Holographic heat engine efficiency of hyperbolic charged black holes

We consider a four-dimensional charged hyperbolic black hole as working matter to establish a black hole holographic heat engine, and use the rectangular cycle to obtain the heat engine efficiency. We find that when the increasing of entropy is zero, the heat engine efficiency of the hyperbolic black hole becomes the well-known Carnot efficiency. We also find that less charge corresponds to higher efficiency in the case of $\tilde{q}>0$. Furthermore, we study the efficiency of the flat case and spherical case and compare the efficiency with that of the hyperbolic charged black holes. Finally, we use numerical simulation to study the efficiency in benchmark scheme.     

Motion and Efficiency of a Two-State Model for a Single Molecular Motor

We discussed the directed motion and the energy conversion efficiency of a particle in two-state ratchet potentials with white noise. We studied the effective potential of multi-state. The two-state potential is equivalent to an effective potential that has a nonzero average slope on a large scale in general. The incline of the effective potential is crucial to the directed motion and the efficiency. We also discussed the relationship between the efficiency and the kinetic parameters such as the strength of the noise and the transition rates between the two states. We notice that there exists a maximal efficiency when the noise strength and the fluctuating rates take appropriate values.     

Numerical analysis on the electrostatic capture of airborne nanoparticles and viruses in a homemade particle concentrator without a unipolar charger

A numerical analysis on the electrostatic capture of airborne viruses and nanoparticles in a homemade particle concentrator without a unipolar charger using commercial CFD software (CFD-ACE+) was presented. We simulated the effects of inlet/outlet configurations and particle diameters on the collection efficiency of the particle concentrator, and the simulation was in good agreement with the experimental measurements. We investigated the effects of the electrode arrangement on the collection efficiency. We also discussed the maximum collection efficiency and the relationship between the electric field intensity, the positions of the simulated particles on the inlet surface, and the collection efficiency.     

Metamaterial polarization converter analysis: limits of performance

In this paper, we analyze the theoretical limits of a metamaterial-based converter with orthogonal linear eigenpolarizations that allow linear-to-elliptical polarization transformation with any desired ellipticity and ellipse orientation. We employ the transmission line approach providing a needed level of the design generalization. Our analysis reveals that the maximal conversion efficiency for transmission through a single metamaterial layer is 50 %, while the realistic reflection configuration can give the conversion efficiency up to 90 %. We show that a double layer transmission converter and a single layer with a ground plane can have 100 % polarization conversion efficiency. We tested our conclusions numerically reaching the designated limits of efficiency using a simple metamaterial design. Our general analysis provides useful guidelines for the metamaterial polarization converter design for virtually any frequency range of the electromagnetic waves.     

Event-by-event efficiency fluctuations and efficiency correction for cumulants of superposed multiplicity distributions in relativistic heavy-ion collision experiments

We performed systematic studies on the effects of event-by-event efficiency fluctuations on efficiency correction for cumulant analysis in relativistic heavy-ion collision experiments. Experimentally, particle efficiencies of events measured under different experimental conditions should be different. For fluctuation measurements, the final event-by-event multiplicity distributions should be the superposed distributions of various type of events measured under different conditions. We demonstrate efficiency fluctuation effects using numerical simulation, in which we construct an event ensemble consisting of events with two different efficiencies. By using the mean particle efficiencies, we find that the efficiency corrected cumulants show large deviations from the original inputs when the discrepancy between the two efficiencies is large. We further studied the effects of efficiency fluctuations for the cumulants of net-proton distributions by implementing the UrQMD events of Au+Au collisions at sNN~(1/2) = 7.7 GeV in a realistic STAR detector acceptance. We consider the unequal efficiency in two sides of the Time Projection Chamber(TPC), multiplicity dependent efficiency, and the event-by-event variations of the collision vertex position along the longitudinal direction(V_z). When the efficiencies fluctuate dramatically within the studied event sample,the effects of efficiency fluctuations have significant impacts on the efficiency corrections of cumulants with the mean efficiencies. We find that this effect can be effectively suppressed by binning the entire event ensemble into various sub-event samples, in which the efficiency variations are relatively small. The final efficiency corrected cumulants can be calculated from the weighted average of the corrected factorial moments of the sub-event samples with the mean efficiencies.     

