DISPERSION EFFECTS OF CLUSTER-DERIVED Rh ON SiO_2 OH ETHYLENE HYDROFORMYLATION

Over Rh_4(CO)_(?z)-derived Rh/SiO_2 catalyst,atmospheric hydroformylation and hydro- genation of ethylene are suggested to be structure sensitive and structure insensitive,res- pectively.

A cloud model target damage effectiveness assessment algorithm based on spatio-temporal sequence finite multilayer fragments dispersion

To solve the problem of target damage assessment when fragments attack target under uncertain projectile and target intersection in an air defense intercept,this paper proposes a method for calculating target damage probability leveraging spatio-temporal finite multilayer fragments distribution and the target damage assessment algorithm based on cloud model theory.Drawing on the spatial dispersion characteristics of fragments of projectile proximity explosion,we divide into a finite number of fragments distribution planes based on the time series in space,set up a fragment layer dispersion model grounded in the time series and intersection criterion for determining the effective penetration of each layer of fragments into the target.Building on the precondition that the multilayer fragments of the time series effectively assail the target,we also establish the damage criterion of the perforation and penetration damage and deduce the damage probability calculation model.Taking the damage probability of the fragment layer in the spatio-temporal sequence to the target as the input state variable,we introduce cloud model theory to research the target damage assessment method.Combining the equivalent simulation experiment,the scientific and rational nature of the proposed method were validated through quantitative calculations and comparative analysis.

Unbiased Condition of the Dispersion Effects Estimator in Unreplicated Two-Level Factorial Experiments

This article presents a general form of the estimator for identifying dispersion effects from unreplicated two-level factorial experiments,and shows that the widely used estimators such as the BH,MH,and AMH estimators are all special cases of the proposed one,designated as the G estimator.The unbiased condition of the G estimator is proved,and a lower bound of variance of the G estimator is provided.A simulation based on a realistic design illustrates the variation of the variance and MSE(mean square error) of the G estimator on different coefficients.This estimator may be more flexible and has better performance than other methods such as the BH and MH estimators by appropriately selecting the coefficients.

Effects of Turbulent Dispersion of Atmospheric Balance Motions of Planetary Boundary Layer

New Reynolds' mean momentum equations including both turbulent viscosity and dispersion are used to analyze atmospheric balance motions of the planetary boundary layer. It is pointed out that turbulent dispersion with r 0 will increase depth of Ekman layer, reduce wind velocity in Ekman layer and produce a more satisfactory Ekman spiral lines fit the observed wind hodograph. The wind profile in the surface layer including tur-bulent dispersion is still logarithmic but the von Karman constant k is replaced by k1 = 1 -2/k, the wind increasesa little more rapidly with height.

Effects of Amiodarone on Transmural Dispersion of Ventricular Effective Refractory Periods across Myocardial Layers in the Normal and Hypertrophic Canine Heart

The effects of amiodarone on transmural dispersion of ventricular effective refractory periods （ERPs） in the normal and hypertrophic canine heart were investigated in vivo. By using the programmed stimulation protocol, the ERPs of epicardium （Epi）, midmyocardium （Mid） and endocardium （Endo） were measured by inserting specially-designed electrodes into the three myocardial layers before and after mainlining of amiodarone. No significant ERPs-dispersion was observed in the three layers before and after mainlining of amiodarone in the normal group. In contrast, ERPs of all the three layers were prolonged in the hypertrophic heart, while the ERPs-dispersion was reduced significantly after mainlining of amiodarone. The ERPs-dispersion was significantly increased in the hypertrophic heart but not in the normal heart using ＂long-short＂ and ＂short-long＂ interval stimulation technique. It was concluded that （1） the differences in ERPs-dispersion among the three layers were significant in hypertrophic heart, and differences were not significant in normal canine heart; （2） ERPs of each three-myocardial layers were significantly prolonged after using amioda- rone, but the ERPs-dispersion decreased in hypertrophic heart and （3） the programmed extrastimulus technique of ＂long-short＂ and ＂short-long＂ intervals increased the transmural ERPs-dispersion in the hypertrophic heart.

