on erosion rates, since the sediments are readily dispersed on the shallow shelf. Although erosion driven purely by thermal processes may be unique to this particular coastal zone, these observations implicate a direct relationship between climatic warming and landscape change. Erosion of sandy coastlines in other parts of the NPR-A may also be ultimately controlled by thermal energy, once a thin veneer of clastic material is removed by wave action from
Numerical Modeling of Thermal Pollution of Large Water Bodies from Thermal and Nuclear Power Plants
Lyubimova, Tatyana; Lepikhin, Anatoly; Lyakhin, Yury; Parshakova, Yanina; Tiunov, Alexey
2016-04-01
Currently, the major manufacturers of electrical energy are the thermal and nuclear power plants including the cooling ponds in the processing chains. For a wide range of both environmental and technological problems, the evaluation of the temperature fields in the cooling ponds at certain critical values of hydrological and meteorological parameters is important. The present paper deals with the evaluation of the thermal effect of one of the largest thermal power plant in Europe - Perm GRES - to its cooling pond which is the Kama Reservoir. Since the area of the possible impact is rather large and the reservoir itself is characterized by a very complex morphometry, numerical modeling of thermal spot propagation in the Kama River due to the discharge of warm water by Perm GRES for the entire area in the 3D-formulation with the desired detail setting morphometric characteristics of the water body meets very serious difficulties. Because of that, to solve the problem, a combined scheme of calculations based on the combination of hydrodynamic models in 2D and 3D formulations was used. At the first stage of the combined scheme implementation, 2D hydrodynamical model was developed for all possible area, using software SMS v.11.1. The boundary and initial conditions for this model were formulated on the basis of calculations made using 1D hydrodynamical model developed and applied for the entire Kama Reservoir. Application of 2D hydrodynamical model for solving the problem under consideration was needed to obtain the necessary information for setting the boundary conditions for the 3D model. Software package ANSYS Fluent v.6.3 was used for the realization of 3D model. 3D modeling was performed for different wind speeds and directions and quantitative characteristics of the discharge of warm water. To verify the models, the data of the detailed field measurements in the zones of thermal pollution of the Kama reservoir due to impact of the Perm GRES were used. A
Transient electro-thermal modeling of bipolar power semiconductor devices
Gachovska, Tanya Kirilova; Du, Bin
2013-01-01
This book presents physics-based electro-thermal models of bipolar power semiconductor devices including their packages, and describes their implementation in MATLAB and Simulink. It is a continuation of our first book Modeling of Bipolar Power Semiconductor Devices. The device electrical models are developed by subdividing the devices into different regions and the operations in each region, along with the interactions at the interfaces, are analyzed using the basic semiconductor physics equations that govern device behavior. The Fourier series solution is used to solve the ambipolar diffusio
Model for continuous thermal metal to insulator transition
Jian, Chao-Ming; Bi, Zhen; Xu, Cenke
2017-09-01
We propose a d -dimensional interacting Majorana fermion model with quenched disorder, which gives us a continuous quantum phase transition between a diffusive thermal metal phase with a finite entropy density to an insulator phase with zero entropy density. This model is based on coupled Sachdev-Ye-Kitaev model clusters, and hence has a controlled large-N limit. The metal-insulator transition is accompanied by a spontaneous time-reversal symmetry breaking. We perform controlled calculations to show that the energy diffusion constant jumps to zero discontinuously at the metal-insulator transition, while the time-reversal symmetry-breaking order parameter increases continuously.
A Temperature-Dependent Thermal Model of IGBT Modules Suitable for Circuit-Level Simulations
DEFF Research Database (Denmark)
Wu, Rui; Wang, Huai; Ma, Ke
2014-01-01
Thermal impedance of IGBT modules may vary with operating conditions due to that the thermal conductivity and heat capacity of materials are temperature dependent. This paper proposes a Cauer thermal model for a 1700 V/1000 A IGBT module with temperature-dependent thermal resistances and thermal ...... relevant reliability aspect performance. A test bench is built up with an ultra-fast infrared (IR) camera to validate the proposed thermal impedance model.......Thermal impedance of IGBT modules may vary with operating conditions due to that the thermal conductivity and heat capacity of materials are temperature dependent. This paper proposes a Cauer thermal model for a 1700 V/1000 A IGBT module with temperature-dependent thermal resistances and thermal...
Geotail observations of temperature anisotropy of the two-component protons in the dusk plasma sheet
Directory of Open Access Journals (Sweden)
M. N. Nishino
2007-03-01
Full Text Available In search for clues towards the understanding of the cold plasma sheet formation under northward IMF, we study the temperature anisotropy of the two-component protons in the plasma sheet near the dusk low-latitude boundary observed by the Geotail spacecraft. The two-component protons result from mixing of the cold component from the solar wind and the hot component of the magnetospheric origin, and may be the most eloquent evidence for the transport process across the magnetopause. The cold component occasionally has a strong anisotropy in the dusk flank, and the sense of the anisotropy depends on the observed locations: the parallel temperature is enhanced in the tail flank while the perpendicular temperature is enhanced on the dayside. The hot component is nearly isotropic in the tail while the perpendicular temperature is enhanced on the dayside. We discuss possible mechanism that can lead to the observed temperature anisotropies.
Peng, Daoling; Weigend, Florian; Reiher, Markus
2013-01-01
We present an efficient algorithm for one- and two-component relativistic exact-decoupling calculations. The spin-orbit coupling was taken into account for the evaluation of relativistically transformed Hamiltonian. The relativistic decoupling transformation has to be evaluated with primitive functions so that the construction of the relativistic one-electron Hamiltonian becomes the bottleneck of the whole calculation for large molecules. We apply our recently developed local DLU scheme [J. Chem. Phys. 136 (2012) 244108] to accelerate this step. With our new implementation two-component relativistic density functional calculations can be performed invoking the resolution-of-identity density-fitting approximation and (Abelian as well as non-Abelian) point group symmetries to accelerate both the exact-decoupling and the two-electron part. The capability of our implementation is illustrated at the example of silver clusters with up to 309 atoms, for which the cohesive energy is calculated and extrapolated to the...
Use of two-component signal transduction systems in the construction of synthetic genetic networks.
Ninfa, Alexander J
2010-04-01
Two-component signal transduction systems are a common type of signaling system in prokaryotes; the typical cell has dozens of systems regulating aspects of physiology and controlling responses to environmental conditions. In this review, I consider how these systems may be useful for engineering novel cell functions. Examples of successful incorporation of two-component systems into engineered systems are noted, and features of the systems that favor or hinder potential future use of these signaling systems for synthetic biology applications are discussed. The focus will be on the engineering of novel couplings of sensory functions to signaling outputs. Recent successes in this area are noted, such as the development of light-sensitive transmitter proteins and chemotactic receptors responsive to nitrate. Copyright 2010 Elsevier Ltd. All rights reserved.
