Asian Summer Monsoon Onset in Simulations and CMIP5 Projections Using Four Chinese Climate Models

The reproducibility and future changes of the onset of the Asian summer monsoon were analyzed based on the simulations and projections under the Representative Concentration Pathways （RCP） scenario in which anthropogenic emissions continue to rise throughout the 21 st century （i.e. RCP8.5） by all realizations from four Chinese models that participated in the Coupled Model Intercomparison Project Phase 5 （CMIP5）. Delayed onset of the monsoon over the Arabian Sea was evident in all simulations for present-day climate, which was associated with a too weak simulation of the low-level Somali jet in May. A consistent advanced onset of the monsoon was found only over the Arabian Sea in the projections, where the advanced onset of the monsoon was accompanied by an increase of rainfall and an anomalous anticyclone over the northern Indian Ocean. In all the models except FGOALS-g2, the enhanced low-level Somali jet transported more water vapor to the Arabian Sea, whereas in FGOALS-g2 the enhanced rainfall was determined more by the increased wind convergence. Furthermore, and again in all models except FGOALS-g2, the equatorial SST warming, with maximum increase over the eastern Pacific, enhanced convection in the central West Pacific and reduced convection over the eastern Indian Ocean and Maritime Continent region, which drove the anomalous anticyclonic circulation over the western Indian Ocean. In contrast, in FGOALS-g2, there was minimal （near-zero） warming of projected SST in the central equatorial Pacific, with decreased convection in the central West Pacific and enhanced convection over the Maritime Continent. The broader-scale differences among the models across the Pacific were related to both the differences in the projected SST pattern and in the present-day simulations.

A preliminary investigation on the topology of Chinese climate networks

Complex networks have been studied across many fields of science in recent years. In this paper, we give a brief introduction of networks, then follow the original works by Tsonis et al （2004, 2006） starting with data of the surface temperature from 160 Chinese weather observations to investigate the topology of Chinese climate networks. Results show that the Chinese climate network exhibits a characteristic of regular, almost fully connected networks, which means that most nodes in this case have the same number of links, and so-called super nodes with a very large number of links do not exist there. In other words, though former results show that nodes in the extratropical region provide a property of scale-free networks, they still have other different local fine structures inside. We also detect the community of the Chinese climate network by using a Bayesian technique; the effective number of communities of the Chinese climate network is about four in this network. More importantly, this technique approaches results in divisions which have connections with physics and dynamics; the division into communities may highlight the aspects of the dynamics of climate variability.

The El Ni?o-Southern Oscillation cycle simulated by the climate system model of Chinese Academy of Sciences

On the basis of more than 200-year control run, the performance of the climate system model of Chinese Academy of Sciences （CAS-ESM-C） in simulating the E1 Nifio-Southern Oscillation （ENSO） cycle is evalu- ated, including the onset, development and decay of the ENSO. It is shown that, the model can reasonably simulate the annual cycle and interannual variability of sea surface temperature （SST） in the tropical Pacif- ic, as well as the seasonal phase-locking of the ENSO. The model also captures two prerequisites for the E1 Nino onset, i.e., a westerly anomaly and a warm SST anomaly in the equatorial western Pacific. Owing to too strong forcing from an extratropical meridional wind, however, the westerly anomaly in this region is largely overestimated. Moreover, the simulated thermocline is much shallower with a weaker slope. As a result, the warm SST anomaly from the western Pacific propagates eastward more quickly, leading to a faster develop- ment of an E1 Nino. During the decay stage, owing to a stronger E1Nino in the model, the secondary Gill-type response of the tropical atmosphere to the eastern Pacific warming is much stronger, thereby resulting in a persistent easterly anomaly in the western Pacific. Meanwhile, a cold anomaly in the warm pool appears as a result of a lifted thermocline via Ekman pumping. Finally, an E1 Nino decays into a La Nina through their interactions. In addition, the shorter period and larger amplitude of the ENSO in the model can be attribut- ed to a shallower thermocline in the equatorial Pacific, which speeds up the zonal redistribution of a heat content in the upper ocean.

Spatial variability of glacial changes and their effects on water resources in the Chinese Tianshan Mountains during the last five decades

Changes in glaciers in the Chinese Tianshan Mountains have been analyzed previously. However, most previous studies focused on individual glaciers and/or decentralized glacial basins. Moreover, a majority of these studies were published only in Chinese, which limited their usefulness at the international level. With this in mind, the authors reviewed the previous studies to create an overview of glacial changes in the Chinese Tianshan Mountains over the last five decades and discussed the effects of glacial changes on water resources. In response to climate change, glaciers in the Tianshan Mountains are shrinking rapidly and are ca. 20% smaller on average in the past five decades. Overall, the area reduction of glacial basins in the central part of the Chinese Tianshan Mountains is larger than that in the eastern and western parts. The spatial differentiation in glacial changes are caused by both differences in regional climate and in glacial factors. The effects of glacial changes on water resources vary in different river basins due to the differences in glacier distribution, characteristics of glacial change and proportion of the glacier meltwater in river runoff.

A Thermodynamic Cavitation Model for Cavitating Flow Simulation in a Wide Range of Water Temperatures

A thermodynamic cavitation model is developed to simulate the cavitating water flow in a wide temperature range. The thermal effect on bubble growth during cavitation is introduced in the developed model by considering both pressure difference and heat transfer between the vapor and liquid phase. The cavitating turbulent flow over a NACA0015 hydrofoil has been simulated at various temperatures from room temperature to 150°C by using the present cavitation model, which has been validated by the experimental data. It is seen that the thermodynamic effects of cavitation, vapor depression and temperature depression are much more predominant in high temperature water compared with those in room temperature water. These results indicate that the proposed thermodynamic cavitation model is reasonably applicable to the cavitating water flow in a wide temperature range.