Viscoacoustic generalized screen propagator in constant-Q model

When seismic waves propagate through the geological formation,there is a significant loss of energy and a decrease in imaging resolution,because of the viscoacoustic properties of subsurface medium.This profoundly impacts seismic wavefield propagation,imaging and interpretation.To accurately image the true structure of subsurface medium,the consensus among geophysicists is to no longer treat subsurface medium as ideal homogeneous medium,but rather to incorporate the viscoacoustic properties of subsurface medium.Based on the generalized screen propagator using conventional acoustic wave equation(acoustic GSP),our developed method introduces viscoacoustic compensation strategy,and derives a one-way wave generalized screen propagator based on time-fractional viscoacoustic wave equation(viscoacoustic GSP).In numerical experiments,we conducted tests on two-dimensional multi-layer model and the Marmousi model.When comparing with the acoustic GSP using the acoustic data,we found that the imaging results of the viscoacoustic GSP using the viscoacoustic data showed a significant attenuation compensation effect,and achieved imaging results for both algorithms were essentially consistent.However,the imaging results of acoustic GSP using viscoacoustic data showed significant attenuation effects,especially for deep subsurface imaging.This indicates that we have proposed an effective method to compensate the attenuated seismic wavefield.Our application on a set of real seismic data demonstrated that the imaging performance of our proposed method in local areas surpassed that of the conventional acoustic GSP.This suggests that our proposed method holds practical value and can more accurately image real subsurface structures while enhancing imaging resolution compared with the conventional acoustic GSP.Finally,with respect to computational efficiency,we gathered statistics on running time to compare our proposed method with conventional Q-RTM,and it is evident that our method exhibits higher computational efficiency.In summary,our proposed viscoacoustic GSP method takes into account the true properties of the medium,still achieves migration results comparable to conventional acoustic GSP.

Effective regulation of the interaction process among three optical solitons

The interaction between three optical solitons is a complex and valuable research direction,which is of practical application for promoting the development of optical communication and all-optical information processing technology.In this paper,we start from the study of the variable-coefficient coupled higher-order nonlinear Schodinger equation(VCHNLSE),and obtain an analytical three-soliton solution of this equation.Based on the obtained solution,the interaction of the three optical solitons is explored when they are incident from different initial velocities and phases.When the higher-order dispersion and nonlinear functions are sinusoidal,hyperbolic secant,and hyperbolic tangent functions,the transmission properties of three optical solitons before and after interactions are discussed.Besides,this paper achieves effective regulation of amplitude and velocity of optical solitons as well as of the local state of interaction process,and interaction-free transmission of the three optical solitons is obtained with a small spacing.The relevant conclusions of the paper are of great significance in promoting the development of high-speed and large-capacity optical communication,optical signal processing,and optical computing.

Dispersion effect on the current voltage characteristic of AlGaN/GaN high electron mobility transistors

The current voltage （IV） characteristics are greatly influenced by the dispersion effects in A1GaN/CaN high electron mobility transistors. The direct current （DC） IV and pulsed IV measurements are performed to give a deep investigation into the dispersion effects, which are mainly related to the trap and self-heating mechanisms. The results show that traps play an important role in the kink effects, and high stress can introduce more traps and defects in the device. With the help of the pulsed IV measurements, the trapping effects and self-heating effects can be separated. The impact of time constants on the dispersion effects is also discussed. In order to achieve an accurate static DC IV measurement, the steady state of the bias points must be considered carefully to avoid the dispersion effects.

Higher-order effects on self-similar parabolic pulse in the microstructured fibre amplifier

By considering higher-order effects, the properties of self-similar parabolic pulses propagating in the microstructured fibre amplifier with a normal group-velocity dispersion have been investigated. The numerical results indicate that the higher-order effects can badly distort self-similar parabolic pulse shape and optical spectrum, and at the same time the peak shift and oscillation appear, while the pulse still reveals highly linear chirp but grows into asymmetry. The influence of different higher-order effects on self-similar parabolic pulse propagation has been analysed. It shows that the self-steepening plays a more important role. We can manipulate the geometrical parameters of the microstructured fibre amplifier to gain a suitable dispersion and nonlinearity coefficient which will keep high-quality self-similar parabolic pulse propagation. These results are significant for the further study of self-similar parabolic pulse propagation.