Lou, Qiang; Qi, Yijun; Ma, Yuanfang; Qu, Di
2014-01-01
Staphylococcus epidermidis, which is a causative pathogen of nosocomial infection, expresses its virulent traits such as biofilm and autolysis regulated by two-component signal transduction system SaeRS. In this study, we performed a proteomic analysis of differences in expression between the S. epidermidis 1457 wild-type and saeRS mutant to identify candidates regulated by saeRS using two-dimensional gel electrophoresis (2-DE) combined with matrix-assisted laser desorption/lonization mass spectrometry (MALDI-TOF-MS). Of 55 identified proteins that significantly differed in expression between the two strains, 15 were upregulated and 40 were downregulated. The downregulated proteins included enzymes related to glycolysis and TCA cycle, suggesting that glucose is not properly utilized in S. epidermidis when saeRS was deleted. The study will be helpful for treatment of S. epidermidis infection from the viewpoint of metabolic modulation dependent on two-component signal transduction system SaeRS.
Atomic Tunneling Effect in Two-Component Bose-Einstein Condensates with a Coupling Drive
Institute of Scientific and Technical Information of China (English)
JIAOZhi-Yong; YUZhao-Xian; YANGXin-Jian
2004-01-01
In this paper, we have studied the atomic population difference and the atomic tunneling current of two-component Bose-Einstein condensates with a coupling drive. It is found that when the two-component Bose Einstein condensates are initially in the coherent states, the atomic population difference may exhibit the step structure, in which the numbers of the step increase with the decrease of the Rabi frequency and with the increment of the initial phase difference. The atomic population difference may exhibit collapses, and revivals, in which their periods are affected dramatically by the Rabi frequency and the initial phase difference. The atomic tunneling current may exhibit damping oscillation behaviors, and exist the step structure for the time range of 10-10 ～ 10-9 second.
Engineering bacterial two-component system PmrA/PmrB to sense lanthanide ions.
Liang, Haihua; Deng, Xin; Bosscher, Mike; Ji, Quanjiang; Jensen, Mark P; He, Chuan
2013-02-13
The Salmonella PmrA/PmrB two-component system uses an iron(III)-binding motif on the cell surface to sense the environmental or host ferric level and regulate PmrA-controlled gene expression. We replaced the iron(III)-binding motif with a lanthanide-binding peptide sequence that is known to selectively recognize trivalent lanthanide ions. The newly engineered two-component system (PmrA/PmrB) can effectively sense lanthanide ion and regulate gene expression in E. coli . This work not only provides the first known lanthanide-based sensing and response in live cells but also demonstrates that the PmrA/PmrB system is a suitable template for future synthetic biology efforts to construct bacteria that can sense and respond to other metal ions in remediation or sequestration.
Energy Technology Data Exchange (ETDEWEB)
Xu, Fei [Key Laboratory of Fiber Optic Sensing Technology and Information Processing, Ministry of Education, Wuhan University of Technology, Wuhan 430070 (China); Huang, Jiahao, E-mail: hjiahao@mail2.sysu.edu.cn [TianQin Research Center & School of Physics and Astronomy, Sun Yat-Sen University, SYSU Zhuhai Campus, Zhuhai 519082 (China); Liu, Quan [Key Laboratory of Fiber Optic Sensing Technology and Information Processing, Ministry of Education, Wuhan University of Technology, Wuhan 430070 (China)
2017-03-03
Highlights: • A scheme for detecting magnetic field gradients via a double-well two-component Bose–Einstein condensate interferometer. • The magnetic field gradient can be extracted by either the spin population or the external state. • Our proposal is potentially sensitive to weak magnetic field inhomogeneity due to its small sensor size. - Abstract: We have proposed a scheme to detect magnetic field gradients via an interferometer based on a double-well two-component Bose–Einstein condensate (BEC). Utilizing a sequence of quantum control operations on both external and internal degree of the BEC, one can extract the magnetic field gradients by measuring either the population in one component or the fidelity between the final external state and the initial ground state. Our scheme can be implemented by current experimental techniques of manipulating ultracold atoms.
Analytical Model for Ring Heater Thermal Compensation in Advanced LIGO
Ramette, Joshua; Brooks, Aidan; Blair, Carl; Wang, Haoyu; Heintze, Matthew
2015-01-01
Advanced laser interferometer gravitational-wave detectors use high laser power to achieve design sensitivity. A small part of this power is absorbed in the interferometer cavity mirrors where it creates thermal lenses, causing aberrations in the main laser beam that must be minimized by the actuation of "ring heaters," additional heater elements that are aimed to reduce the temperature gradients in the mirrors. In this article we derive the first analytical model of the temperature field generated by an ideal ring heater. We express the resulting optical aberration contribution to the main laser beam in this axisymmetric case. Used in conjunction with wavefront measurements, our model provides a more complete understanding of the thermal state of the cavity mirrors and will allow a more efficient use of the ring heaters in Advanced LIGO.
Thermal Model Description of Collisions of Small Nuclei
Cleymans, J.; Oeschler, H.; Redlich, K.; Sharma, N.
2016-01-01
The dependence of particle production on the size of the colliding nuclei is analyzed in terms of the thermal model using the canonical ensemble. The concept of strangeness correlation in clusters of sub-volume $V_c$ is used to account for the suppression of strangeness. A systematic analysis is presented of the predictions of the thermal model for particle production in collisions of small nuclei. The pattern of the maxima in particle ratios of strange particles to pions as a function of beam energy is quite special, as they do not occur at the same beam energy and are sensitive to system size. In particular, the $\\Lambda/\\pi^+$ ratio shows a clear maximum even for the smallest systems while the maximum in the K$^+/\\pi^+$ ratio disappears in small systems.
Modeling of thermal conductivity of stainless-steelmaking dust pellets
Institute of Scientific and Technical Information of China (English)
彭兵; 彭及; 余笛
2004-01-01
The thermal conductivity of stainless-steelmaking dust pellets, an important parameter for the direct recycling of the dust, is naturally of interest to metallurgists. The measurement of central temperature and surface temperature was taken in a furnace. The physical model and calculation model for the heating process were set up to check the thermal conductivity of the dust pellets. The physical structure parameters δ and λ of the basic unit are 0.92 and 0.45 based on the calculation. The temperature in the pellet can be expressed in a linear equation a5 Tp =a1 TN +a2 TM +a4. This is convenient to determine the central temperature of a pellet in the direct recycling process.
