Agitated behavior and elastic characteristics of pedestrians in an alternative floor field model for pedestrian dynamics

An alternative floor field (FF) model is proposed by incorporating the agitated behavior and elastic characteristics of pedestrians. The agitated behavior which is regarded as an important factor to pedestrian dynamics is depicted by introducing a parameter to revise the transition probability of pedestrians to move to the neighboring cells. To characterize elasticity of pedestrians, it is assumed that a cell can hold more than one pedestrians in crowd condition, while it can hold only one pedestrian in normal condition. In addition, a method to deal with conflicts is employed by considering the effects of agitated behavior and desired velocity. Numerical simulations are carried out to investigate pedestrian evacuation from a room. The results show, that as the value of agitated parameter increases, the evacuation time decreases to the minimum value and then increases gradually. Also, the faster-is-slower effect which is obtained by some other simulation models can be reproduced by the proposed model. Finally, the influence of exit width and the corresponding mechanism on evacuation process is investigated which is expected to be helpful to the exit design of public rooms.     

Period tripling causes rotating spirals in agitated wet granular layers

Pattern formation of a thin layer of vertically agitated wet granular matter is investigated experimentally. Rotating spirals with three arms, which correspond to the kinks between regions with different colliding phases, are the dominating pattern. This preferred number of arms corresponds to period tripling of the agitated granular layer, unlike predominantly subharmonic Faraday crispations in dry granular matter. The chirality of the spatiotemporal pattern corresponds to the rotation direction of the spirals.     

Hydraulic theory for a debris flow supported on a collisional shear layer

We consider a heap of grains driven by gravity down an incline. We assume that the heap is supported at its base on a relatively thin carpet of intensely sheared, highly agitated grains that interact through collisions. We adopt the balance laws, constitutive relations, and boundary conditions of a kinetic theory for dense granular flows and determine the relationship between the shear stress, normal stress, and relative velocity of the boundaries in the shear layer in an analysis of a steady shearing flow between identical bumpy boundaries. This relationship permits us to close the hydraulic equations governing the evolution of the shape of the heap and the velocity distribution at its base. We integrate the resulting equations numerically for typical values of the parameters for glass spheres. (c) 1999 American Institute of Physics.     

Minority persistence in agent based model using information and emotional arousal as control variables

We present detailed analysis of the behavior of an agent based model of opinion formation, using a discrete variant of cusp catastrophe behavior of single agents. The agent opinion about a particular issue is determined by its information about the issue and its emotional arousal. It is possible that for agitated agents the same information would lead to different opinions. This results in a nontrivial individual opinion dynamics. The agents communicate via messages, which allows direct application of the model to ICT based communities. We study the dependence of the composition of an agent society on the range of interactions and the rate of emotional arousal. Despite the minimal number of adjustable parameters, the model reproduces several phenomena observed in real societies, for example nearly perfectly balanced results of some highly contested elections or the fact that minorities seldom perceive themselves to be a minority.     

Density inversion in rapid granular flows: the supported regime

This paper presents numerical findings on rapid 2D and 3D granular flows on a bumpy base. In the supported regime studied here, a strongly sheared, dilute and agitated layer spontaneously appears at the base of the flow and supports a compact packing of grains moving as a whole. In this regime, the flow behaves like a sliding block on the bumpy base. In particular, for flows on a horizontal base, the average velocity decreases linearly in time and the average kinetic energy decreases linearly with the travelled distance, those features being characteristic of solid-like friction. This allows us to define and measure an effective friction coefficient, which is independent of the mass and velocity of the flow. This coefficient only loosely depends on the value of the micromechanical friction coefficient whereas the infuence of the bumpiness of the base is strong. We give evidence that this dilute and agitated layer does not result in significantly less friction. Finally, we show that a steady regime of supported flows can exist on inclines whose angle is carefully chosen.     

Low temperature transport study of C60 thin film FETs

Low temperature transport in C₆₀ thin film field-effect transistors has been studied using several samples with various gate voltages. Nearest neighbor hopping and variable range hopping transport have been observed in the low temperature transport measurements. Analyzing the temperature dependence of the transport types, it was found that the electrical properties of the film can be improved by thermally agitated evaporation of C₆₀.     

Gravitation and Riemannian space

The field equations of the quadratic action principle of relativity are solved, assuming a weak perturbation of the basic structure, which is a highly agitated Riemannian lattice field of a very small lattice constant. A field emerges which can be interpreted as the weak gravitational field of an apparently Minkowskian space. This field does not coincide with Einstein's theory of weak gravitational fields. Whereas the redshift remains unchanged, the light deflection becomes reduced by11.1% of the value predicted by Einstein.     

Exact analytic formulae for the correlation times for single domain ferromagnetic particles

Exact solutions for the longitudinal relaxation time T_∥ and the complex susceptibility χ_∥(ω) of a thermally agitated single domain ferromagnetic particle are presented for the simple uniaxial (Maier-Saupe) potential of the crystalline anisotropy considered by Brown [Phys. Rev. 130 (1963) 1677].     

