Constraining cosmological parameters with observational data including weak lensing effects

In this Letter, we study the cosmological implications of the 100 square degree Weak Lensing survey (the CFHTLS-Wide, RCS, VIRMOS-DESCART and GaBoDS surveys). We combine these weak lensing data with the cosmic microwave background (CMB) measurements from the WMAP5, BOOMERanG, CBI, VSA, ACBAR, the SDSS LRG matter power spectrum and the Type Ia Supernoave (SNIa) data with the “Union” compilation (307 sample), using the Markov Chain Monte Carlo method to determine the cosmological parameters, such as the equation-of-state (EoS) of dark energy w  , the density fluctuation amplitude σ₈${\sigma }_8$, the total neutrino mass ∑mν$\sum m_{\nu }$ and the parameters associated with the power spectrum of the primordial fluctuations. Our results show that the ΛCDM model remains a good fit to all of these data. In a flat universe, we obtain a tight limit on the constant EoS of dark energy, w=−0.97±0.041$w=-0.97\pm 0.041$ (1σ  ). For the dynamical dark energy model with time evolving EoS parameterized as wde(a)=w₀+wa(1−a)$w_{\mathrm{de}}(a)=w_0+w_a(1-a)$, we find that the best-fit values are w₀=−1.064$w_0=-1.064$ and wa=0.375$w_a=0.375$, implying the mildly preference of Quintom model whose EoS gets across the cosmological constant boundary during evolution. Regarding the total neutrino mass limit, we obtain the upper limit, ∑mν<0.471 eV$\sum m_{\nu }<0.471\text{eV}$ (95% C.L.) within the framework of the flat ΛCDM model. Due to the obvious degeneracies between the neutrino mass and the EoS of dark energy model, this upper limit will be relaxed by a factor of 2 in the framework of dynamical dark energy models. Assuming that the primordial fluctuations are adiabatic with a power law spectrum, within the ΛCDM model, we find that the upper limit on the ratio of the tensor to scalar is r<0.35$r<0.35$ (95% C.L.) and the inflationary models with the slope ns?1$n_s?1$ are excluded at more than 2σ   confidence level. In this Letter we pay particular attention to the contribution from the weak lensing data and find that the current weak lensing data do improve the constraints on matter density Ωm${\Omega }_m$, σ₈${\sigma }_8$, ∑mν$\sum m_{\nu }$, and the EoS of dark energy.     

Electrostatic forces in micromanipulation: Experimental characterization and simulation including roughness

Manipulation by contact of objects between 1 m and 1 mm are often disturbed by adhesion between the manipulated object and the gripper. Electrostatic forces are among the phenomena responsible for this adhesive effect. Analytical models have been developed in the literature to predict electrostatic forces. Most models have been developed within the framework of scanning probe microscopy, i.e. for a contact between a conducting tip and a metallic surface. In our study, we developed a simulation tool based on finite elements modeling. The strength of this model lies in the fact that it integrates roughness parameters. Measurements of electrostatic forces in function of roughness were conducted by atomic force microscopy. The experimental results were compared with the simulation results showing very good correlation. This demonstrates the influence of surface topography on electrostatic forces, especially for very small separation distances and proves the utility of the simulation tool in designing surfaces with controlled adhesion. Some application fields to which these results can be applied are drug delivery devices and micromanipulation tools.     

Electrostatic forces in micromanipulations: Review of analytical models and simulations including roughness

Manipulations by contact of objects between 1 m and 1 mm are often disturbed by adhesion between the manipulated object and the gripper. Electrostatic forces are among the phenomena responsible for this adhesive effect. Analytical models have been developed in the literature to predict the electrostatic forces. Most models are developed within the framework of scanning probe microscopy, i.e. for a contact between a conducting tip and a metallic surface. Models are reviewed in this work and compared with our own simulations using finite elements modeling. The results show a good correlation. The main advantage of our simulations lies in the fact that they can integrate roughness parameters. For this purpose, a fractal representation of the surface topography was chosen through the use of the Weierstrass-Mandelbrot function. Comparisons with experimental benchmarks from the literature show very good correlation between experimental results and simulations. It demonstrates the importance of surface topography on electrostatic forces at very close separation distances.     

Determination of dispersion curve parameters from transient wave

The wave properties of dispersive media can be easily investigated by introducing an impulse disturbance into the medium and recording the development of the resulting wave phenomenon in time and space. The types of diagrams thus obtained are classified and a practical method of their evaluation is described. As a numerical example, a diagram of the stratification wave in a discharge plasma is evaluated.In conclusion the authors would like to express their gratitude to O. Stirand and V. Simák for helpful discussion.     