A new model for analysing thermal stress in granular composite
Institute of Scientific and Technical Information of China (English)
郑茂盛; 金志浩; 浩宏奇
1995-01-01
A double embedding model of inletting reinforcement grain and hollow matrix ball into the effective media of the particulate-reinforced composite is advanced. And with this model the distributions of thermal stress in different phases of the composite during cooling are studied. Various expressions for predicting elastic and elastoplastic thermal stresses are derived. It is found that the reinforcement suffers compressive hydrostatic stress and the hydrostatic stress in matrix zone is a tensile one when temperature decreases; when temperature further decreases, yield area in matrix forms; when the volume fraction of reinforcement is enlarged, compressive stress on grain and tensile hydrostatic stress in matrix zone decrease; the initial temperature difference of the interface of reinforcement and matrix yielding rises, while that for the matrix yielding overall decreases.
Software for Automated Generation of Reduced Thermal Models for Spacecraft Thermal Control Project
National Aeronautics and Space Administration — Thermal analysis is increasingly used in thermal engineering of spacecrafts in every stage, including design, test, and ground-operation simulation. Current...
Electric mine motor thermal models aiding design and setting thermal protections
National Research Council Canada - National Science Library
Krok, R
2012-01-01
The paper presents original modified thermal networks for calculations of the temperature field in induction mine motors under steady and transient conditions aiding design and setting thermal protections...
Power Loss Calculation and Thermal Modelling for a Three Phase Inverter Drive System
Directory of Open Access Journals (Sweden)
Z. Zhou
2005-12-01
Full Text Available Power losses calculation and thermal modelling for a three-phase inverter power system is presented in this paper. Aiming a long real time thermal simulation, an accurate average power losses calculation based on PWM reconstruction technique is proposed. For carrying out the thermal simulation, a compact thermal model for a three-phase inverter power module is built. The thermal interference of adjacent heat sources is analysed using 3D thermal simulation. The proposed model can provide accurate power losses with a large simulation time-step and suitable for a long real time thermal simulation for a three phase inverter drive system for hybrid vehicle applications.
Kinetics and mechanism of the oxidation process of two-component Fe-Al alloys
Przewlocka, H.; Siedlecka, J.
1982-01-01
The oxidation process of two-component Fe-Al alloys containing up to 7.2% Al and from 18 to 30% Al was studied. Kinetic measurements were conducted using the isothermal gravimetric method in the range of 1073-1223 K and 1073-1373 K for 50 hours. The methods used in studies of the mechanism of oxidation included: X-ray microanalysis, X-ray structural analysis, metallographic analysis and marker tests.
In vivo study of the two-component signaling network in Escherichia coli
Sommer, Erik
2012-01-01
Microorganisms commonly use ‘two-component’ signaling systems for sensing environmental conditions, with members being present in nearly all bacterial and archaeal genomes in different numbers. Prototypical two-component systems are comprised of a sensory histidine kinase and a response regulator protein that is phosphorylated by the kinase. The regulator typically acts as a transcription factor regulating gene expression. Due to their prevalence in microorganisms, a basic understanding of th...
Directory of Open Access Journals (Sweden)
Christian H Bell
2010-02-01
Full Text Available Two-component signal transduction pathways comprising histidine protein kinases (HPKs and their response regulators (RRs are widely used to control bacterial responses to environmental challenges. Some bacteria have over 150 different two-component pathways, and the specificity of the phosphotransfer reactions within these systems is tightly controlled to prevent unwanted crosstalk. One of the best understood two-component signalling pathways is the chemotaxis pathway. Here, we present the 1.40 A crystal structure of the histidine-containing phosphotransfer domain of the chemotaxis HPK, CheA(3, in complex with its cognate RR, CheY(6. A methionine finger on CheY(6 that nestles in a hydrophobic pocket in CheA(3 was shown to be important for the interaction and was found to only occur in the cognate RRs of CheA(3, CheY(6, and CheB(2. Site-directed mutagenesis of this methionine in combination with two adjacent residues abolished binding, as shown by surface plasmon resonance studies, and phosphotransfer from CheA(3-P to CheY(6. Introduction of this methionine and an adjacent alanine residue into a range of noncognate CheYs, dramatically changed their specificity, allowing protein interaction and rapid phosphotransfer from CheA(3-P. The structure presented here has allowed us to identify specificity determinants for the CheA-CheY interaction and subsequently to successfully reengineer phosphotransfer signalling. In summary, our results provide valuable insight into how cells mediate specificity in one of the most abundant signalling pathways in biology, two-component signal transduction.
General aspects of two-component regulatory circuits in bacteria: Domains, signals and roles.
Padilla-Vaca, Felipe; Mondragón-Jaimes, Verónica; Franco, Bernardo
2016-08-09
All living organisms are subject to changing environments, which must be sensed in order to respond swiftly and efficiently. Two-component systems (TCS) are signal transduction regulatory circuits based typically on a membrane bound sensor kinase and a cytoplasmic response regulator, that is activated through a histidine to aspartate phosphorelay reactions. Activated response regulator acts usually as a transcription factor. The best known examples were identified in bacteria, but they are also found in fungi, algae and plants. Thus far, they are not found in mammals. Regulatory circuits coupled to two-component systems exhibit a myriad of responses to environmental stimuli such as: redox potential, pH, specific metabolites, pressure, light and more recently to specific antimicrobial peptides that activate a sensor kinase responsible for expressing virulence factors through the active response regulator. In this review we explore general aspects on two-component systems that ultimately can play a role on virulence regulation, also the intriguing domain properties of the sensor kinases that can be a potential target for antimicrobial compounds. Only a handful of sensor kinases are extensively characterized, the vast majority belong to what we call 'the dark matter of bacterial signal transduction' since no known signal, structure and biochemical properties are available. Regulatory circuits from vertebrate pathogenic organisms can explain virulence in terms of either response to environmental factors or specific niche occupancy. Hopefully, knowledge on these signal transduction systems can lead to identify novel molecules that target two-component systems, since the increase of drug resistant microorganisms is worrisome.
Institute of Scientific and Technical Information of China (English)
Zhang Xiao-Fei; Zhang Pei; He Wan-Quan; Liu Xun-Xu
2011-01-01
By using a unified theory of the formation of various types of vector-solitons in two-component Bose-Einstein condensates with tunable interactions, we obtain a family of exact vector-soliton solutions for the coupled nonlinear Schr(o)dinger equations. Moreover, the Bogoliubov equation shows that there exists stable dark soliton in specific situations. Our results open up new ways in considerable experimental interest for the quantum control of multi-component Bose-Einstein condensates.