New agitated and thermostatized cell for in situ monitoring of fast reactions by synchrotron SAXS

A thermostatized and agitated sample cell for synchrotron small‐angle X‐ray scattering (SAXS) measurements of liquid samples (homogeneous or heterogeneous) has been developed. The cell is composed of a compact main body with inlet and outlet windows for the beams of light. The volume of the cell is approximately 0.8 ml and the distance between the windows is 5 mm to allow accurate SAXS measurements. The cell is thermostatized by means of a jacket that surrounds the sample holder and it is connected to a thermostatic bath. In addition, the cell has a top and a bottom lid that allow easy cleaning and maintenance without demounting the optical windows. The cell has been used to run SAXS measurements of liquid samples and, for the first time, a mini‐emulsion polymerization reaction has been monitored by SAXS.     

Active nematics are intrinsically phase separated

Two-dimensional nonequilibrium nematic steady states, as found in agitated granular-rod monolayers or films of orientable amoeboid cells, were predicted [Europhys. Lett. 62, 196 (2003)10.1209/epl/i2003-00346-7] to have giant number fluctuations, with the standard deviation proportional to the mean. We show numerically that the steady state of such systems is macroscopically phase separated, yet dominated by fluctuations, as in the Das-Barma model [Phys. Rev. Lett. 85, 1602 (2000)10.1103/PhysRevLett.85.1602]. We suggest experimental tests of our findings in granular and living-cell systems.     

Experimental study on off-axis scattering of flat top partially coherent laser beams when propagating under water in the presence of moving scatterers

Off-axis underwater scattering of spatially partially coherent Multi-Gaussian Schell-Model (MGSM) beams are compared with fully coherent Gaussian beams in both a stationary setting and in the presence of mechanically agitated scatterers in underwater environments. The analysis is carried out by comparing the mean intensities of scattered light, the normalized variance, and the scintillation index in various scenarios. Results indicate that fully coherent beams have increased off-axis scattered light variations in the presence of moving scatterers as compared with a spatially partially coherent MGSM beam. Additionally, in a stationary environment the coherent beam has less overall variations as expected due to the nature of constructing partially coherent MGSM beams. Metrics of normalized variance, scintillation index, and overall average intensity are discussed in the context of potential beam localization, reduced scattering, and off-axis detection.     

Electrical characterization of high-k gate dielectrics on semiconductors

This paper reviews the following electrical characterization techniques for measuring the microscopic bonding structures, impurities, and electrically active defects in advanced CMOS gate stacks: (1) inelastic electron tunneling spectroscopy (IETS), (2) lateral profiling of threshold voltages, interface-trap density, and oxide charge density distributions along the channel of a MOSFET, and (3) pulse agitated substrate hot electron injection (PASHEI) technique for measuring trapping effects in the gate dielectric at low and modest gate voltages.     

Steady large-scale modulation of a moderately turbulent co-flow jet

The effects of a spatial modulation acting at the inflow of a moderately turbulent planar jet surrounded by a faster co-flow are investigated using direct numerical simulation of the Navier–Stokes equations. We adopt a superposition of spatially filtered small-scale random perturbations and a structured large-scale flow modulation. The large-scale modulation is characterised in terms of a Beltrami flow, specified by a wavenumber K. These large-scale modulations are steady and spatially periodic, while the random small-scale perturbations fluctuate in time and in space. The flow configuration studied in this paper is agitated by this combined large- and small-scale agitation at the inflow plane of a rectangular domain of size L × L × 2L in the x-, y- and streamwise z-directions. The inflow perturbation is focused on a strip of size L × D in the x- and y-directions. A parametric variation is carried out considering different choices for the wavenumber of the large-scale modulation. We focus on effects that the inflow modulation has on global characteristics of the flow, e.g. the width of the mixing region formed between the two streams and the dissipation rate, ?. Results show that the width of the mixing region increases faster compared to the case without the large-scale perturbation, when the flow is agitated by structures of size comparable to the integral scales of the flow. For the dissipation rate, results show the presence of a maximum response at a certain wavenumber K in case we apply a large-scale modulation. This maximum is attained at modulation scales that vary locally with respect to the distance from the inflow plane. Close to the inflow, the maximum response occurs at small modulation scales, while further into the domain a maximum response is present at comparably large modulation scales.     

Dynamics of a domain wall coupled to thermally agitated spins: A model of a rare earth ferrite-garnet

The nonlinear mobility of a domain wall in an idealized model of a RE ferrite-garnet is considered, the thermally agitated RE sublattice being described by the Landau-Lifshitz-Bloch equation [4] with longitudinal relaxation terms. It is shown that in some field intervals the DW velocity is small and governed by the longitudinal relaxation of the RE ions. This effect may be observed in sufficiently low magnetic fields near the compensation point of ferrites. If the dynamics of the RE spins is dissipationless, there is a non-analytic contribution to the DW damping due to the wake in the RE subsystem.     

