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Numerical solutions for the periodic laminar boundary layer mixed convection flow around the surface of a heated sphere in the presence of viscous dissipation have been obtained by solving the governing equations using an implicit finite difference numerical technique. The fluid under consideration is assumed to be viscous and incompressible. Periodic momentum and thermal boundary layer profiles for different positions of x around the surface of the sphere are evaluated. The features of the obtained results for different values of mixed convection parameter [lambda], Prandtl number Pr, viscous dissipation parameter N, and frequency parameter [omega] are shown graphically. The obtained results confirm significant effect of all these mentioned parameters on periodic momentum and thermal boundary layer mixed convection flow around different positions of the sphere. Key words: periodic momentum and thermal boundary layer thicknesses, mixed convection, viscous dissipation, finite difference method, sphere. Nous utilisons une technique implicite aux differences finies pour solutionner les equations directrices et obtenir les solutions numeriques pour l'ecoulement convectif mixe de la couche limite laminaire periodique autour de la surface d'une sphere chauffee en presence de dissipation visqueuse. Nous posons que le fluide considere est visqueux et incompressible. Nous evaluons l'impulsion periodique et les profiles de la couche limite pour differentes valeurs de x autour de la surface de la sphere. Nous presentons graphiquement les caracteristiques des resultats obtenus pour differentes valeurs du parametre de convexion mixe [lambda], du nombre de Prandtl Pr, du parametre de dissipation visqueuse N et de la frequence [omega]. [Traduit par la Redaction] Mots-cles: impulsion periodique et epaisseur de la couche limite thermique, convexion mixe, dissipation visqueuse, methode aux differences finies, sphere., 1. Introduction Oscillatory flow problems with steady and unsteady oncoming stream find applications in many interesting and important fluid mechanical systems: heat exchangers, thermal and nuclear power plants, etc. Study [...]

The area of the event horizon of a black hole ([A.sub.eh]) is so far linked only with its entropy (SBH). In this theoretical investigation, it is shown that relating [A.sub.eh] only to SBH is inadequate, because [A.sub.eh] is linked to the black hole's negentropy, which encompasses its entropy. Increasing [A.sub.eh] of black holes that grow now follows from the negentropy theorem (NET) and also from the well-known area theorem. The decreasing [A.sub.eh] of black holes that decay follows from the converse to NET and is not a violation of the area theorem. The corollary to NET is proved for the case when two dissipative structures merge, which is the basis for the coalescence of black holes. The converse of corollary to NET explains negentropy loss due to splitting of a dissipative structure. When applied to black hole explosion (i.e., splitting into an infinite number of parts), converse of corollary to NET reduces to converse of NET. The entropy/energy ratio of the exported Hawking radiance from black holes contributes to the entropy increase of the universe. These aspects justify the consideration of black holes as thermodynamic dissipative structures. Key words: black hole, dissipative structure, event horizon, Hawking radiance, negentropy. La surface de l'horizon d'un trou noir ([A.sub.eh]) a ete jusqu'a maintenant associee seulement a son entropie (SBH). Dans la presente etude theorique, nous montrons que relier [A.sub.eh] uniquement fi SBH est inadequat, parce que [A.sub.eh] est en fait reliee a la neguentropie du trou noir, qui comprend l'entropie. L'augmentation de [A.sub.eh] des trous noirs qui grossissent suit maintenant le theoreme de neguentropie (NET) ainsi que le theoreme sur la surface de Hawking. La diminution de la surface des trous noirs qui se desintegrent suit l'opposee du NET et n'est pas une violation du theoreme sur la surface. Le corollaire du NET est demontre pour le cas oU deux structures dissipatives fusionnent, ce qui est la base de la fusion des trous noirs. L'oppose du corollaire du NET explique la perte de neguentropie due a la separation de structures dissipatives. Lorsque appliquee a l'explosion d'un trou noir (i.e., son explosion en un nombre infini de morceaux) l'oppose du corollaire du NET se reduit fi l'oppose du NET. Le rapport entropie/ energie de la radiation de Hawking emise par le trou noir contribue a l'augmentation de l'entropie de l'univers. Ces resultats justifient de considerer les trous noirs comme des structures thermodynamiques dissipatives. [Traduit par la Redaction] Mots-cles : trou noir, structure dissipative, horizon du trou noir, radiation de Hawking, neguentropie., 1. Introduction Non-equilibrium thermodynamics led to the understanding that the spontaneous creation, existence, and growth of an unstable dissipative structure (DS) (a black hole will be shown to be one [...]

In this paper, we consider a charged black hole in three dimensions with a scalar charge and discuss energy loss of a heavy particle moving near the black hole horizon. This analysis is useful when anti-de Sitter space--conformal field theory correspondence is applied. We find that an electric charge of a black hole increases the drag force but a scalar charge decreases it. PACS Nos.: 04.70.Bw, 11.25.-w, 11.25.Tq. Nous etudions ici un trou noir electriquement charge en trois dimensions avec une charge scalaire et analysons la perte en energie d'une particule massive se deplacant pres de l'horizon du trou noir. Ceci peut etre utile dans un contexte d'etude AdS-CFT. Nous trouvons que la charge electrique du trou noir augmente la force de trainee, mais que la charge scalaire la diminue. [Traduit par la Redaction], 1. Introduction Because they are easier to study, lower-dimensional theories may be used as toy models to investigate some fundamental ideas that may lead to better understanding of higher-dimensional theories [...]