Bloch Oscillations of Two-Component Bose-Einstein Condensates in Optical Lattices
Institute of Scientific and Technical Information of China (English)
GU Huai-Qiang; WANG Zhi-Cheng; JIN Kang; TAN Lei
2006-01-01
@@ We study the Bloch oscillations of two-component Bose-Einstein condensates trapped in spin-dependent optical lattices. The influence of the intercomponent atom interaction on the system is discussed in detail Accelerated breakdown of the Bloch oscillations and revival phenomena are found respectively for the repulsive and attractive case. For both the cases, the system will finally be set in a quantum self-trapping state due to dynamical instability.
Beausoleil, R G; Kells, W; Camp, J; Gustafson, E K; Fejer, M M
2002-01-01
We develop a steady-state analytical and numerical model of the optical response of power-recycled Fabry-Perot Michelson laser gravitational-wave detectors to thermal focusing in optical substrates. We assume that the thermal distortions are small enough that we can represent the unperturbed intracavity field anywhere in the detector as a linear combination of basis functions related to the eigenmodes of one of the Fabry-Perot arm cavities, and we take great care to preserve numerically the nearly ideal longitudinal phase resonance conditions that would otherwise be provided by an external servo-locking control system. We have included the effects of nonlinear thermal focusing due to power absorption in both the substrates and coatings of the mirrors and beamsplitter, the effects of a finite mismatch between the curvatures of the laser wavefront and the mirror surface, and the diffraction by the mirror aperture at each instance of reflection and transmission. We demonstrate a detailed numerical example of thi...
Thermal performance modeling of cross-flow heat exchangers
Cabezas-Gómez, Luben; Saíz-Jabardo, José Maria
2014-01-01
This monograph introduces a numerical computational methodology for thermal performance modeling of cross-flow heat exchangers, with applications in chemical, refrigeration and automobile industries. This methodology allows obtaining effectiveness-number of transfer units (e-NTU) data and has been used for simulating several standard and complex flow arrangements configurations of cross-flow heat exchangers. Simulated results have been validated through comparisons with results from available exact and approximate analytical solutions. Very accurate results have been obtained over wide ranges
Modeling Interfacial Thermal Boundary Conductance of Engineered Interfaces
2014-08-31
involving carbon materials. Determined scaling laws for conductivity of carbon nanotube networks [11]. Modified the DMM to predict hBD at metal–graphite...111, 084310 (2012). 11A. N. Volkov and L. V. Zhigilei, “Scaling laws and mesoscopic modeling of thermal conductivity in carbon nanotube materials...instead from an algebraic expression that accurately reproduces the MD results but with negligible computational expense. This permitted a large
Numerical and Experimental Models of the Thermally Stratified Boundary Layer
Directory of Open Access Journals (Sweden)
Michalcová Vladimíra
2016-12-01
Full Text Available The article describes a change of selected turbulent variables in the surroundings of a flow around thermally loaded object. The problem is solved numerically in the software Ansys Fluent using a Transition SST model that is able to take into account the difference between high and low turbulence at the interface between the wake behind an obstacle and the free stream. The results are verified with experimental measurements in the wind tunnel.
Black hole thermalization rate from brane anti-brane model
Lifschytz, G
2004-01-01
We develop the quasi-particle picture for Schwarzchild and far from extremal black holes. We show that the thermalization equations of the black hole is recovered from the model of branes and anti-branes. This can also be viewed as a field theory explanation of the relationship between area and entropy for these black holes. As a by product the annihilation rate of branes and anti-branes is computed.
Black hole thermalization rate from brane anti-brane model
Energy Technology Data Exchange (ETDEWEB)
Lifschytz, Gilad E-mail: giladl@research.haifa.ac.il
2004-08-01
We develop the quasi-particle picture for Schwarzchild and far from extremal black holes. We show that the thermalization equations of the black hole is recovered from the model of branes and anti-branes. This can also be viewed as a field theory explanation of the relationship between area and entropy for these black holes. As a by product the annihilation rate of branes and anti-branes is computed. (author)
Modeling Pumped Thermal Energy Storage with Waste Heat Harvesting
Abarr, Miles L. Lindsey
This work introduces a new concept for a utility scale combined energy storage and generation system. The proposed design utilizes a pumped thermal energy storage (PTES) system, which also utilizes waste heat leaving a natural gas peaker plant. This system creates a low cost utility-scale energy storage system by leveraging this dual-functionality. This dissertation first presents a review of previous work in PTES as well as the details of the proposed integrated bottoming and energy storage system. A time-domain system model was developed in Mathworks R2016a Simscape and Simulink software to analyze this system. Validation of both the fluid state model and the thermal energy storage model are provided. The experimental results showed the average error in cumulative fluid energy between simulation and measurement was +/- 0.3% per hour. Comparison to a Finite Element Analysis (FEA) model showed energy of a recently proposed Pumped Thermal Energy Storage and Bottoming System (Bot-PTES) that uses ammonia as the working fluid. This analysis focused on the effects of hot thermal storage utilization, system pressure, and evaporator/condenser size on the system performance. This work presents the estimated performance for a proposed baseline Bot-PTES. Results of this analysis showed that all selected parameters had significant effects on efficiency, with the evaporator/condenser size having the largest effect over the selected ranges. Results for the baseline case showed stand-alone energy storage efficiencies between 51 and 66% for varying power levels and charge states, and a stand-alone bottoming efficiency of 24%. The resulting efficiencies for this case were low compared to competing technologies; however, the dual-functionality of the Bot-PTES enables it to have higher capacity factor, leading to 91-197/MWh levelized cost of energy compared to 262-284/MWh for batteries and $172-254/MWh for Compressed Air Energy Storage.
Electroweak absolute, meta-, and thermal stability in neutrino mass models
Lindner, Manfred; Patel, Hiren H.; Radovčić, Branimir
2016-04-01
We analyze the stability of the electroweak vacuum in neutrino mass models containing right-handed neutrinos or fermionic isotriplets. In addition to considering absolute stability, we place limits on the Yukawa couplings of new fermions based on metastability and thermal stability in the early Universe. Our results reveal that the upper limits on the neutrino Yukawa couplings can change significantly when the top quark mass is allowed to vary within the experimental range of uncertainty in its determination.