Pattern Structure of Deterministic Displacement in Random Porous Media with Dispersion Effect

A new model — model of random porous media degradation via several fluid displacing, freezing, and thawing cycles is introduced and investigated in this paper. The fluid transport is based on the deterministic method with dispersion effect. The result shows that the topology and the geometry of the porous media have a strong effect on displacement processes. The cluster size of viscous fingering (VF) pattern in percolation cluster increases with the increase of iteration parameter n. When iteration parameter , VF pattern does not change with n. We find that the displacement fluid forms trapping regions in random porous media with dispersion effect. And the trapping regions will expand with the increasing of the iteration parameter n. When r (throat size) and , the peak value of the distribution increases as n increases, where is the normalized distribution of throat sizes after different displacement-damages but before freezing. The peak value of the distribution reaches a maximum when and , where is the normalized distribution of the size of invaded throat. This result is different from invasion percolation. It is found that the sweep efficiency E increases along with the increasing of iteration parameter n and decreases with the network size L, and E has a minimum as L increases to the maximum size of lattice. The VF pattern in percolation cluster has one frozen zone and one active zone.

Dispersion suppression scheme for Mach-Zehnder interferometer based interleaver using phase shifter

To suppress the dispersion effect, an improved scheme was proposed for Mach-Zehnder intefferometer （MZI） based interleaver. The device consists of an MZI, a fiber loop （FL）, and a phase shifter inserted in FL. The introduction of π phase shifter into FI, dramatically suppresses the dispersion effiect. Then the transmission response remains square-like shape, with low frequency deviation and high extinction ratio. Moreover, the lower frequency deviation is achieved by reducing the dispersion coefficient. For 100GHz-spacing interleaver, the 0.08nm deviation is reduced to 0.02nm by replacing G.652 with G.655.

THE SIZE EFFECT ON THE DISPERSION OF A PARTICLE IN A HOMOGENEOUS ISOTROPIC TURBULENCE

The mechanism of the response motion of a suspended particle to turbulent motion of its surrounding fluid is different according to si:e of turbulent eddies. The particle is dragged by the viscous force of large eddies, and meanwhile driven randomly by small eddies. Based on this understanding, the dispersion of a particle with finite size in a homogeneous isotropic turbulence is calculated in this study. Results show that there are two competing effects: when enhanced by the inertia of a particle, the long-term particle diffusivity is reduced by the finite size of the particle.

Effect of Particle Number Density on Wave Dispersion in a Two-Dimensional Yukawa System

Effect of the particle number density on the dispersion properties of longitudinal and transverse lattice waves in a two-dimensional Yukawa charged-dust system is investigated using molecular dynamics simulation. The dispersion relations for the waves are obtained. It is found that the frequencies of both the longitudinal and transverse dust waves increase with the density and when the density is sufficiently high a cutoff region appears at the short wavelength. With the increase of the particle number density, the common frequency tends to increase, and the sound speed of the longitudinal wave also increases, but that of the transverse wave remains low.

A High-Performance Silicon Electro-Optic Phase Modulator with a Triple MOS Capacitor

We propose and analyze a novel Si-based electro-optic modulator with an improved metal-oxide-semiconductor （MOS） capacitor configuration integrated into silicon-on-insulator （SOl）. Three gate-oxide layers embedded in the silicon waveguide constitute a triple MOS capacitor structure, which boosts the modulation efficiency compared with a single MOS capacitor. The simulation results demonstrate that the Vπ Lπ product is 2. 4V · cm. The rise time and fall time of the proposed device are calculated to be 80 and 40ps from the transient response curve, respectively,indicating a bandwidth of 8GHz. The phase shift efficiency and bandwidth can be enhanced by rib width scaling.

Three kinds of nonlinear dispersive waves in elastic rods with finite deformation

On the basis of classical linear theory on longitudinal, torsional and flexural waves in thin elastic rods, and taking finite deformation and dispersive effects into consideration, three kinds of nonlinear evolution equations are derived. Qualitative analysis of three kinds of nonlinear equations are presented. It is shown that these equations have homoclinic or heteroclinic orbits on the phase plane, corresponding to solitary wave or shock wave solutions, respectively. Based on the principle of homogeneous balance, these equations are solved with the Jacobi elliptic function expansion method. Results show that existence of solitary wave solution and shock wave solution is possible under certain conditions. These conclusions are consistent with qualitative analysis.