This investigation deals with the rotation of magneto-thermoelastic solid with voids subjected to thermal loading due to laser pulse. The bounding plane surface is heated by a non-Gaussian laser beam. The entire porous medium is rotated with a uniform angular velocity. The problem is studied in the context of Green-Naghdi (GN) theory of types II and III, with the effect of rotation, magnetic field, thermal loading and voids. Normal mode analysis is used to solve the physical problem to obtain the exact expressions for the displacement components, stresses, temperature distribution, and change in the volume fraction field, which have been shown graphically by comparison between two types of GN theory (types II and III) in the presence and the absence of rotation and magnetic field and for two values of time on thermoelastic material with voids. PACS Nos.: 62.20.Dc, 81.40.Jj. Nous etudions la rotation de solides magneto-thermo-elastiques avec des cavites, soumis a une charge thermique venant d'une impulsion laser. La surface frontiere est chauffee par un faisceau laser non gaussien. La totalite du milieu poreux tourne avec une vitesse angulaire uniforme. Notre etude se fait dans le cadre des theories de Green-Naghdi (GN) de types II et III, incluant les effets de rotation, de champ magnetique, de charge thermique et de porosite. Nous utilisons une analyse en modes normaux pour solutionner le probleme physique et obtenir les expressions exactes pour les composantes de deplacement, les efforts, la distribution en temperature et les changements du champ de volume fractionnaire, qui sont presentes graphiquement en comparant les deux theories II et III de GN, avec et sans rotation et champ magnetique pour deux valeurs de temps de propagation. [Traduit par la Redaction], 1. Introduction In the classical theory of thermoelasticity, Fourier's heat conduction theory assumes that the thermal disturbances propagate at infinite speed, which is unrealistic from the physical point of view. [...]

The long-predicted suppression of quasiparticle dissipation in a Josephson junction when the phase difference across the junction is [pi] is inferred from a sharp maximum in the energy relaxation time of a superconducting artificial atom. Quasiparticle dissipation in a Josephson junction Josephson junctions, which consist of two superconductors connected by a weak link, have a central role in quantum electronic applications, such as in sensitive magnetic field detectors, high-speed processing and quantum information networks. However, a fundamental prediction concerning the Josephson effect has not yet been confirmed. It is known that the current flowing through a Josephson junction is made up from superconducting Cooper pairs as well as excitations called quasiparticles, which contribute in a few different ways. One contribution causes dissipation but can in theory be suppressed by tuning the phase difference between the superconductors. This has been achieved experimentally. Ioan Pop et al. have made a qubit comprising a Josephson junction. The energy relaxation time of this qubit increases by almost two orders of magnitude owing to the suppression of quasiparticle dissipation. This finding confirms the existence of a fundamental quantum phenomenon predicted over 50 years ago. Owing to the low-loss propagation of electromagnetic signals in superconductors, Josephson junctions constitute ideal building blocks for quantum memories, amplifiers, detectors and high-speed processing units, operating over a wide band of microwave frequencies. Nevertheless, although transport in superconducting wires is perfectly lossless for direct current, transport of radio-frequency signals can be dissipative in the presence of quasiparticle excitations above the superconducting gap.sup.1. Moreover, the exact mechanism of this dissipation in Josephson junctions has never been fully resolved experimentally. In particular, Josephson's key theoretical prediction that quasiparticle dissipation should vanish in transport through a junction when the phase difference across the junction is [pi] (ref. 2) has never been observed.sup.3. This subtle effect can be understood as resulting from the destructive interference of two separate dissipative channels involving electron-like and hole-like quasiparticles. Here we report the experimental observation of this quantum coherent suppression of quasiparticle dissipation across a Josephson junction. As the average phase bias across the junction is swept through [pi], we measure an increase of more than one order of magnitude in the energy relaxation time of a superconducting artificial atom. This striking suppression of dissipation, despite the presence of lossy quasiparticle excitations above the superconducting gap, provides a powerful tool for minimizing decoherence in quantum electronic systems and could be directly exploited in quantum information experiments with superconducting quantum bits., Author(s): Ioan M. Pop [sup.1] , Kurtis Geerlings [sup.1] , Gianluigi Catelani [sup.1] [sup.2] , Robert J. Schoelkopf [sup.1] , Leonid I. Glazman [sup.1] , Michel H. Devoret [sup.1] Author [...]

Engineered dissipation is used to deterministically produce and stabilize entanglement between two trapped-ion quantum bits, independently of their initial states; the entanglement is stabilized even in the presence of experimental noise and decoherence. Harnessing dissipation in entangled quantum states Entangled states are a key resource in fundamental quantum physics, quantum cryptography and quantum computation. It has been generally assumed that the creation of such states requires the avoidance of contact with a dissipative environment, and minimization of decoherence. Some studies have shown, however, that dissipative interactions can be used to preserve coherence, and in this issue of Nature two groups demonstrate this principle for continuously driven physical systems. Lin et al. use engineered dissipation to deterministically produce and stabilize entanglement between two trapped-ion qubits, independent of their initial state. Shankar et al. use an autonomous feedback scheme to counteract decoherence and demonstrate the stabilization of an entangled Bell state of a quantum register of two superconducting qubits for an arbitrary time. This approach may be applied to a broad range of experimental systems to achieve desired quantum dynamics or steady states. Entangled states are a key resource in fundamental quantum physics, quantum cryptography and quantum computation.sup.1. Introduction of controlled unitary processes--quantum gates--to a quantum system has so far been the most widely used method to create entanglement deterministically.sup.2. These processes require high-fidelity state preparation and minimization of the decoherence that inevitably arises from coupling between the system and the environment, and imperfect control of the system parameters. Here we combine unitary processes with engineered dissipation to deterministically produce and stabilize an approximate Bell state of two trapped-ion quantum bits (qubits), independent of their initial states. Compared with previous studies that involved dissipative entanglement of atomic ensembles.sup.3 or the application of sequences of multiple time-dependent gates to trapped ions.sup.4, we implement our combined process using trapped-ion qubits in a continuous time-independent fashion (analogous to optical pumping of atomic states). By continuously driving the system towards the steady state, entanglement is stabilized even in the presence of experimental noise and decoherence. Our demonstration of an entangled steady state of two qubits represents a step towards dissipative state engineering, dissipative quantum computation and dissipative phase transitions.sup.5,6,7. Following this approach, engineered coupling to the environment may be applied to a broad range of experimental systems to achieve desired quantum dynamics or steady states. Indeed, concurrently with this work, an entangled steady state of two superconducting qubits was demonstrated using dissipation.sup.8., Author(s): Y. Lin [sup.1] , J. P. Gaebler [sup.1] , F. Reiter [sup.2] , T. R. Tan [sup.1] , R. Bowler [sup.1] , A. S. Sørensen [sup.2] , D. Leibfried [...]