Electroweak Absolute, Meta-, and Thermal Stability in Neutrino Mass Models
Lindner, Manfred; Radovčić, Branimir
2015-01-01
We analyze the stability of the electroweak vacuum in neutrino mass models containing right handed neutrinos or fermionic isotriplets. In addition to considering absolute stability, we place limits on the Yukawa couplings of new fermions based on metastability and thermal stability in the early Universe. Our results reveal that the upper limits on the neutrino Yukawa couplings can change significantly when the top quark mass is allowed to vary within the experimental range of uncertainty in its determination.
Thermal model of local ultrasound heating of biological tissue
Nedogovor, V. A.; Sigal, V. L.; Popsuev, E. I.
1996-09-01
Possibilities of creation of controlled temperature fields in deep-seated biological tissue with the use of an endocavity ultrasound applicator with surface cooling are considered. Mathematical models are proposed and calculated that make it possible to construct acoustic and thermal fields in biotissues depending on the thermophysical and ultrasound characteristics of the medium being irradiated and to reveal situations and effects that are important for solving problems of practical medicine in the field of local ultrasound hyperthermia and thermotherapy of tissue.
Collisions of Small Nuclei in the Thermal Model
Cleymans, J; Oeschler, H.; Redlich, K.; Sharma, N.
2016-01-01
An analysis is presented of the expectations of the thermal model for particle production in collisions of small nuclei. The maxima observed in particle ratios of strange particles to pions as a function of beam energy in heavy ion collisions, are reduced when considering smaller nuclei. Of particular interest is the $\\Lambda/\\pi^+$ ratio shows the strongest maximum which survives even in collisions of small nuclei.
The analysis of thermal-hydraulic models in MELCOR code
Energy Technology Data Exchange (ETDEWEB)
Kim, M. H.; Hur, C.; Kim, D. K.; Cho, H. J. [POhang Univ., of Science and TECHnology, Pohang (Korea, Republic of)
1996-07-15
The objective of the present work is to verify the prediction and analysis capability of MELCOR code about the progression of severe accidents in light water reactor and also to evaluate appropriateness of thermal-hydraulic models used in MELCOR code. Comparing the results of experiment and calculation with MELCOR code is carried out to achieve the above objective. Specially, the comparison between the CORA-13 experiment and the MELCOR code calculation was performed.
Structural, thermal, optical and gravitational modelling for LISA
Energy Technology Data Exchange (ETDEWEB)
Merkowitz, Stephen M [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Conkey, Shelly [Swales Aerospace, 5050 Powder Mill Rd, Beltsville, MD 20705 (United States); Haile, William B [Swales Aerospace, 5050 Powder Mill Rd, Beltsville, MD 20705 (United States); KellyIII, William R [Swales Aerospace, 5050 Powder Mill Rd, Beltsville, MD 20705 (United States); Peabody, Hume [Swales Aerospace, 5050 Powder Mill Rd, Beltsville, MD 20705 (United States); Dumont, Philip J [Jet Propulsion Laboratory, Pasadena, CA 91109 (United States)
2004-03-07
The laser interferometer space antenna (LISA) mission uses laser interferometry to detect and observe gravitational waves from astrophysical sources. Modelling of LISA ultimately needs to forecast and interrelate the behaviour of the science input, structure, optics, control systems and many other factors that affect the performance of the flight hardware. These models include high precision STOP (structural-thermal-optical) analyses. In addition, self-gravity analyses of the spacecraft, based on the structural-thermal modelling results, are required for each analysis cycle to understand the gravitational interaction between the spacecraft components. The complete analysis cycle is called STOP-G. Several aspects of this analysis require unprecedented precision due to LISA's challenging design requirements. We present here a modelling approach designed to minimize analysis errors, particularly those that enter when mapping results from one modelling step to the next. Central to the approach is the use of a single model topology for all phases of the STOP-G analysis cycle. The feasibility of this approach was verified using a simplified model of the LISA spacecraft.
Different electronic charges in two-component superconductor by coherent state
Energy Technology Data Exchange (ETDEWEB)
Shi, Xuguang, E-mail: shixg@bjfu.edu.cn
2015-07-17
Recently, the different electronic charges, which are related to the different coupling constants with magnetic field, in the two-component superconductor have been studied in the frame of Ginzburg–Landau theory. In order to study the electronic charges in detail we suggest the wave function in the two-component superconductor to be in the coherent state. We find the different electronic charges exist not only in the coherent state but also in the incoherent state. But the ratio of the different charges in the coherent state is different from the ratio in the incoherence. The expressions of the coupling constants are given directly based on the coherence effects. We also discuss the winding number in such a system. - Highlights: • Suggest the wave function in two-component superconductor is coherent. • Interpret the existence of different electric charges by the coherent states. • Derive a new expression for the supercurrent. • Reveal the relation between different electric charges and winding number.
Indian Academy of Sciences (India)
K V Srividhya; S Krishnaswamy
2007-08-01
Bacteriophage induced lysis of host bacterial cell is mediated by a two component cell lysis cassette comprised of holin and lysozyme. Prophages are integrated forms of bacteriophages in bacterial genomes providing a repertoire for bacterial evolution. Analysis using the prophage database (http://bicmku.in:8082) constructed by us showed 47 prophages were associated with putative two component cell lysis genes. These proteins cluster into four different subgroups. In this process, a putative holin (essd) and endolysin (ybcS), encoded by the defective lambdoid prophage DLP12 was found to be similar to two component cell lysis genes in functional bacteriophages like p21 and P1. The holin essd was found to have a characteristic dual start motif with two transmembrane regions and C-terminal charged residues as in class II holins. Expression of a fusion construct of essd in Escherichia coli showed slow growth. However, under appropriate conditions, this protein could be over expressed and purified for structure function studies. The second component of the cell lysis cassette, ybcS, was found to have an N-terminal SAR (Signal Arrest Release) transmembrane domain. The construct of ybcS has been over expressed in E. coli and the purified protein was functional, exhibiting lytic activity against E. coli and Salmonella typhi cell wall substrate. Such targeted sequence-structure-function characterization of proteins encoded by cryptic prophages will help understand the contribution of prophage proteins to bacterial evolution.
