Simulation of the Equatorially Asymmetric Mode of the Hadley Circulation in CMIP5 Models

The tropical Hadley circulation （HC） plays an important role in influencing the climate in the tropics and extra-tropics. The realism of the climatological characteristics, spatial structure, and temporal evolution of the long-term variation of the principal mode of the annual mean HC （i.e., the equatorially asymmetric mode, EAM） was examined in model simulations from the Coupled Model Intercomparison Project Phase 5 （CMIP5）. The results showed that all the models are moderately successful in capturing the HC＇s climatological features, including the spatial pattern, meridional extent, and intensity, but not the spatial or temporal variation of the EAM. The possible reasons for the poor simulation of the long-term variability of the EAM were explored. None of the models can successfully capture the differences in the warming rate between the tropical Southern Hemisphere （SH） and Northern Hemisphere （NH）, which is considered to be an important driver for the variation of the AM. Most of the models produce a faster warming in the NH than in the SH, which is the reverse of the observed trend. This leads to a reversed trend in the meridional gradient between the SH and NH, and contributes to the poor simulation of EAM variability. Thus, this aspect of the models should be improved to provide better simulations of the variability of the HC. This study suggests a possible reason for the poor simulation of the HC, which may be helpful for improving the skill of the CMIP5 models in the future.

Dynamic propagation problems concerning surfaces of asymmetrical mode III crack subjected to moving loads

With the theory of complex functions, dynamic propagation problems concerning surfaces of asymmetrical mode Ⅲ crack subjected to moving loads are investigated. General representations of analytical solutions are obtained with self-similar functions. The problems can be easily converted into Riemann-Hilbert problems using this technique. Analytical solutions to stress, displacement and dynamic stress intensity factor under constant and unit-step moving loads on the surfaces of asymmetrical extension crack, respectively, are obtained. By applying these solutions, together with the superposition principle, solutions of discretionarily intricate problems can be found.

Ultra-broadband asymmetric acoustic transmission with single transmitted beam

We report both experimentally and numerically that ultra-broadband asymmetric acoustic transmission is realized by a brass plate and a right triangle reflector immersed in water. This exotic phenomenon arises from the asymmetric excitation of the leaky asymmetric zero-order Lamb mode in the brass plate induced by the incident angle of external bulk waves. The results show that the bandwidth of the asymmetric acoustic transmission could reach 2000 k Hz, and the positive transmitted wave is only a single acoustic beam. The device has the advantages of ultra-broadband, single transmitted beam,and simpler structure, which has great potential applications in ultrasonic devices.

Bridging the Fabry–Perot cavity and asymmetric Berreman mode for long-wave infrared nonreciprocal thermal emitters

The long-wave infrared band(8–14μm)is essential for several applications,such as infrared detection,radiative cooling,and near-field heat transfer.However,according to Kirchhoff’s law,the intrinsic balance between thermal absorption and emission limits the further improvement of photon energy conversion and thermal management.Thus,breaking Kirchhoff’s balance and achieving nonreciprocal thermal radiation in the long-wave infrared band are necessary.Most existing designs for nonreciprocal thermal emitters rely on grating or photonic crystal structures to achieve nonreciprocal thermal radiation at narrow peaks,which are relatively complex and typically realize bands larger than 14μm.Here,a sandwich structure consisting of an epsilon-nearzero(ENZ)magneto-optical layer(MOL),a dielectric layer(DL),and a metal layer is proposed to achieve a strong nonreciprocal effect in the long-wave infrared band,which is mainly attributed to the strengthening of the asymmetric Berreman mode by the Fabry–Perot cavity.In addition,the impact of the incident angle,DL thickness,and DL refractive index on the nonreciprocal thermal radiation has been investigated.Moreover,by replacing the ENZ MOL with the gradient ENZ MOL,the existence of the DL can further improve the nonreciprocity of the broadband nonreciprocal thermal radiation.The proposed work promotes the development and application of nonreciprocal energy devices.