A dataset of undrained cyclic triaxial tests for liquefaction with parametrically changing relative density and fines content is reviewed and interpreted in the scope of energy. It is found that the strain amplitude or pore- pressure buildup during cyclic loading is uniquely correlated not only to the energy dissipated in soil specimens, but also to strain energy given from outside. Hence, an energy-based method (EBM) is developed in which liquefaction potential can be evaluated by comparing strain energy for liquefaction in a sand layer with upcoming seismic energy without regard to the differences in seismic motions. Comparative studies in soil models demonstrate that the effect of various input motions is intrinsically included in EBM, whereas it has to be considered by choosing proper coefficients in a conventional stress-based method (SBM). Another significant difference is that liquefaction potential tends to be higher for a shallower depth in EBM, while it is vice versa in SBM in a uniform sand deposit. Key words: liquefaction potential, dissipated energy, upward wave energy, earthquake magnitude, cyclic triaxial test. Une serie de donnees d'essais triaxiaux cycliques non draines, servant a evaluer la liquefaction et dont la densite relative et le contenu en particules fines ont ete varies de facon parametrique, ont ete revises et interpretes en fonction de l'energie. Il a ete determine que l'amplitude de la deformation, ou l'accumulation des pressions interstitielles, durant les sollicitations cycliques est correlee non seulement a l'energie dissipee dans les echantillons de sol mais aussi a l'energie de deformation recue de l'exterieur. Ainsi, une methode basee sur l'energie (MBE) est developpee. Cette methode permet d'evaluer le potentiel de liquefaction en comparant l'energie de deformation de la liquefaction dans une couche de sable a l'energie sismique qui arrive, sans considerer les differences de mouvements sismiques. Des etudes comparatives dans des sols modeles demontrent que l'effet de differents mouvements initiaux est inclus intrinsequement dans le MBE, tandis qu'il doit etre considere par le choix d'un coefficient adequat dans une methode conventionnelle basee sur les contraintes (MBC). Une autre difference importante est que le potentiel de liquefaction tend a etre plus eleve pour des profondeurs plus faibles avec la MBE, tandis que l'inverse est valide pour la MBC dans un depot de sable uniforme. [Traduit par la Redaction] Mots-cles: potentiel de liquefaction, energie dissipee, energie d'onde vers le haut, magnitude d'un seisme, essai triaxial cyclique., Introduction From the dawn of liquefaction research, a stress-based method (SBM), comparing undrained cyclic strength with seismically induced shear stress, was employed (Seed and Idriss 1971) and standardized in engineering [...]

In this paper, we investigate the dissipative dynamics of a driven two-level quantum dot weakly coupled with a structured reservoir that is characterized by a double-peaked spectral function. We discuss the time-dependent dissipation coefficients and the Bloch vector by using a time-local non-markovian master equation. It is shown that the decay rates display temporarily negative values that can be manipulated by the distance between the two peaks in the spectral function. For the strong pumping case, the nonsecular effect gives rise to the non-markovian dynamics of the Bloch vector. However, for the weak pumping case, the non-markovian dynamics show up when contributions from secular and nonsecular terms are comparable. In the long time limit, the signature of non-markovian dynamics disappears and the behavior obeys Fermi's golden rule. PACS Nos: 03.65.Yz, 03.65.Ta Nous analysons ici la dynamique dissipative d'une boite quantique a deux niveaux faiblement couplee a un reservoir structure qui est caracterise par une fonction spectrale a deux pics. Nous les coefficients de dissipation dependant du temps et le vecteur de Bloch, en utilisant une equation maitresse non Markovienne a temps local. Nous montrons que les taux de desintegration montrent des valeurs temporairement negatives qui peuvent etre ajustees par la distance entre les deux pics de la fonction spectrale. Dans le cas d'un pompage fort, l'effet non seculaire donne naissance a la dynamique non Markovienne du vecteur de Bloch. Cependant, dans le cas de pompage faible, la dynamique non Markovienne apparait lorsque les contributions provenant des termes seculaires et non seculaires sont comparables. Dans la limite des temps tres longs, la signature de la dynamique non Markovienne disparait et le comportement obeit a la regle d'or de Fermi. [Traduit par la Redaction], 1. Introduction Dissipation plays an important role in the interaction between the system and the environment. Generally speaking, dissipation cannot be avoided and it is involved in the system dynamics [...]

In this paper, we propose a photonic Josephson junction in two coupled, Kerr-type, nonlinear cavities. In the coherent state representation, saddle point analysis of the system action yields a mean-field description of the coherent photon current. The photonic analogs of the Rabi oscillation, the AC effect as well as the Shapiro resonance are found. The tunneling dynamics dramatically change at a critical point that is determined by the relative value of on-site nonlinear strength versus intercavity tunneling rate. We discuss this critical behavior for various parameters in detail. Furthermore, the influences of the initial conditions and the environment-induced pumping-dissipation process on the system dynamics are also studied. PACS Nos: 42.50.Pq, 03.75.Lm, 42.65.Sf Nous proposons ici une jonction de Josephson photonique dans deux cavites non lineaires de type Kerr. Dans la representation de l'etat coherent, l'analyse du point de selle de l'action du systeme donne une description en champ moyen du courant de photon coherent. Nous trouvons l'analogue photonique de l'oscillation de Rabi et l'effet CA, aussi bien que la resonance de Shapiro. Nous determinons le changement dramatique dans la dynamique de l'effet tunnel par la valeur relative de la force de la non linearite versus le taux de transfert inter-cavite par effet tunnel. Nous analysons minutieusement ce comportement critique pour differentes valeurs de parametre. Nous etudions egalement l' influence sur le systeme des conditions initiales et du mecanisme de pompage-dissipation induit par l'environnement. [Traduit par la Redaction], 1. Introduction The Josephson effect is a macroscopic tunneling phenomenon. It stems from the inherent coherence of the constituent quantum systems. The resulting Josephson oscillations have been discussed in systems [...]