Design of Novel Mixer and Applicator for Two-Component Surgical Adhesives
Go, Kevin; Kim, Yeong; Lee, Andy H.; Staricha, Kelly; Messersmith, Phillip; Glucksberg, Matthew
2015-01-01
Current mixer and applicator devices on the market are not able to properly and efficiently mix two-component surgical adhesives in small volumes necessary to achieve economic viability. Furthermore, in these devices a significant amount of adhesive is wasted during the application process, as material within the dead space of the mixing chamber must be discarded. We have designed and demonstrated a new active mixer and applicator system capable of rapidly and efficiently mixing two components of an adhesive and applying it to the surgical site. Recently, Messersmith et al. have developed a tissue adhesive inspired by the mussel byssus and have shown that it is effective as a surgical sealant, and is especially suited for wet environments such as in fetal surgery. Like some other tissue sealants, this one requires that two components of differing viscosities be thoroughly mixed within a specified and short time period. Through a combination of compression and shear testing, we demonstrated that our device could effectively mix the adhesive developed by Messersmith et al. and improve its shear strength to significantly higher values than what has been reported for vortex mixing. Overall, our mixer and applicator system not only has potential applications in mixing and applying various adhesives in multiple surgical fields but also makes this particular adhesive viable for clinical use. PMID:26421090
Real time propagation of the exact two component time-dependent density functional theory
Goings, Joshua J.; Kasper, Joseph M.; Egidi, Franco; Sun, Shichao; Li, Xiaosong
2016-09-01
We report the development of a real time propagation method for solving the time-dependent relativistic exact two-component density functional theory equations (RT-X2C-TDDFT). The method is fundamentally non-perturbative and may be employed to study nonlinear responses for heavy elements which require a relativistic Hamiltonian. We apply the method to several group 12 atoms as well as heavy-element hydrides, comparing with the extensive theoretical and experimental studies on this system, which demonstrates the correctness of our approach. Because the exact two-component Hamiltonian contains spin-orbit operators, the method is able to describe the non-zero transition moment of otherwise spin-forbidden processes in non-relativistic theory. Furthermore, the two-component approach is more cost effective than the full four-component approach, with similar accuracy. The RT-X2C-TDDFT will be useful in future studies of systems containing heavy elements interacting with strong external fields.
Thermal network model of a passive solar house
Energy Technology Data Exchange (ETDEWEB)
Carroll, J.A.; Clinton, J.R.
1980-01-01
A 35-node thermal network simulation model used at UCSD for modelling houses containing several passive or hybrid features is described. To avoid biases associated with use of a room node, radiative and convective heat exchanges between components are modelled separately. Run costs are under $1 for a 7-month heating season. The house modelled is a wood frame building with slab floor. Windows on all building faces can be modelled. The Trombe wall can be vented to the interior or to an under-floor rockbed. The rockbed model provides for controlled smearing of thermoclines during both flow and no-flow conditions. Controls include shading and night insulation, venting, thermostat setbacks, off-peak backup, and various rockbed controls.
Thermal Modeling Method Improvements for SAGE III on ISS
Liles, Kaitlin; Amundsen, Ruth; Davis, Warren; McLeod, Shawn
2015-01-01
The Stratospheric Aerosol and Gas Experiment III (SAGE III) instrument is the fifth in a series of instruments developed for monitoring aerosols and gaseous constituents in the stratosphere and troposphere. SAGE III will be delivered to the International Space Station (ISS) via the SpaceX Dragon vehicle. A detailed thermal model of the SAGE III payload, which consists of multiple subsystems, has been developed in Thermal Desktop (TD). Many innovative analysis methods have been used in developing this model; these will be described in the paper. This paper builds on a paper presented at TFAWS 2013, which described some of the initial developments of efficient methods for SAGE III. The current paper describes additional improvements that have been made since that time. To expedite the correlation of the model to thermal vacuum (TVAC) testing, the chambers and GSE for both TVAC chambers at Langley used to test the payload were incorporated within the thermal model. This allowed the runs of TVAC predictions and correlations to be run within the flight model, thus eliminating the need for separate models for TVAC. In one TVAC test, radiant lamps were used which necessitated shooting rays from the lamps, and running in both solar and IR wavebands. A new Dragon model was incorporated which entailed a change in orientation; that change was made using an assembly, so that any potential additional new Dragon orbits could be added in the future without modification of the model. The Earth orbit parameters such as albedo and Earth infrared flux were incorporated as time-varying values that change over the course of the orbit; despite being required in one of the ISS documents, this had not been done before by any previous payload. All parameters such as initial temperature, heater voltage, and location of the payload are defined based on the case definition. For one component, testing was performed in both air and vacuum; incorporating the air convection in a submodel that was
Improvements to Wire Bundle Thermal Modeling for Ampacity Determination
Rickman, Steve L.; Iannello, Christopher J.; Shariff, Khadijah
2017-01-01
Determining current carrying capacity (ampacity) of wire bundles in aerospace vehicles is critical not only to safety but also to efficient design. Published standards provide guidance on determining wire bundle ampacity but offer little flexibility for configurations where wire bundles of mixed gauges and currents are employed with varying external insulation jacket surface properties. Thermal modeling has been employed in an attempt to develop techniques to assist in ampacity determination for these complex configurations. Previous developments allowed analysis of wire bundle configurations but was constrained to configurations comprised of less than 50 elements. Additionally, for vacuum analyses, configurations with very low emittance external jackets suffered from numerical instability in the solution. A new thermal modeler is presented allowing for larger configurations and is not constrained for low bundle infrared emissivity calculations. Formulation of key internal radiation and interface conductance parameters is discussed including the effects of temperature and air pressure on wire to wire thermal conductance. Test cases comparing model-predicted ampacity and that calculated from standards documents are presented.
Thermal Analysis of the Fair SIS300 Model Dipole
Sorbi, M.; Alessandria, F.; Bellomo, G.; Fabbricatore, P.; Farinon, S.; Gambardella, U.; Musenich, R.; Volpini, G.
2010-04-01
Design activities, conductor R&D and model coil construction are under way for the development of a curved superconducting dipole for the fast cycled SIS300 synchrotron at FAIR at GSI. The main target is the construction within 2009 of a half-length model magnet (cold mass fully integrated in a horizontal cryostat). This magnet is designed for a maximum central field of 4.5 T in a bore of 100 mm, with a ramp rate of 1 T/s. The magnetic length of the model is 3.9 m with a curvature radius of 66.67 m (27 mm of sagitta). This paper describes the thermal analysis of the magnet, based on the estimated values of the losses in the cold mass. The study has been performed with 2-D finite element codes, both in steady state and transient analysis. The study has been completed with measurements of overall thermal exchange coefficient between the kapton-insulated cables and the supercritical helium, in order to validate the adopted assumptions about the material thermal properties.
Engine System Model Development for Nuclear Thermal Propulsion
Nelson, Karl W.; Simpson, Steven P.