Simulation of electromechanical coupling coefficient by modified modal frequency spectrum method including the electrode effect

An approximate formula has been developed to determine the electromechanical coupling coefficient of the piezoelectric film in a four-layer composite resonator, which includes two electrodes. In this formula, the coupling coefficient can be calculated from the distribution of the effective coupling coefficients, k2eff, which are given by the modal frequency spectrum of the composite resonator. The feasibility of this method has been demonstrated with a ZnO/SiO2 composite resonator for different electrode thickness. The effect of mechanical propagation loss in both piezoelectric layer and substrate has also been studied.     

Calculation of proton-deuteron phase parameters including the coulomb force

A previously proposed exact method for including the Coulomb force in three-body collisions is applied to proton-deuteron scattering. We present phase shifts for angular momenta up to L = 9, from elastic threshold to 50 MeV proton laboratory energy. Separable rank-one potentials are taken for the nuclear interactions. A charge-independent and a charge-symmetric choice, while leading to different neutron-deuteron and proton-deuteron phase parameters, nevertheless yield practically the same Coulomb corrections. We investigate, moreover, the question of P-wave resonances. A critical comparison of our results with those obtained in a coordinate-space formalism is performed. Furthermore, proposals for an approximate inclusion of the Coulomb potential are tested, and found unsatisfactory.     

Determination of modal parameters from off-diagonal FRFs using the double-exponential windowing method

In a recently published paper (Sheng, 2012) [1], the double-exponential windowing method has been developed for the determination of modal parameters for lightly damped structures. This method, like many others, requires the driving-point frequency response function (FRF) to be measured. However, this requirement is sometimes practically hard to meet, especially when the structure is small, since it is difficult, if not impossible, to avoid interference between the force transducer and the laser beam as a response pick-up, thus limiting the usefulness of the method. To overcome this shortcoming, an alternative is therefore developed in this paper: a similar process but without requiring the measuring of any driving-point FRF.     

Interval analysis of transient temperature field with uncertain-but-bounded parameters

Based on the traditional finite volume method, a new numerical technique is presented for the transient temperature field prediction with interval uncertainties in both the physical parameters and initial/boundary conditions. New stability theory applicable to interval discrete schemes is developed. Interval ranges of the uncertain temperature field can be approximately yielded by two kinds of parameter perturbation methods. Different order Neumann series are adopted to approximate the interval matrix inverse. By comparing the results with traditional Monte Carlo simulation, a numerical example is given to demonstrate the feasibility and effectiveness of the proposed model and methods.     

Non-equilibrium thermodynamics of interfaces including electromagnetic effects

The application of non-equilibrium thermodynamics to a system consisting of two bulk phases and their interface is extended to include electromagnetic effects. The interface is assumed to carry singular mass, energy, and entropy densities as well as singular electric charge, electric current, polarization and magnetization. Electric and magnetic fields are allowed to be discontinuous across the interface, but not singular.Maxwell's equations are used to derive relationships among electromagnetic quantities on the surface and boundary conditions for the bulk phases. An expression for the surface entropy production including electromagnetic effects is obtained, and the resulting linear laws relating thermodynamic forces and fluxes are investigated.     

Numerical and experimental analysis of uncertainty on modal parameters estimated with the stochastic subspace method

Modal parameters of structures are often used as inputs for finite element model updating, vibration control, structural design or structural health monitoring (SHM). In order to test the robustness of these methods, it is a common practice to introduce uncertainty on the eigenfrequencies and modal damping coefficients under the form of a Gaussian perturbation, while the uncertainty on the mode shapes is modeled in the form of independent Gaussian noise at each measured location. A more rigorous approach consists however in adding uncorrelated noise on the time domain responses at each sensor before proceeding to an operational modal analysis. In this paper, we study in detail the resulting uncertainty when modal analysis is performed using the stochastic subspace identification method. A Monte-Carlo simulation is performed on a simply supported beam, and the uncertainty on a set of 5000 modal parameters identified with the stochastic subspace identification method is discussed. Next, 4000 experimental modal identifications of a small clamped–free steel plate equipped with 8 piezoelectric patches are performed in order to confirm the conclusions drawn in the numerical case study. In particular, the results point out that the uncertainty on eigenfrequencies and modal damping coefficients may exhibit a non-normal distribution, and that there is a non-negligible spatial correlation between the uncertainty on mode shapes at sensors of different locations.     