With international trends of energy saving and low emissions, pursuing healthy and low-emission buildings as well as ensuring the quality of interior environments have become critical issues in the 21st century. Bymeans of applying critical flicker frequency to the quantitative assessment of objective visual fatigue, and using a visual fatigue questionnaire to evaluate subjective visual fatigue, this study attempts, in 500lux and 200lux lighting environments, to investigate the influence of visual fatigue on working performance when using visual display terminals. Changes in productivity as a result of subjective and objective visual fatigue under different artificial lights have been analysed. The outcome shows that with light-emitting diode lighting, the sense of alertness and productivity was better. In terms of productivity, the 200lux lighting environment was even better than the 500lux lighting standard for a general operation environment, as suggested by the Illumination Engineering Society. Keywords: Critical flicker frequency; light-emitting diode; productivity; visual display terminal; visual fatigue, NOTATIONS L(t) indicates actual brightness of a periodically changing light, which is a periodical function of time. T indicates period. What human eyes feel is the average brightness of a [...]

The analysis of plunging flows using energy dissipation hypothesis is presented in this paper. The classic two-control- volume theory has recently been found questionable and needs to be corrected. In this study, we avoid the questionable part of that framework and use a single control volume for the analysis of plunging flows. Furthermore, we hypothesize that the increase in kinetic energy in the underflow and entrained flow should be no greater than the loss in potential energy as the inflow plunges. In the current framework, the entrained flow rate does not exceed approximately 40% of the total inflow rate. The densimetric Froude number at the plunge point, [F.sub.dp] = q/ [square root of g'[H.sup.3.sub.p]], where q=inflow rate per unit width; g' = reduced gravity of inflow; and [H.sub.p] = flow depth at the plunge point, is typically in the range of 0.3 < [F.sub.dp] < 0.6 for plunging flows in a constant width channel. DOI: 10.1061/(ASCE)HY.1943-7900.0000176 CE Database subject headings: Energy dissipation; Density flow; Lakes; Plunging flow; Reservoirs. Author keywords: Energy dissipation; Density flow; Lakes; Plunging flow; Reservoirs.

An analysis is performed to study the effect of variable viscosity and variable thermal conductivity on the flow and heat transfer of a thin viscoelastic liquid (obeying Walters' liquid B model) film on a horizontal unsteady stretching sheet taking into account the effect of viscous dissipation. The fluid viscosity is assumed to decrease exponentially with temperature but the thermal conductivity is assumed to vary as a linear function of temperature. Numerical solutions are obtained for some representative values of the viscosity and thermal conductivity variation parameters, unsteadiness parameter, and Eckert number. Typical temperature and velocity profiles, dimensionless film thickness, free-surface velocity and temperature, local skin-friction coefficient, and the local surface heat flux are obtained for a wide range of governing parameters. In general, it is found that a viscoelastic fluid is more sensitive to the variable fluid properties effect than a Newtonian fluid. Also, for constant and (or) variable fluid properties, the film thickness and the local surface heat flux of a viscoelastic fluid is small compared to that of a Newtonian fluid. For all values of the variable viscosity parameter and for both viscoelastic and Newtonian fluid films, the viscous dissipation effect increases the free-surface temperature significantly whereas it reduces the heat transfer rate markedly. However, viscous dissipation does not influence the velocity profiles of both Newtonian and viscoelastic liquid films impressively although the film thickness changes noticeably. PACS No: 47.15.gm Nous etudions l'effet d'une viscosite variable et d'une conductivite thermique variable sur l'ecoulement et le transfert de chaleur d'une couche mince de liquide viscoelastique (qui obeit au modele liquide B de Walters) sur une surface horizontale instable extensible, tenant compte d'une dissipation visqueuse. La viscosite du fluide est presumee decroitre exponentiellement avec la temperature, mais la conductivite thermique est supposee etre une fonction lineaire de la temperature. Nous obtenons des solutions numeriques pour des valeurs representatives des parametres de variation de la viscosite et de la conductivite; thermique, du parametre d'instabilite et du nombre d'Eckert. Nous obtenons des profils types de temperature et de vitesse, ainsi que l'eepaisseur adimensionnee de la couche, la temperature et la vitesse en surface libre, le coefficient de friction de peau local et le flux thermique local de surface. En general, nous observons qu'un fluide viscoelastique est plus sensible aux effets des proprietes variables du fluide qu'un fluide Newtonien. Egalement, pour des proprietes constantes/variables du fluide, l'eepaisseur de la couche et le flux thermique local du viscoelastique sont faibles compares au fluide Newtonien. Pour toutes les valeurs du parametre de viscosite variable et pour les deux types de couche de fluide, viscoelastique et Newtonien, l'effet de dissipation visqueuse augmente de facon significative la temperature de la surface libre, alors qu'il reduit de facon marquee le taux de transfert de chaleur. Cependant, la dissipation visqueuse n'influence pas beaucoup les profiles de vitesse des couches de fluide viscoelastique et Newtonien, mais l'epaisseur de la couche change de facon notable. [Traduit par la Redaction], 1. Introduction In recent years the analyses of the flow of a thin liquid film have attracted the attention of a number of researchers because of the possible applications in [...]

Plants protect themselves against the deleterious effects of high light intensities by inducing a mechanism ubiquitous among plants known as energy dissipation, which safely converts excess light to heat before it can lead to the formation of free radicals. Mutants possessing a deletion of the psbS gene, such as the npq4 mutant, cannot perform energy dissipation and thus offer an opportunity to assess the importance of this process to plant function. In a temperate light environment, greenhouse- grown npq4 mutants of Arabidopsis thaliana had smaller rosette diameters and leaf numbers. The reduction in size observed in npq4 plants was associated with fewer floral stalks, fewer fruits, lower whole-plant and individual seed masses, and lower germination rates. In the field, npq4 mutants developed fewer fruits. Ariel a controlled exposure to high light stress, both PSII efficiency and C[O.sub.2] assimilation were more significantly compromised in npq4 mutants at low light intensities, but not at high light intensities. Thus, the protective nature of energy dissipation manifests in light environments that include periods of high light, which predispose plants to PSII photoinactivation, and periods of low light, when PSI1 photoinactivation decreases the rate of photosynthesis. Key words: Arabidopsis thaliana; Brassicaceae; energy dissipation; nonphotochemical quenching; npq4 mutant; photosynthesis; photosystem II: psbS; zeaxanthin. doi: 10.3732/ajb.0900163