A new measure of network efficiency

We address the issue of the dynamical origin of scale-free link distributions. We study a two-dimensional lattice of cooperatively interacting units. Although the units interact only with the four nearest neighbors, a sufficiently large cooperation strength generates dynamically a scale-free network with the power law index ν approaching 1. We explain this result by using a new definition of network efficiency determined by the Euclidean distance between correlated units. According to this definition the link distribution favoring long-range connections makes efficiency increase. We embed an ad hoc scale-free network with power index ν≥1 into a Euclidean two-dimensional space and show that the network efficiency becomes maximal as ν approaches 1. We therefore conclude that ν=1 emerging from the cooperative interaction of units may be a consequence of the principle of network maximal efficiency.     

Low-power-pumped high-efficiency frequency doubling at 397.5 nm in a ring cavity

We report low pump power high-efficiency frequency doubling of a fundamental laser beam at 795 nm, corresponding to the rubidium D1 line, to generate UV light at 397.5 nm using a periodically poled KTi OPO4（PPKTP） crystal in a ring cavity. We obtain maximum stable output power of 49 m W for mode-matching pump power of 110 m W, corresponding to 45% raw efficiency（56% net efficiency when considering the output coupling mirror’s 80% transmission）. This is the highest efficiency obtained at this wavelength in PPKTP with such low pump power. We obtain 80% beam coupling efficiency to single-mode fiber, demonstrating high beam quality.     

Large-gap AC coplanar plasma display cells: macro-cell experiments and 3-D simulations

We present experimental and simulation studies of the plasma in a macroscopic AC plasma display panel discharge cell operating with a large coplanar gap. We find that the xenon excitation efficiency is much larger than that in the conventional, small-gap electrode configuration but with larger sustaining voltage. We discuss the discharge mode and efficiency in such large gap configurations, with the help of time resolved optical diagnostics and simulations.     

Increasing thermoelectric efficiency: a dynamical systems approach

Inspired by the kinetic theory of ergodic gases and chaotic billiards, we propose a simple microscopic mechanism for the increase of thermoelectric efficiency. We consider the cross transport of particles and energy in open classical ergodic billiards. We show that, in the linear response regime, where we find exact expressions for all transport coefficients, the thermoelectric efficiency of ideal ergodic gases can approach the Carnot efficiency for sufficiently complex charge carrier molecules. Our results are clearly demonstrated with a simple numerical simulation of a Lorentz gas of particles with internal rotational degrees of freedom.     

Waveguide second-harmonic generation device with broadened flat quasi-phase-matching response by use of a grating structure with located phase shifts

We report on a theoretical analysis and experiments for bandwidth broadening in quasi-phase-matched (QPM) second-harmonic generation (SHG).We used phase-shifted segments of a periodic grating to obtain a spectrally broadened, nearly flat response simultaneously with high conversion efficiency. We used an x-cut MgO:LiNbO(3) QPM waveguide in our analysis and experiments. The spectral range of the 850-nm fundamental for which SHG conversion exceeded 0.95 of the maximum value broadened from 0.02 to 0.12 nm when a 1-cm-long grating was divided into three segments with optimum phase shift. SHG conversion efficiency was 300%/W for this waveguide. The SHG efficiency and phase-matching characteristics showed good agreement with theoretical results.     

Interconvertibility of single-rail optical qubits

We show how to convert between partially coherent superpositions of a single photon with the vacuum by using linear optics and postselection based on homodyne measurements. We introduce a generalized quantum efficiency for such states and show that any conversion that decreases this quantity is possible. We also prove that our scheme is optimal by showing that no linear optical scheme with generalized conditional measurements, and with one single-rail qubit input, can improve the generalized efficiency.     

Quantum estimation of detection efficiency with no-knowledge quantum feedback

We investigate that no-knowledge measurement-based feedback control is utilized to obtain the estimation precision of the detection efficiency. We show that no-knowledge measurement is the optimal way to estimate the detection efficiency.The higher precision can be achieved for the lower or larger detection efficiency. It is found that no-knowledge feedback can be used to cancel decoherence. No-knowledge feedback with a high detection efficiency can perform well in estimating frequency and detection efficiency parameters simultaneously; simultaneous estimation is better than independent estimation given by the same probes.     

