Strip Waveguide Directional Coupling Modulator with Equivalent Refractive Index

The equivalent refractive index（ERI） method is employed to analyze the function of the strip waveguide directional coupling modulator（SWM）. Through deducing the diagnostic equation of the Exmn mode of the four-layer media film waveguide equivalent to the SWM,the transmission constant of the symmetrical mode of the positive phase and negative one and the coupling length of powerful transference are obtained. The veracity of ERI is validated with the example of Ex11 basal mode under conditions of comparing the three results of ERI,EIM and Marcatili.

THEORETICAL MODEL OF EFFECTIVE STRESS COEFFICIENT FOR ROCK/SOIL-LIKE POROUS MATERIALS

Physical mechanisms and influencing factors on the effective stress coefficient for rock/soil-like porous materials are investigated, based on which equivalent connectivity index is proposed. The equivalent connectivity index, relying on the meso-scale structure of porous material and the property of liquid, denotes the connectivity of pores in Representative Element Area （REA）. If the conductivity of the porous material is anisotropic, the equivalent connectivity index is a second order tensor. Based on the basic theories of continuous mechanics and tensor analysis, relationship between area porosity and volumetric porosity of porous materials is deduced. Then a generalized expression, describing the relation between effective stress coefficient tensor and equivalent connectivity tensor of pores, is proposed, and the expression can be applied to isotropic media and also to anisotropic materials. Furthermore, evolution of porosity and equivalent connectivity index of the pore are studied in the strain space, and the method to determine the corresponding functions in expressions above is proposed using genetic algorithm and genetic programming. Two applications show that the results obtained by the method in this paper perfectly agree with the test data. This paper provides an important theoretical support to the coupled hydro-mechanical research.

Apodized grating coupler using fully-etched nanostructures

A two-dimensional apodized grating coupler for interfacing between single-mode fiber and photonic circuit is demonstrated in order to bridge the mode gap between the grating coupler and optical fiber. The grating grooves of the grating couplers are realized by columns of fully etched nanostructures, which are utilized to digitally tailor the effective refractive index of each groove in order to obtain the Gaussian-like output diffractive mode and then enhance the coupling efficiency.Compared with that of the uniform grating coupler, the coupling efficiency of the apodized grating coupler is increased by 4.3% and 5.7%, respectively, for the nanoholes and nanorectangles as refractive index tunes layer.

Adult size and tinning of reproduction in five species of Asobara parasitoid wasps

The majority o f adult parasitoid wasps are unable to synthesize lipids and therefore face a trade-off between the investment of lipids in eggs or in the maintenance of soma.It has been shown that resource allocation should depend on body size in parasitoids.Given that smaller females have shorter expected life times,they should concentrate their reproductive effort into early life.To test this prediction,we investigated the relationship between body size and the timing of egg production in parasitoids.We measured body size,lipid reserves,and reproductive investment(number of eggs,ovigeny index equivalent[OIE]and egg size)at eclosion in five species of Asobara(Hymenoptera:Braconidae)originating from different geographic and climatic environments.Our results show significant interspecific variation in all these traits.A diagnostic test for phylogenetic independence revealed that closely related species did not resemble each other more closely than expected by chance for all traits measured.Lipid reserves scaled positively with body size both between and within species.In agreement with theory,01 correlated negatively with body size both between and within species.Total egg area at eclosion correlated negatively with lipid reserves both between and within species.This indicates the existence of a trade-off between allocation of lipids to current reproduction and survival/future reproduction.With the exception of the most extreme pro-ovigenic species,A.pers im ilis,we found that proovigeny was compensated for by small egg size.Our results indicate the role of habitats in shaping interspecific variation in resource allocation strategies.