Bulbuls and crows provide complementary seed dispersal for China's endangered trees

Background: Different functional frugivores generally exhibit unequal contributions,both in terms of quantity(seed removal) and quality(seedling recruitment),to effective seed dispersal of plant species.However,variations in this dispersal pattern generated by frugivores across different regions are still unknown.Methods: In our study,we evaluated the contributions of two functional frugivore bird groups,the bulbuls(Pycnon?otidae) and crows(Corvidae),in both the seed removal and seedling recruitment of the endangered Chinese yew tree(Taxus chinensis) across three different geographical regions in eastern China.Results: The dominant crow species,Urocissa erythrorhyncha,was the most common disperser crow species at all sites,while the dominant bulbul species varied across the three sites.Furthermore,the two functional groups of dispersers diverged in the aspects of seed removal(quantity) and seedling recruitment pattern(quality).While bulbuls outperformed crows in seed removal(quantity),crows took more seeds to a safer site for seedlings(quality).Conclusions: Our results highlight the importance of variations in the effective seed dispersal patterns of different functional disperser groups across different regions in the conservation and management of endangered tree species.

Multidimensional modal analysis of liquid nonlinear sloshing in right circular cylindrical tank

The multidimensional modal theory proposed by Faltinsen, et al. （2000） is applied to solve liquid nonlinear free sloshing in right circular cylindrical tank for the first time. After selecting the leading modes and fixing the order of magnitudes based on the Narimanov-Moiseev third order asymptotic hypothesis, the general infinite dimensional modal system is reduced to a five dimensional asymptotic modal system （the system of second order nonlinear ordinary differential equations coupling the generalized time dependent coordinates of free surface wave elevation）. The numerical integrations of this modal system discover most important nonlinear phenomena, which agree well with both pervious analytic theories and experimental observations. The results indicate that the multidimensional modal method is a very good tool for solving liquid nonlinear sloshing dynamics and will be developed to investigate more complex sloshing problem in our following work.

High-speed 2 × 2 silicon-based electro-optic switch with nanosecond switch time

A 2 × 2 electro-optic switch is experimentally demonstrated using the optical structure of a Mach-Zehnder interferometer （MZI） based on a submicron rib waveguide and the electrical structure of a PIN diode on silicon-on-insulator （SOI）. The switch behaviour is achieved through the plasma dispersion effect of silicon. The device has a modulation arm of 1 mm in length and cross-section of 400 nm×340 nm. The measurement results show that the switch has a VπLπ figure of merit of 0.145 V.cm and the extinction ratios of two output ports and cross talk are 40 dB, 28 dB and -28 dB, respectively. A 3 dB modulation bandwidth of 90 MHz and a switch time of 6.8 ns for the rise edge and 2.7 ns for the fall edge are also demonstrated.

Improved power simulation of AlGaN/GaN HEMT at class-AB operation via an RF drain–source current correction method

A new modified Angelov current–voltage characteristic model equation is proposed to improve the drain–source current（Ids） simulation of an Al Ga N/Ga N-based（gallium nitride） high electron mobility transistor（Al Ga N/Ga N-based HEMT） at high power operation. Since an accurate radio frequency（RF） current simulation is critical for a correct power simulation of the device, in this paper we propose a method of Al Ga N/Ga N high electron mobility transistor（HEMT）nonlinear large-signal model extraction with a supplemental modeling of RF drain–source current as a function of RF input power. The improved results of simulated output power, gain, and power added efficiency（PAE） at class-AB quiescent bias of Vgs =-3.5 V, Vds= 30 V with a frequency of 9.6 GHz are presented.

Heavy Atom Effect on the First Hyperpolarizabilities of Squaric Acid Homologues Studied by Ab Initio and DFT Methods

We have calculated the first hyperpolarizabilities of four squaric acid homologue molecules: 3,4-dithiohydroxy-3-cyclobutene-1,2-dione (OSSQ), 3,4-dithiohydroxy-3-cyclobutene-1, 2-dithione (SSSQ), 3,4-dithiohydroxy-3-cyclobutene-1,2-diselenone (SeSSQ) and 3,4-dithiohydroxy- 3-cyclobutene-1,2-ditellurone (TeSSQ). The correlation effect was investigated at the second-order Mller-Plesset (MP2) perturbation and density functional theory (DFT) levels. The frequency disper- sion and solvent effect were considered to compare the theoretical values with the experimental observations. Based on all of these studies, it is worthy to point out that the heavy atom effect dis- covered for furan homologues is an influence on the first hyperpolarizabilities of squaric acid homologues.