2006-01-01
In order to design, analyze, and evaluate conceptual Nuclear Thermal Propulsion (NTP) engine systems, an improved NTP design and analysis tool has been developed. The NTP tool utilizes the Rocket Engine Transient Simulation (ROCETS) system tool and many of the routines from the Enabler reactor model found in Nuclear Engine System Simulation (NESS). Improved non-nuclear component models and an external shield model were added to the tool. With the addition of a nearly complete system reliability model, the tool will provide performance, sizing, and reliability data for NERVA-Derived NTP engine systems. A new detailed reactor model is also being developed and will replace Enabler. The new model will allow more flexibility in reactor geometry and include detailed thermal hydraulics and neutronics models. A description of the reactor, component, and reliability models is provided. Another key feature of the modeling process is the use of comprehensive spreadsheets for each engine case. The spreadsheets include individual worksheets for each subsystem with data, plots, and scaled figures, making the output very useful to each engineering discipline. Sample performance and sizing results with the Enabler reactor model are provided including sensitivities. Before selecting an engine design, all figures of merit must be considered including the overall impacts on the vehicle and mission. Evaluations based on key figures of merit of these results and results with the new reactor model will be performed. The impacts of clustering and external shielding will also be addressed. Over time, the reactor model will be upgraded to design and analyze other NTP concepts with CERMET and carbide fuel cores.
Modeling thermal sensation in a Mediterranean climate—a comparison of linear and ordinal models
Pantavou, Katerina; Lykoudis, Spyridon
2014-08-01
A simple thermo-physiological model of outdoor thermal sensation adjusted with psychological factors is developed aiming to predict thermal sensation in Mediterranean climates. Microclimatic measurements simultaneously with interviews on personal and psychological conditions were carried out in a square, a street canyon and a coastal location of the greater urban area of Athens, Greece. Multiple linear and ordinal regression were applied in order to estimate thermal sensation making allowance for all the recorded parameters or specific, empirically selected, subsets producing so-called extensive and empirical models, respectively. Meteorological, thermo-physiological and overall models - considering psychological factors as well - were developed. Predictions were improved when personal and psychological factors were taken into account as compared to meteorological models. The model based on ordinal regression reproduced extreme values of thermal sensation vote more adequately than the linear regression one, while the empirical model produced satisfactory results in relation to the extensive model. The effects of adaptation and expectation on thermal sensation vote were introduced in the models by means of the exposure time, season and preference related to air temperature and irradiation. The assessment of thermal sensation could be a useful criterion in decision making regarding public health, outdoor spaces planning and tourism.
Wei, Katy; Moinat, Maxim; Maarleveld, Timo R; Bruggeman, Frank J
2014-07-29
Signal transduction by prokaryotes almost exclusively relies on two-component systems for sensing and responding to (extracellular) signals. Here, we use stochastic models of two-component systems to better understand the impact of stochasticity on the fidelity and robustness of signal transmission, the outcome of autoregulatory gene expression and the influence of cell growth and division. We report that two-component systems are remarkably robust against copy number fluctuations of the signalling proteins they are composed of, which enhances signal transmission fidelity. Furthermore, we find that due to stochasticity these systems can get locked in an active state for extended time periods when (initially high) signal levels drop to zero. This behaviour can contribute to a bet-hedging adaptation strategy, aiding survival in fluctuating environments. Additionally, autoregulatory gene expression can cause two-component systems to become bistable at realistic parameter values. As a result, two sub-populations of cells can co-exist-active and inactive cells, which contributes to fitness in unpredictable environments. Bistability proved robust with respect to cell growth and division, and is tunable by the growth rate. In conclusion, our results indicate how single cells can cope with the inevitable stochasticity occurring in the activity of their two-component systems. They are robust to disadvantageous fluctuations that scramble signal transduction and they exploit beneficial stochasticity that generates fitness-enhancing heterogeneity across an isogenic population of cells.
A Temperature-Dependent Thermal Model of IGBT Modules Suitable for Circuit-Level Simulations
Wu,Rui; Wang, Huai; Ma, Ke; Ghimire, Pramod; Iannuzzo, Francesco; Blaabjerg, Frede
2014-01-01
Thermal impedance of IGBT modules may vary with operating conditions due to that the thermal conductivity and heat capacity of materials are temperature dependent. This paper proposes a Cauer thermal model for a 1700 V/1000 A IGBT module with temperature-dependent thermal resistances and thermal capacitances. The temperature effect is investigated by Finite Element Method (FEM) simulation based on the geometry and material information of the IGBT module. The developed model is ready for circu...
Uranus evolution models with simple thermal boundary layers
Nettelmann, N.; Wang, K.; Fortney, J. J.; Hamel, S.; Yellamilli, S.; Bethkenhagen, M.; Redmer, R.
2016-09-01
The strikingly low luminosity of Uranus (Teff ≃ Teq) constitutes a long-standing challenge to our understanding of Ice Giant planets. Here we present the first Uranus structure and evolution models that are constructed to agree with both the observed low luminosity and the gravity field data. Our models make use of modern ab initio equations of state at high pressures for the icy components water, methane, and ammonia. Proceeding step by step, we confirm that adiabatic models yield cooling times that are too long, even when uncertainties in the ice:rock ratio (I:R) are taken into account. We then argue that the transition between the ice/rock-rich interior and the H/He-rich outer envelope should be stably stratified. Therefore, we introduce a simple thermal boundary and adjust it to reproduce the low luminosity. Due to this thermal boundary, the deep interior of the Uranus models are up to 2-3 warmer than adiabatic models, necessitating the presence of rocks in the deep interior with a possible I:R of 1 × solar. Finally, we allow for an equilibrium evolution (Teff ≃ Teq) that begun prior to the present day, which would therefore no longer require the current era to be a "special time" in Uranus' evolution. In this scenario, the thermal boundary leads to more rapid cooling of the outer envelope. When Teff ≃ Teq is reached, a shallow, subadiabatic zone in the atmosphere begins to develop. Its depth is adjusted to meet the luminosity constraint. This work provides a simple foundation for future Ice Giant structure and evolution models, that can be improved by properly treating the heat and particle fluxes in the diffusive zones.
Muzamal, Uzma; Gomez, Daniel; Kapadia, Fenika; Golemi-Kotra, Dasantila
2014-01-01
The response to cationic antimicrobial peptides (CAMPs) in Staphylococcus aureus relies on a two-component system (TCS), GraSR, an auxiliary protein GraX and an ATP-binding cassette (ABC) transporter, VraF/G. To understand the signal transduction mechanism by GraSR, we investigated the kinase activity of the cytoplasmic domain of histidine kinase GraS and the interaction with its cognate response regulator GraR. We also investigated interactions among the auxiliary protein GraX, GraS/R and the ATPase protein of the ABC transporter, VraF. We found that GraS lacks autophosphorylation activity, unlike a similar histidine kinase, BceS, of Bacillus subtilis. In addition, the interaction between GraS and GraR is very weak in comparison to the stronger interaction observed between BceS and its conjugated response regulator, BceR, suggesting that CAMP signaling may not flow directly from GraS to GraR. We found that the auxiliary protein GraX interacts with VraF and GraR, and requires the histidine phosphotransfer and dimerization domain of GraS to interact with this protein. Further, VraF requires the GraS region that connects the membrane-bound domain with the cytoplasmic domain of this protein for interaction with GraS. The interactions of GraX with GraS/R and VraF indicate that GraX may serve as a scaffold to bring these proteins in close proximity to GraS, plausibly to facilitate activation of GraS to ultimately transduce the signal to GraR.