This paper deals with the roller length and energy loss of a large variety of hydraulic jumps in horizontal and sloping channels. The supercritical upstream flow originated from a standard ogee weir. A stilling basin with bottom slopes of 0.0, -0.025, -0.050, -0.075, and -0.100 was used to generate the jumps. Based on the energy principle, a semiempirical method to predict the roller length is presented. Predictions based on the proposed method agree well with the results reported by the authors and other researchers. It is shown that the energy loss in the classical jump is greater than that in any jump forming on negative or positive slopes. Key words: hydraulic jump, sloping channel, adverse slope, roller length, energy loss. Cei article traite de la longueur des rouleaux et de la perte d'energie d'une grande variete de ressauts hydrauliques dans les canaux horizontaux et en pente. L'ecoulement surcritique en amont provenait d'un deversoir en doucine standard. Un bassin de tranquillisation muni de pentes de fond de 0.0, -0,025, -0,050, -0,075 et -0.100 a ete utilise pour generer les ressauts. Une methode semi-empirique basee sur le principe de I'energie est presentee afin de prevoir la longueur des rouleaux. Les previsions basees sur la methode proposes concordent bien avec les resultals rapportes par les auteurs et d'autres chercheurs. II a ete demontre que la perte d'energie dans le ressaut hydraulique convent ion nel est superieure a celle de tout ressaut se formant sur des pentes negatives on positives. Mots-des : ressaut hydraulique, canal en pente, pente inverse, longueur de rouleau, perte d'energie. [Traduit par la Redaction], Introduction The hydraulic jump is widely used as an energy dissipater in the stilling basins of many hydraulic structures. The classical hydraulic jump occurring in a horizontal rectangular channel (the [...]

Plants and green algae maintain efficient photosynthesis under changing light environments by adjusting their light-harvesting capacity. It has been suggested that energy redistribution is brought about by shuttling the light-harvesting antenna complex II (LHCII) between photosystem II (PSII) and photosystem I (PSI) (state transitions), but such molecular remodeling has never been demonstrated in vivo. Here, using chlorophyll fluorescence lifetime imaging microscopy, we visualized phospho-LHCII dissociation from PSII in live cells of the green alga Chlamydomonas reinhardtii. Induction of energy redistribution in wild-type cells led to an increase in, and spreading of, a 250-ps lifetime chlorophyll fluorescence component, which was not observed in the stt7 mutant incapable of state transitions. The 250-ps component was also the dominant component in a mutant containing the light-harvesting antenna complexes but no photosystems. The appearance of the 250-ps component was accompanied by activation of LHCII phosphorylation, supporting the visualization of phospho-LHCII dissociation. Possible implications of the unbound phospho-LHCII on energy dissipation are discussed. photosynthesis | fluorescence lifetime imaging microscopy | green algae | light-harvesting | energy dissipation doi/10.1073/pnas.0908808107

The present experimental investigation focuses on energy dissipation and turbulence production in two undeveloped and a partially developed inflow weak hydraulic jumps, measured with micro-ADVs. For the undeveloped inflow jumps, the turbulence production is mostly confined in the shear layer located in the upper part of the water column. For the partially developed inflow jump, two peak turbulence production regions are observed, one in the upper shear layer and the second in the near-wall region. Moreover, the measured energy dissipation distribution in the jumps reveals a similar longitudinal decay of energy dissipation integrated over the flow sections and of maximum turbulence production values from the intermediate jump region toward its downstream section. DOI: 10.1061/(ASCE)HY.1943-7900.0000124 CE Database subject headings: Hydraulic jump; Turbulence; Inflow; Kinetics.

We investigate a two-level atom coupled to a cavity with a strong classical driving field in a dissipative environment and find an analytical expression for the time evolution density matrix for the system. The analytical density operator is then used to study the entanglement between the atom and cavity by considering the competing process between the atom-field interactions and the field-environment interactions. It is shown that there is an optimal interaction time for generating atom-cavity entanglement. PACS Nos: 03.67.-a, 42.50.Pq Nous etudions un atome a deux niveaux couple a une cavite avec un fort champ classique dans un environnement dissipatif et trouvons une expression analytique pour l'evolution temporelle de la matrice densite du systeme. Nous utilisons alors l'expression analytique de l'operateur densite pour etudier l'intrication entre l'atome et la cavite en considerant la competition entre les interactions atome-champ et les interactions champ-environnement. Nous montrons qu'il y a un temps d'interaction optimal pour generer l'intrication atome-cavite. [Traduit par la Redaction], 1. Introduction Quantum entanglement is one of the most striking features of quantum mechanics [1, 2]. It is central to many active research fields, such as quantum computation [3], quantum [...]

Charge generation in cross-linked polyethylene (XLPE) and ethylene propylene rubber (EPR) under dc stress are influenced strongly by inclusions. The inclusions influencing charge generation are cross-linking byproducts, antioxidants, and moisture. These inclusions particularly influence the generation of negative heterocharges observed near positive electrodes, which produce high electric stress regions in XLPE cable insulation under dc voltage. Because a high electric field might cause dielectric breakdown of high-voltage equipment, it is important to minimize negative heterocharge accumulation. Consequently, the authors performed experiments to clarify the negative heterocharge generation mechanism in XLPE and EPR. The authors first studied the influence of cross-linking byproduct and moisture on negative heterocharge generation to clarify the mechanism. The authors next performed experiments to elucidate the effect of antioxidants on heterocharge generation, which revealed that the negative heterocharge is generated in XLPE insulation containing sulfur-containing phenolic antioxidant, or sulfur-type antioxidant. This heterocharge is presumed to be created by the combined effect of the antioxidant and acetophenone. Furthermore, the authors studied the dissipation of negative heterocharges in XLPE and EPR, clarifying that the dissipation of negative heterocharges in EPR is much faster than that in XLPE. This paper presents results of these studies. Index Terms --Space charge, heterocharge, cross linked polyethylene, XLPE, ethylene propylene rubber, EPR, cross-linking byproduct, antioxidant, moisture, charge dissipation.