Dynamic forces on agglomerated particles caused by high-intensity ultrasound

In this paper the acoustic forces on particles and agglomerates caused by high-intensity ultrasound in gaseous atmosphere are derived by means of computational fluid dynamics (CFD). Sound induced forces cause an oscillating stress scenario where the primary particles of an agglomerate are alternatingly pressed together and torn apart with the frequency of the applied wave. A comparison of the calculated acoustic forces with respect to the inter particle adhesion forces from Van-der-Waals and liquid bridge interactions reveals that the separation forces may reach the same order of magnitude for 80 μm sized SiO₂-particles. Hence, with finite probability acoustically agitated gases may de-agglomerate/disperse solid agglomerate structures. This effect is confirmed by dispersion experiments in an acoustic particle levitation setup.     

Topological flow characteristics in a butterfly valve used for a spark ignition engine

The flow fields in a butterfly valve, consisting of a circular cylinder and a circular plate with a circular shaft, are numerically investigated with changing the valve angle, i.e., 15°, 45°, 75° and 90°(full-open). The corresponding Reynolds numbers are chosen as 10⁴, 4 × 10⁴, 7 × 104, and 10⁵. The pressure drops between the entrance and the exit of the valve are 0.904, 0.575, 0.382 and 0.199, respectively at the above four valve positions. The moment coefficients calculated for the valve shaft are mostly due to the unbalanced pressure distribution on the both sides of the valve plate and -0.365, -0.082, -0.033 and 0, respectively, for each valve angle. The pressure distribution on the valve cylinder and the topological streamline patterns qualitatively show the flow field exceedingly agitated by the valve plate and its shaft.     

In-line FBRM Monitoring of Particle Size in Dilute Agitated Suspensions

The use of laser light scattering technology, as applied by the Focused Beam Reflectance Measurement (FBRM) probe from Lasentec, for the in-line monitoring of particle size was investigated. In particular, the effects of probe position and orientation were studied for a dilute agitated aqueous particulate suspension of known particle size distribution in a number of vessels. In all cases, the normalised chord length distribution recorded with the FBRM system was consistent with the theoretically predicted distribution. However, the total number of counts measured was a function both of solids concentration and probe location. Optimum probe location is dependent on the ease with which the solid phase can be suspended with the available agitation system and on the associated dominant flow direction within the vessel.     

Nano-meter-sized domain formation in lipid membranes observed by small angle neutron scattering

Using a contrast matching technique of small angle neutron scattering (SANS), we have investigated a phase separation to liquid-disordered and liquid-ordered phases on ternary small unilamellar vesicles (SUVs) composed of deuterated-saturated, hydrogenated-unsaturated phosphatidylcholine lipids and cholesterol, where the equilibrium size of these domains is constrained to less than 10nm by the system size. Below a miscibility temperature, we observed characteristic scattering profiles with a maximum, indicating the formation of nano-meter-sized domains on the SUVs. The observed profiles can be described by a multi-domain model rather than a mono-domain model. The nano-meter-sized domain is agitated by thermal fluctuations and eventually ruptured, which may result in the multi-domain state. The kinetically trapped nano-meter-sized domains grow to a mono-domain state by decreasing temperature. Furthermore, between the miscibility and disorder-order transition temperature of saturated lipid, the integrated SANS intensity increased slightly, indicating the formation of nano-meter-sized heterogeneity prior to the domain nucleation.     

Oscillatory patterns in a rotating aqueous suspension

Suspensions of granular material in glycerin-water mixtures agitated in horizontally aligned rotating tubes show a whole variety of patterns. The stationary pattern of a homogeneous distribution and a chain of rings have been investigated before. Here we report on two types of oscillatory states in the same system. For a certain range of the rotation frequency and sufficiently high viscosity traveling waves propagate with constant velocity back and forth along the tube in an almost homogeneous distribution of sedimenting particles. The transition from a stationary to the traveling-wave state is found to be an imperfect supercritical bifurcation. The dependence of the wave length and speed on the tube's rotation frequency and the dynamic viscosity of the fluid are determined. Experiments with low viscosities show no traveling waves but low-frequency oscillations, when the previously known chain of rings undergoes a secondary instability.     

Si-based solid blue emitters from 3C-SiC nanocrystals

A procedure for preparing 3C-SiC/SiO₂ composite nanocrystals embedded in Si matrix that emit blue light is reported. Through electrochemical etching of polycrystalline 3C-SiC wafers followed by ultrasonic treatment in water bath, we fabricated luminescent colloidal 3C-SiC nanocrystals. Porous Si samples that have been naturally oxidized in air for 12 h were immersed in agitated aqueous suspension of 3C-SiC nanocrystals for 10 min and then dried in air, followed by annealing in argon atmosphere to form core-shell structured 3C-SiC/SiO₂ nanocrystals embedded in Si matrix. Our result shows that the luminescence of 3C-SiC/SiO₂ composite nanocrystals is very stable over time or under high temperature. As robust and stable Si-based solid blue-emitters, they have important implications for engineering photonic components in optoelectronics and photonics. PACS 78.67.Bf; 78.55.Hx; 78.66.Sq