Elimination of Nonlinear Deviations in Thermal Lattice BGK Models
Chen, Y; Hongo, T; Chen, Yu; Ohashi, Hirotada; Akiyam, Mamoru
1993-01-01
Abstracet: We present a new thermal lattice BGK model in D-dimensional space for the numerical calculation of fluid dynamics. This model uses a higher order expansion of equilibrium distribution in Maxwellian type. In the mean time the lattice symmetry is upgraded to ensure the isotropy of 6th order tensor. These manipulations lead to macroscopic equations free from nonlinear deviations. We demonstrate the improvements by conducting classical Chapman-Enskog analysis and by numerical simulation of shear wave flow. The transport coefficients are measured numerically, too.
Forced thermal cycling of catalytic reactions: experiments and modelling
DEFF Research Database (Denmark)
Jensen, Søren; Olsen, Jakob Lind; Thorsteinsson, Sune;
2007-01-01
Recent studies of catalytic reactions subjected to fast forced temperature oscillations have revealed a rate enhancement increasing with temperature oscillation frequency. We present detailed studies of the rate enhancement up to frequencies of 2.5 Hz. A maximum in the rate enhancement is observed...... at about 1 Hz. A model for the rate enhancement that includes the surface kinetics and the dynamic partial pressure variations in the reactor is introduced. The model predicts a levelling off of the rate enhancement with frequency at about 1 Hz. The experimentally observed decrease above 1 Hz is explained...... by dynamic thermal limitations of the reactor. (c) 2007 Elsevier B.V. All rights reserved....
Thermal Storage Power Balancing with Model Predictive Control
DEFF Research Database (Denmark)
Halvgaard, Rasmus; Poulsen, Niels Kjølstad; Madsen, Henrik
2013-01-01
The method described in this paper balances power production and consumption with a large number of thermal loads. Linear controllers are used for the loads to track a temperature set point, while Model Predictive Control (MPC) and model estimation of the load behavior are used for coordination....... The total power consumption of all loads is controlled indirectly through a real-time price. The MPC incorporates forecasts of the power production and disturbances that influence the loads, e.g. time-varying weather forecasts, in order to react ahead of time. A simulation scenario demonstrates...
Dou, Mei; Zhang, Qiong; Meng, Yang; Li, Jing; Lu, Yiming; Zhu, Kaiguang
2017-01-01
Conductivity-depth imaging (CDI) of data is generally applied in identifying conductive targets. CDI results will be affected by the bird attitude especially the pitch of the receiver coil due to the attitude, velocity of the aircraft and the wind speed. A CDI algorithm with consideration of pitch is developed based on two-component measurement. A table is established based on two-component B field response and the pitch is considered as a parameter in the table. Primary advantages of this method are immunity to pith errors and better resolution of conductive layers than results without consideration of pith. Not only the conductivity but also the pitch can be obtained from this algorithm. Tests on synthetic data demonstrate that the CDI results with pitch based on two-component measurement does a better job than the results without consideration of pitch and the pitch obtained is close to the true model in many circumstances.
Developing a Cost Model and Methodology to Estimate Capital Costs for Thermal Energy Storage
Energy Technology Data Exchange (ETDEWEB)
Glatzmaier, G.
2011-12-01
This report provides an update on the previous cost model for thermal energy storage (TES) systems. The update allows NREL to estimate the costs of such systems that are compatible with the higher operating temperatures associated with advanced power cycles. The goal of the Department of Energy (DOE) Solar Energy Technology Program is to develop solar technologies that can make a significant contribution to the United States domestic energy supply. The recent DOE SunShot Initiative sets a very aggressive cost goal to reach a Levelized Cost of Energy (LCOE) of 6 cents/kWh by 2020 with no incentives or credits for all solar-to-electricity technologies.1 As this goal is reached, the share of utility power generation that is provided by renewable energy sources is expected to increase dramatically. Because Concentrating Solar Power (CSP) is currently the only renewable technology that is capable of integrating cost-effective energy storage, it is positioned to play a key role in providing renewable, dispatchable power to utilities as the share of power generation from renewable sources increases. Because of this role, future CSP plants will likely have as much as 15 hours of Thermal Energy Storage (TES) included in their design and operation. As such, the cost and performance of the TES system is critical to meeting the SunShot goal for solar technologies. The cost of electricity from a CSP plant depends strongly on its overall efficiency, which is a product of two components - the collection and conversion efficiencies. The collection efficiency determines the portion of incident solar energy that is captured as high-temperature thermal energy. The conversion efficiency determines the portion of thermal energy that is converted to electricity. The operating temperature at which the overall efficiency reaches its maximum depends on many factors, including material properties of the CSP plant components. Increasing the operating temperature of the power generation
Directory of Open Access Journals (Sweden)
Andrea Procaccini
Full Text Available Predictive understanding of the myriads of signal transduction pathways in a cell is an outstanding challenge of systems biology. Such pathways are primarily mediated by specific but transient protein-protein interactions, which are difficult to study experimentally. In this study, we dissect the specificity of protein-protein interactions governing two-component signaling (TCS systems ubiquitously used in bacteria. Exploiting the large number of sequenced bacterial genomes and an operon structure which packages many pairs of interacting TCS proteins together, we developed a computational approach to extract a molecular interaction code capturing the preferences of a small but critical number of directly interacting residue pairs. This code is found to reflect physical interaction mechanisms, with the strongest signal coming from charged amino acids. It is used to predict the specificity of TCS interaction: Our results compare favorably to most available experimental results, including the prediction of 7 (out of 8 known interaction partners of orphan signaling proteins in Caulobacter crescentus. Surveying among the available bacterial genomes, our results suggest 15∼25% of the TCS proteins could participate in out-of-operon "crosstalks". Additionally, we predict clusters of crosstalking candidates, expanding from the anecdotally known examples in model organisms. The tools and results presented here can be used to guide experimental studies towards a system-level understanding of two-component signaling.