A very important limitation of high-speed analog-to-digital converters (ADCs) is their power dissipation. ADC power dissipation has been examined several times, mostly empirically. In this paper, we present an attempt to estimate a lower bound for the power of ADCs, based on first principles and using pipeline and flash architectures as examples. We find that power dissipation of high-resolution ADCs is bound by noise, whereas technology is the limiting factor for low-resolution devices. Our model assumes the use of digital error correction, but we also study an example on the power penalty due to matching requirements. A comparison with published experimental data indicates that the best ADCs use about 50 times the estimated minimum power. Two published ADCs are used for a more detailed comparison between the minimum bound and today's designs. Index Terms--Analog-digital conversion, CMOS analog integrated circuits, high-speed electronics, power demand.

In this paper, we investigated rotor iron loss of interior permanent magnet synchronous machine (IPMSM), which has distributed armature windings. In order to study the iron loss with the effect of slot-pole combination, two machines for high-speed operation such as electric vehicle were designed. One is fractional slot winding and the other is conventional one. In the analysis, we developed a new iron loss model of electrical machines for high-speed operation. The calculated iron loss was compared with the experimental data. It was clarified that the proposed method can estimate iron loss effectively at high-speed operation. Based on this newly proposed method, we analyzed iron loss of the two machines according to their driving conditions. From the analysis results, it was shown that rotor iron loss of machine employing fractional slot-winding is definitely large at load condition. In addition, it is interesting that the ratio (rotor iron loss/stator iron loss) becomes larger as the speed of the machines increase if the number of slot per pole is fractional. Index Terms--Distributed armature winding, electric vehicle, fractional slot per pole, high-speed, iron loss, interior permanent magnet synchronous machine.

In this paper, we set forth a procedure to perform detailed inductor designs using population-based optimization methods. We chose inductor designs on the basis of design inputs, i.e., the inductor geometry and core material. The method incorporates recent research in magnetic materials characterization, advanced inductor modeling, and hysteresis loss modeling. We present several case studies for both single- and multi-objective optimizations. Index Terms--Automated design, hysteresis, magnetic loss.

A quartz crystal microbalance (QCM) consists of a resonator, which measures the resonance frequency of the quartz slab. When coupled with a network analyzer or coupled with impulse excitation technology, QCM gives additional impedance or dissipation information, respectively. This report provides a set of equations that bring the QCM community a convergence of the dissipation and impedance analysis. Equations derived from the complex frequency shift were applied to quantitatively analyze the dissipation data of polymer brushes obtained from QCMD. The obtained viscoelastic properties of polymer brushes were then compared with those obtained by the Voigt model method. We believe that these equations will be useful in quantitative studies of interfacial phenomena accompanied with mass or viscoelasticity changes.

A novel setup was recently developed, combining quartz crystal microbalance with dissipation monitoring (QCM-D) and optical reflectometry for measurements on one and the same surface of, for example, biomolecular adlayers and interactions (Wang et al. Rev. Sci. Instr. 2008, 79 075107). This combination was chosen on the basis of prior experience of using QCM-D and optical techniques in separate instruments, which showed both the advantage of employing multiple techniques and the disadvantage of not working with the same surface and (flow) cell. The new instrument provides, for example, information about associated water and structural changes of the adlayers that would often pass unnoticed or be hard to interpret or quantify, using either technique alone. The triple response instrument (QCM-D frequency and dissipation and reflectometry) is here applied to four model systems: (A) formation of supported lipid bilayers (SLBs), (B) lipid exchange between a SLB and transiently adsorbed vesicles, (C) binding of a hydrated peptide on a functionalized SLB, and (D) streptavidin coupling to a biotinylated SLB, followed by attachment of biotinylated vesicles. The results demonstrate three major advantages of the combination instrument: (i) much faster data collection because the experiments are done on one surface for all signals, (ii) a common time axis and the same relative importance of surface kinetics and mass transport because the same liquid sample and the same transport conditions apply, and (iii) new features are discovered about the studied system that would be difficult to unravel in separate instruments.

The Principle of Maximum Dissipation Rate (PMD) can be exploited to derive homogeneous kinetic rate laws for the internal variables. A 'normality structure' expressing the rates of the internal variables as normal to convex functions (entropy production rate, dissipation function as flow potentials) in the space of the conjugate thermodynamic forces is a direct consequence of the PMD. This paper can be considered as a note to Yang et al., 2005, ASME J. Appl. Mech., 72, pp. 322-329. [DOI: 10.1115/1.2722304] Keywords: principle of maximum dissipation rate, normality structure, flow potentials, plasticity

This paper discusses an exact decomposition of the kinetic energy to determine the energy content that influences the dynamics of unilateral contacts in multibody systems. This decomposition essentially divides the kinetic energy of the whole multibody system into two completely decoupled parts associated with the constrained and admissible directions of unilateral contacts. This will provide a picture of how the energy absorption/ dissipation during impacts is related to the variation of the generalized velocities and the configuration of multibody systems. Potential applications of such a decoupling are highlighted. [DOI: 10.1115/1.2712226]

A method is developed and validated for the determination of approximate values of loss factors and frequencies of rectangular plates with general boundary conditions, fully covered on one side with a constrained layer damping treatment. The method, referred to as the method of equivalent lengths, is an extension for use on plates of the commonly used practice, through eigenvalue replacement, of applying the Ross, Ungar, and Kerwin analysis to the prediction of loss factors for beams with other than simply supported ends. Application of the method requires only that the modulus, thickness, and density of the substrate, constraining layer, and shear layer be known, as well as either the eigenvalue or natural frequency for the plate of aspect ratio and boundary condition to which the constrained layer treatment is to be applied. Predictions of the method are compared with results obtained by finite element methods for plates with various boundary conditions, including those with zero, one, two, three, and four free edges.