Precise determination of Mössbauer lineshape parameters including interference

Using 100 Ci¹⁸³Ta and 5 Ci¹⁸²Ta sources, with LiF and NaCl crystal monochromating filters, we have measured the lineshape parameters for the 46.5 keV and 99.1 keV Mossbauer effect (ME) transitions of¹⁸³W and the 100.1 keV transition of¹⁸²W. Using an analytic representation of the convolution integral and utilizing asymptotic analyses of the lineshape, we find, for both transmission and microfoil internal conversion (MICE) experiments, accurate values of all ME parameters including width, position, cross section, and interference. This new approach allows deconvolution of source and absorber spectra and gives a simple analytic expression for both as well as their Fourier transforms. The line widths for the 46.5, 99.1, and 100.1 keV transitions are 3.10(10), 0.369(18), and 0.195(12) cm/s, respectively. The interference parameters are –0.00257(9), –0.0093(12), and –0.0107(12) in the same respective order. The agreement between transmission and MICE /1,2/ measurements for the above lineshape parameters is within the experimental errors. We believe these measurements are the first having sufficient precision to allow a quantitative comparison with dispersion theory /3,4/ and they indicate interference parameters 10 to 20% smaller than predicted. Our measured line widths are less than earlier reported values. This is because our analysis of the true lineshape and the study of line asymptotics permits a quantitative determination of the isomer lifetimes rather than the usual lower bound found in earlier ME experiments.This material was prepared with the support of the U.S. Department of Energy, Grants No. DE-FG02-85 ER 45199 A00 and De-FG02-85 ER 45200.     

The effect of calibrated nonlocal constant on the modal parameters and stability of axially compressed CNTs

Nowadays investigating the vibration behavior of carbon nanotubes (CNTs) has drawn considerable attention due to the superior mechanical properties of the CNTs. One of the powerful theoretical methods to study the vibration behavior of CNTs is implementing the nonlocal theory. Most of studies on the vibration behavior of CNTs have assumed a fixed value for small scale parameter for all vibration modes, however, this value is mode-dependent. Therefore, in this paper, the small scale parameter is calibrated for a single-walled carbon nanotube (SWCNT) with respect to each vibration mode. For this propose, the governing equation of motion based on the nonlocal beam theory is extracted by applying the Hamilton's principle. Then, by using the power series method, an eigenvalue problem is defined to derive the calibrated value of small scale constant and nonlocal mode shapes of the CNT. By using the expansion theory, the equation of motion is discretized, and the effect of nonlocality on the modal parameters and stability of the CNT under compressive force is investigated. Finally, the possibility of estimating nonlocal parameter based on simulated frequency domain response of the system by using modal analysis methods is studied. The results show that the calibration of small scale constant is important and the critical axial force is highly sensitive to this value.     

Experimental measurement of dynamic crack-tip stress-field parameters under transient loading

The asymptotic stress field near the tip of a transient crack is examined. It is shown that the transient terms become important in determining the stress state only if their magnitude exceeds a certain material-dependent value; below this, a lower-order analysis is shown to be appropriate. The implications of this on experimental measurements and on fracture characterization are examined.     

The flux distribution and hysteresis losses in highT c superconductors including viscous forces on flux lines

By comparing the contributions of pinning and viscous forces to the restoring force on flux ines in type II and highT _c superconductors, it is shown that the flux flow in highT _c superconducto rs should play an important role in determining the magnetic flux distribution and hence the hyste resis losses in a.c. fields. Both quantities are calculated in the extreme case of very large viscous forces with respect to the pinning force. The magnetic field and frequency dependence of the losses are changed with respect to the results obtained from the critical state model. The theoretical results are qualitatively confirmed by a.c. susceptibility measurements at different magnetic field amplitudes and frequencies. The quantitative differences indicate that the flux flow effects in highT _c superconductors are by far not so strong as expected and supposed by some theories. The reasons for these discrepancies are discussed.     

Reduction of seismic forces on existing buildings with newly constructed additional stories including friction layer and dampers

This paper presents a new approach to improve seismic readiness of story-increased buildings by utilizing passive structure control techniques. This approach uses passive structural control techniques such as sliding-friction layer and dampers. The sliding-friction layer is sandwiched between the bottom surface of the increased structure and the rooftop of the original building. The energy dissipation dampers are installed between the supporting outer frame for the increased-structure and each floor of the original buildings. To assist dynamic analysis and control design, a simplified structural model of the building system is derived. To increase computational accuracy and to reduce computation time, a novel Coulomb friction representation is incorporated into the non-linear dynamic analysis. The proposed method is applied to a story-increased building and numerical results demonstrate the effectiveness of the proposed method.     

Analytic description of optical bistability including spatial effects

Steady-state features for both absorptive and dispersive bistability are obtained analytically with the inclusion of spatial effects. Both Fabry-Perot and ring-cavity geometries are treated using an analytic integration of coupled field equations for counter-propagating waves in a homogeneously broadened two-level medium. The mean-field limit is rigorously introduced starting from exact solutions. Mean-field state equations for both Fabry-Perot and ring cavities are obtained. In the former case explicit comparisons are made with results arising in the approximate treatment of standing waves.