Natural dynamic characteristics of a circular cylindrical Timoshenko tube made of three-directional functionally graded material

The natural dynamic characteristics of a circular cylindrical tube made of three-directional(3 D)functional graded material(FGM)based on the Timoshenko beam theory are investigated.Hamilton’s principle is utilized to derive the novel motion equations of the tube,considering the interactions among the longitudinal,transverse,and rotation deformations.By dint of the differential quadrature method(DQM),the governing equations are discretized to conduct the analysis of natural dynamic characteristics.The Ritz method,in conjunction with the finite element method(FEM),is introduced to verify the present results.It is found that the asymmetric modes in the tube are controlled by the 3 D FGM,which exhibit more complicated shapes compared with the unidirectional(1 D)and bi-directional(2 D)FGM cases.Numerical examples illustrate the effects of the axial,radial,and circumferential FGM indexes as well as the supported edges on the natural dynamic characteristics in detail.It is notable that the obtained results are beneficial for accurate design of smart structures composed from multi-directional FGM.

Chiral asymmetry of anti-symmetric coordinates studied by the Raman differential bond polarizability of S-phenylethylamine

The Raman optical activity （ROA） study on S-phenylethylamine is presented by the intensity analyses via bond polarizability and differential bond polarizability. Ample information concerning the physical picture of this chiral system is obtained, and its ROA mechanism is constructed. Especially, we propose that the asymmetric modes and/or the off-diagonal elements of the electronic polarizability tensor are the potential keys to the exploration of ROA.

Precipitation Distribution of the Extended Global Spring-Autumn Monsoon and Its Possible Formation Mechanism

The global monsoon(GM)comprises two major modes,namely,the solstitial mode and equinoctial asymmetric mode.In this paper,we extend the GM domain from the tropics to the global region and name it the global spring-autumn monsoon(GSAM),which mainly indicates a spring-autumn asymmetrical precipitation pattern exhibiting annual variation.Its distribution and possible formation mechanisms are also analyzed.The GSAM domain is mainly distributed over oceans,located both in the midlatitude and tropical regions of the Pacific and Atlantic.In the GSAM domains of both the Northern and Southern Hemispheres,more precipitation occurs in local autumn than in local spring.The formation mechanisms of GSAM precipitation vary according to the different domains.GSAM precipitation in the tropical domain of the Eastern Hemisphere is influenced by the circulation differences between the onset and retreat periods of the Asian summer monsoon,while tropical cyclone activities cause precipitation over the South China Sea(SCS)and western North Pacific(WNP).GSAM precipitation in the tropical domain of the Western Hemisphere is influenced by the tropical asymmetrical circulation between the Northern and Southern Hemispheres and the variation in the intertropical convergence zone(ITCZ)driven by the intensity of the sea surface temperature cold tongues over the equatorial eastern Pacific and eastern Atlantic.GSAM precipitation in the midlatitude domain is influenced by the differences in water vapor transportation and convergence between spring and autumn.In addition,GSAM precipitation is also affected by extratropical cyclone activities.

Gap induced mode evolution under the asymmetric structure in a plasmonic resonator system

The modulation of resonance features in microcavities is important to applications in nanophotonics.Based on the asymmetric whispering-gallery modes(WGMs)in a plasmonic resonator,we theoretically studied the mode evolution in an asymmetric WGM plasmonic system.Exploiting the gap or nano-scatter in the plasmonic ring cavity,the symmetry of the system will be broken and the standing wave in the cavity will be tunable.Based on this asymmetric structure,the output coupling rate between the two cavity modes can also be tuned.Moreover,the proposed method could further be applied for sensing and detecting the position of defects in a WGM system.

Deformation parameter changes in fission mass yields within the systematic statistical scission-point model

The fission fragment mass-yields are evaluated for pre-actinide and actinide isotopes using a systematic statistical scission point model.The total potential energy of the fissioning systems at the scission point is presented in approximate relations as functions of mass numbers,deformation parameters and the temperature of complementary fission fragments.The collective temperature,Tcoll,and the temperature of fission fragments,Ti,are separated and the effect of collective temperature on mass yields results is investigated.The fragment temperature has been calculated with the generalized superfluid model.The sum of deformation parameters of complementary fission fragments has been obtained by fitting the calculated results with the experimental data.To investigate the transitions between symmetric and asymmetric modes mass yields for pre-actinide and heavy actinides are calculated with this model.The transition from asymmetric to symmetric fission is well reproduced using this systematic statistical scission point model.The calculated results are in good agreement with the experimental data with Tcoll=2 Me V at intermediate excitation energy and with T_(coll)=1MeV for spontaneous fission.Despite the Langevin model,in the scission point model,a constraint on the deformation parameters of fission fragments has little effect on the results of the mass yield.