The effect of exogenous plastoquinone (PQ) on the different deexcitation pathways of photosystem I (PSI) is investigated. Reduction of the endogenous PQ pool in whole thylakoid membranes by NADPH increased photosystem I (PSI) fluorescence by 65%, indicating the importance of the redox state of the PQ pool on PSI energy dissipation.

The mechanism that nature applies to dissipate excess energy from solar UV light absorption in DNA is fundamental, because its efficiency determines the vulnerability of all genetic material to photodamage and subsequent mutations. Using femtosecond time-resolved broadband spectroscopy, we have traced the electronic excitation in both time and space along the base stack in a series of single-stranded and double-stranded DNA oligonucleotides. The obtained results demonstrate not only the presence of delocalized electronic domains (excitons) as a result of UV light absorption, but also reveal the spatial extent of the excitons. excitons | femtosecond | spectroscopy | photophysics

Anionic nanoparticles composed of two different materials with different sizes are produced and dispersed in aqueous solvents of various viscosities to distinguish mechanisms of magnetic energy dissipation. The analysis has helped in understanding the use of anionic colloidal nanocrystals to generate magnetically induced hyperthermia in various media, including complex systems and biological materials.

This paper employs dissipativity theory for the global analysis of limit cycles in particular dynamical systems of possibly high dimension. Oscillators are regarded as open systems that satisfy a particular dissipation inequality. It is shown that this characterization has implications for the global stability analysis of limit cycle oscillations: i) in isolated oscillators, ii) in interconnections of oscillators, and iii) for the global synchrony analysis in interconnections of identical oscillators. Index Terms--Global limit cycle analysis, global synchronization, Hopf and pitchfork bifurcations, networks of oscillators.

Mechanical energy dissipation in a micromechanical silicon resonator is sensitive to submonolayer changes in surface chemistry. These resonators terminated by a single monolayer of methyl groups have higher quality factors which then lower the rates of mechanical energy dissipation than comparable resonators terminated with either long-chain alkyl monolayers or hydrogen monolayers.

In the context of track reconstruction, the description of the material in a detector is frequently a simplified version of the detailed description used in the simulation. In particular, complex structures of different types of materials are often approximated by simple layers consisting of a material with average properties. Multiple scattering is then usually modeled by a Gaussian distribution, and energy loss by a narrow Gaussian or a delta function (Dirac distribution). More detailed information about the material can be taken into account by modeling multiple scattering and energy loss by mixtures of Gaussians and Dirac distributions, respectively. Each component of the mixture corresponds to a particular type of material, and the weight of the component is given by the probability to encounter this type of material. Track fitting using these mixtures can then be accomplished by the Gaussian-sum filter (GSF). Its performance is compared to a standard Kalman filter using the average material properties. The gain in precision of the estimated track parameters is studied in a series of simulation experiments, and the most promising scenarios are identified. Index Terms--Energy loss, Gaussian-sum filter (GSF), mixture model, multiple scattering, track reconstruction.

Space-grade Si and GaAs solar cells were irradiated with 15 & 40 MeV Li ions. Illuminated (AM0 condition) and unilluminated I-V curves reveal that the effect of high-energy Li ion irradiation has produced similar effects to that of proton irradiation. However, an additional, and different, defect mechanism is suggested to dominate in the heavier-ion results. Comparison is made with proton-irradiated solar-cell work and with non-ionizing energy-loss (NIEL) radiation-damage models. Index Terms--GaAs, ion-irradiation, lithium, NIEL, photovoltaic cells, radiation effects, silicon.

We compare differences in parametric degradation for CCDs irradiated to the same displacement damage dose with 2-MeV, 10-MeV, and 50-MeV electrons. Charge transfer efficiency degradation was observed to not scale well with non-ionizing energy loss (NIEL) for small signals. Short term annealing of mean dark current in a CCD sample irradiated with 2-MeV electrons at -85C is discussed, as well as additional annealing achieved by warming to temperatures up to and including room temperature. In contrast, charge transfer inefficiency was not observed to anneal following room temperature cycling for the sample irradiated at -85C. Index Terms--Annealing, CCD, displacement damage, electrons.

An analysis of the effects of low energy proton irradiation on the electrical performance of triple junction (3J) InGa[P.sub.2]/GaAs/Ge solar cells is presented. The Monte Carlo ion transport code SRIM is used to simulate the damage profile induced in a 3J solar cell under the conditions of typical ground testing and that of the omnidirectional space environment. The results are used to present a quantitative analysis of the defect, and hence damage, distribution induced in the cell active region by the different radiation conditions. The modeling results show that, in the space environment where the incident radiation is omnidirectional, the solar cell will experience a uniform damage distribution through the active region of the cell. The cases of directional spectrum irradiation and omnidirectional irradiation through very thin shielding are also considered. Through an application of the displacement damage dose analysis methodology, the implications of this result on mission performance predictions are investigated. Index Terms--Displacement damage, nonionizing energy loss, radiation effects, solar cells.

While calculated non-ionizing energy loss (NIEL) generally correlates well to first order with radiation-induced displacement damage rates, it does not account for some well-known differences in damage rates for n- and p-type Si. Here we show that the magnitude of these differences, [DELTA][K.sub.n-p], correlates closely with the fraction of total displacement damage due to low-energy primary knock-on atom (PKA) recoils. The primary products of these displacement damage events, with PKA recoils Index Terms--Density functional theory, displacement damage, electron traps, Frenkel pairs.

The retardation effect on the induced potentials was studied using a dielectric function with spatial dispersion for an electron of high energy moving parallel to the solid surface. It was found that the retardation effect was negligible for low-energy electrons but became important for high-energy electrons.