Diffraction efficiency of localized holograms in doubly doped LiNbO(3) crystals

The diffraction efficiency of M holograms superimposed in the volume of the recording medium is proportional to 1/M(2). We present a method, based on nondestructive localized holograms in a doubly doped LiNbO(3) crystal, that allows us to also record M holograms in the same volume without an exposure schedule or a diffraction efficiency that has 1/M dependence. We compare experimentally the final diffraction efficiency obtained with the localized and distributed recording methods.     

有机PIN型太阳能电池的数值模拟

从有机太阳能电池的工作机理出发,给出了有机P-I-N型有机太阳电池的理论模型,并对模型的激子产生率和载流子浓度分布进行了数值模拟,分析了光强和载流子迁移率对电池效率的影响,为高效率的此类电池的设计提供了理论依据。     

Toward textbook multigrid efficiency for fully implicit resistive magnetohydrodynamics

Multigrid methods can solve some classes of elliptic and parabolic equations to accuracy below the truncation error with a work-cost equivalent to a few residual calculations – so-called “textbook” multigrid efficiency. We investigate methods to solve the system of equations that arise in time dependent magnetohydrodynamics (MHD) simulations with textbook multigrid efficiency. We apply multigrid techniques such as geometric interpolation, full approximate storage, Gauss–Seidel smoothers, and defect correction for fully implicit, nonlinear, second-order finite volume discretizations of MHD. We apply these methods to a standard resistive MHD benchmark problem, the GEM reconnection problem, and add a strong magnetic guide field, which is a critical characteristic of magnetically confined fusion plasmas. We show that our multigrid methods can achieve near textbook efficiency on fully implicit resistive MHD simulations.     

Tunable solid-state laser based on MPMMA co-doped with Pyrromethene 567 and Rhodamine 610

We study laser performance with two laser dyes, Pyrromethene 567 and Rhodamine 610, co-doped into modified poly(methyl methacrylate) (MPMMA). We achieve a more than 37 nm wide tunable range. We obtain a narrowband-laser slope efficiency of 27.24%, which is almost as high as a broadband-output slope efficiency of 36.6%. To the best of our knowledge, the narrowband slope efficiency is the highest under the same conditions so far. The narrowband laser linewidth obtained is far less than 0.3 nm. All our results indicate that high laser performance can be achieved using two dyes co-doped into MPMMA.     

Efficiency bounds for nonequilibrium heat engines

We analyze the efficiency of thermal engines (either quantum or classical) working with a single heat reservoir like an atmosphere. The engine first gets an energy intake, which can be done in an arbitrary nonequilibrium way e.g. combustion of fuel. Then the engine performs the work and returns to the initial state. We distinguish two general classes of engines where the working body first equilibrates within itself and then performs the work (ergodic engine) or when it performs the work before equilibrating (non-ergodic engine). We show that in both cases the second law of thermodynamics limits their efficiency. For ergodic engines we find a rigorous upper bound for the efficiency, which is strictly smaller than the equivalent Carnot efficiency. I.e. the Carnot efficiency can be never achieved in single reservoir heat engines. For non-ergodic engines the efficiency can be higher and can exceed the equilibrium Carnot bound. By extending the fundamental thermodynamic relation to nonequilibrium processes, we find a rigorous thermodynamic bound for the efficiency of both ergodic and non-ergodic engines and show that it is given by the relative entropy of the nonequilibrium and initial equilibrium distributions. These results suggest a new general strategy for designing more efficient engines. We illustrate our ideas by using simple examples.     

Efficient femtosecond optical parametric oscillators based on aperiodically poled nonlinear crystals

We discuss the use of aperiodically poled nonlinear crystals to improve conversion efficiency in a synchronously pumped ultrafast optical parametric oscillator. We show theoretically that with these crystals the conversion efficiency can be considerably higher than that obtained when a periodically poled crystal with the same length is used. Moreover, we show that pump threshold can be simultaneously improved by use of longer crystals.