Parylene-C is a polymeric material primarily used in hybrid manufacturing for humidity protection and dielectric isolation. In this study, the influence of Parylene-C on passive millimeter-wave circuits such as transmission lines and resonators is investigated in electromagnetic simulations up to 100 GHz and measurements up to 67 GHz. It is demonstrated that when applying 5-[micro]m Parylene-C, the resonance frequency of a resonator is shifted 0.4% and the Q value is changed slightly. The dissipation factor of the Parylene-C versus frequency has been calculated from measured data. The flip-chip mounted broadband traveling-wave monolithic-microwave integrated-circuit (MMIC) amplifier is also investigated. A 5-[micro]m-thick Parylene-C coat results in a total loss of 1.04 dB. A positive side effect of the Parylene-C is that it allows heat, dissipated in the amplifier, to spread over a larger area, consequently lowering the backside temperature of the flipped MMIC with as much as 10 [degrees]C. The results from this study demonstrate that, concerning the electrical performance, Parylene-C is very well suited as protective coating in millimeter-wave applications and can be used as an alternative to a hermetic package in the frequency range from dc to 67 GHz to reduce weight and cost. Index Terms--Coatings, dielectric loss, dissipation factor, flip chip, humidity protection, monolithic microwave integrated circuits (MMICs), Parylene, poly-para-xylylene, resonators.

Abstract: An asphalt concrete damage-energy fatigue approach based on the concept of change in dissipated energy is presented in this paper. The damage-energy based fatigue approach is simple and based [...]

Electron energy balance is shown to play an important role in determining the plasma potential in low-density hot-filament discharges. The confined electrons that are lost to the walls are those with energy just above the plasma potential, thus the electron energy loss rate is the product of the electron loss rate and the height of the potential barrier. The sources of the electron energy are the energy at creation plus the energy gained from equilibration with energetic, unconfined electrons. An experiment in a soup-pot plasma device demonstrates that the plasma potential has values that satisfy the energy balance equation. The ion loss rate affects the electron loss rate through the quasi-neutrality condition, thus collisions of ions play a role in determining the plasma potential by reducing the particle loss rates. Index Terms--Plasma devices, plasma measurements, plasma sheaths.

Tethered balloon-borne measurements with a resolution in the order of 10 cm in a cloudy boundary layer are presented. Two examples sampled under different conditions concerning the clouds' stage of life are discussed. The hypothesis tested here is that basic ideas of classical turbulence theory in boundary layer clouds are valid even to the decimeter scale. Power spectral densities S(f) of air temperature, liquid water content, and wind velocity components show an inertial subrange behavior down to [approximately equal to]20 cm. The mean energy dissipation rates [bar.[epsilon]] are ~[10.sup.-3] [m.sup.2] [s.sup.-3] for both datasets. Estimated Taylor Reynolds numbers ([Re.sub.[lambda]]) are ~[10.sup.4], which indicates the turbulence is fully developed. The ratios between longitudinal and transversal S(f) converge to a value close to 4/3, which is predicted by classical turbulence theory for local isotropic conditions. Probability density functions (PDFs) of wind velocity increments [[DELTA].sub.u] are derived. The PDFs show significant deviations from a Gaussian distribution with longer tails typical for an intermittent flow. Local energy dissipation rates [[epsilon].sub.[tau]] are derived from subsequences with a duration of [tau] = 1 s. With a mean horizontal wind velocity of 8 m [s.sup.-1], [tau] corresponds to a spatial scale of 8 m. The PDFs of [[epsilon].sub.[tau]] can be well approximated with a lognormal distribution that agrees with classical theory. Maximum values of [[epsilon].sub.[tau]] [approximately equal to] [10.sup.-1] [m.sup.2] [s.sup.-3] are found in the analyzed clouds. The consequences of this wide range of [[epsilon].sub.[tau]] values for particle-turbulence interaction are discussed.

Block ramps or rock chutes are stream restoration structures used in many hydraulic projects. If the base material presents stability problems, a reinforcement can be used; it consists of placing over the ramp rocks greater in size than the base material in order to increase the flow resistance and reduce the shear stresses on the base material. The presence of these boulders also changes the energy dissipation of the flow over the structure. This work shows the results of experimental tests conducted on reinforced block ramps with slopes varying from 0.08 to 0.33. The effect of the various geometric parameters has been investigated. The aim is to extend existing relationships for a simple block ramp and define a new equation that can be applied to a block ramp with or without the presence of boulders. DOI: 10.1061/(ASCE)0733-9437(2006)132:3(293) CE Database subject headings: Ramps; Energy dissipation; Boulders; Riprap; Bed roughness.

We describe a series of computational experiments that employ nonoscillatory finite volume methods to simulate the decay of high Reynolds number turbulence. These experiments cover a broad range of physical viscosities and numerical resolutions. We have extracted a data set from these experiments detailing the energy dissipation by physical viscosity and by the numerical algorithm. We offer a preliminary analysis of this data, including new insights into the (computational) transition between direct numerical simulation and large eddy simulation. [DOI: 10.1115/1.2176749]

This paper presents analytic and experimental comparisons for high-efficiency class-F and inverse class-F amplifiers. The analytic formula of the efficiencies, output powers, dc power dissipations, and fundamental load impedances of both amplifiers are derived from the ideal current and voltage waveforms. Based on the formula, the performances are compared with a reasonable condition: fundamental output power levels of class-F and inverse class-F amplifiers are conditioned to be identical. The results show that the inverse class-F amplifier has better efficiency than that of class-F amplifiers as the on-resistance of the transistor increases. For experimental comparison, we have designed and implemented the class-F and inverse class-F amplifiers at 1-GHz band using a GaAs MESFET and analyzed the measured performances. Experimental results shows 10% higher power-added efficiency of the inverse class-F amplifier than that of the class-F amplifier, which verifies the waveform analysis. Index Terms--Class-F amplifier, harmonics control circuit, high-efficiency amplifier, inverse class-F amplifier, power amplifier.

A model is presented which makes it possible to predict power losses in a six-speed manual gearbox. The following sources of dissipation, i.e., power inputs in the model, are considered: (i) tooth friction. (ii) rolling element bearings; (iii) oil shearing in the synchronizers and at the shaft-free pinion inter, aces; and (iv) oil churning. Based upon the first principle of Thermodynamics for transient conditions, the entire gearbox is divided into humped elements with a uniform temperature connected by thermal resistances which account for conduction, convection, and radiation. The numerical predictions compare favorably with the efficiency measurements from the actual gearbox at different speeds and torques. The results also reveal that, at lower temperatures (about 40[degrees]C), power loss estimations cannot be disassociated from the accurate prediction of temperature distributions.