Vibration Characteristics of Acoustically Levitated Object with Rigid and Elastic Reflectors

Levitation stability is a crucial factor that influences acoustic levitation capability. We present two sample-including models for a single-axis acoustic levitator with either a rigid or elastic reflector. Numerical analysis shows that, with the rigid reflector, both the decay time from initial disturbance and the vibration amplitude increase with sample density, which is unfavorable for levitation stability. However, with the elastic reflector, the decay time and the vibration amplitude are greatly reduced by choosing appropriate parameters of the reflector. Experimental results agree well with theoretical predictions, indicating that levitation stability can be remarkably enhanced by replacing the rigid reflector with an elastic reflector.

Optical Switch Formation in Antimony Super-Resolution Mask Layers Induced by Picosecond Laser Pulses

Sb is a classic material of a super-resolution near field structure （super-RENS） mask layer in which the optical switch formation is often realized by nanosecond laser pulse stimulation. We achieve fast and repeatable optical switching driven by picosecond laser pulses in a proper fluence range on Sb thin films. The optical properties of Sb thin films before and after switching are studied by surface-sensitive micro-area ellipsometry. The change of optical constants after switching is less than 2% in the whole visible range. The Sb mask layer is shown to be very promising for ultrafast super-resolution optical storage applications.

Evaluation of Thermal Degradation Induced Material Damage Using Nonlinear Lamb Waves

We report on the evaluation of thermal degradation damage in metal material using the nonlinear effect of Lamb wave propagation. A mountain-shape＇＇ change in the second harmonic of Lamb wave propagation versus the level of thermal degradation in the specimens is observed. It is attributed to the precipitations in the early stage and the microvoids after long-term service in terms of metallographic studies. The results show that the nonlinear Lamb wave is very sensitive to the microstructure evolution and is a good potential for quantitative evaluation of the thermal damaged materials.

Measurement of Refractive Index for High Reflectance Materials with Terahertz Time Domain Reflection Spectroscopy

A method to measure the refractive index for high reflectance materials in the terahertz range with terahertz time domain reflection spectroscopy is proposed. In this method, the THz waveforms reflected by a silicon wafer and high reflectance sample are measured respectively. The refractive index of the silicon wafer, measured with the THz time domain transmission spectroscopy, is used as a reference in the THz time domain reflective spectroscopy. Therefore, the complex refractive index of the sample can be obtained by resorting to the known reflective index of the silicon and the Fresnel law. To improve the accuracy of the phase shift, the Kramers-Kronig transform is adopted. This method is also verified by the index of the silicon in THz reflection spectroscopy. The bulk metal plates have been taken as the sample, and the experimentally obtained metallic refractive indexes are compared with the simple Drude model.

Evolution of Ring Current Protons Induced by Electromagnetic Ion Cyclotron Waves

We investigate the evolution of the phase space density （PSD） of ring current protons induced by electromagnetic ion cyclotron （EMIC） waves at the location L=3.5, calculate the diffusion coefficients in pitch angle and momentum, and solve the standard two-dimensional Fokker-Planck diffusion equation. The pitch angle diffusion coefficient is found to be larger than the momentum diffusion coefficient by a factor of about 103 or above at lower pitch angles. We show that EMIC waves can produce efficient pitch angle scattering of energetic （- 100 keV） protons, yielding a rapid decrement in PSD, typically by a factor of - 10 within a few hours, consistent with observational data. This result further supports previous findings that wave-particle interaction is responsible for the rapid ring current decay.

An SPICE Model for PCM Based on Arrhenius Equation

Based on the temperature dependence of the Arrhenius law, an HSPICE compact module using Verilog-A language for phase change memory （PCM） is presented. In the model of this HSPICE compact module, the basic theory that the resistance of the amorphous semiconductor has relations with the activation energy and temperature is used, and an assumption that this theory can be expanded to describe the crystalline semiconductor is employed. Moreover, since an objective reality that the resistance of the semiconductor determines the temperature and the temperature affects the resistance inversely is inevitable, coupling with such positive feedback, this model can reproduce the real-time characteristics of the memory cell accurately. The simulation results show that this model can reproduce the features of the PCM cell well. It can be used in the PCM circuit design and further analysis.

A Kind of Double-Cladding Photonic Crystal Fiber with High Birefringence and Two Zero-Dispersion Wavelengths

A kind of double-cladding photonic crystal fiber （DC-PCF） with high birefringence and two zero-dispersion wavelengths is proposed. It is found that the birefringence of DC-PCF with inner cladding air holes pitch 1.0μm and diameter 0.8μm is 1.001×10-2 in the optical communication band at wavelength 1.55μm by the multipole method. It is demonstrated that two zero dispersion wavelengths can be achieved in the optical communication band between 0.8μm and 1.7μm, and the first zero-dispersion wavelength is in the working wave band of the Ti：sapphire oscillator, which contributes to the frequency conversion of the Ti：sapphire femtosecond laser. PCF with two zero-dispersion wavelengths can make strong power supercontinuum spectral in the near infrared band.

Linear Analysis of Folded Double-Ridged Waveguide Slow-Wave Structure for Millimeter Wave Traveling Wave Tube

A novel slow-wave structure （SWS）, the folded double-ridged waveguide structure, is presented and its linear gain properties are investigated. The perturbed dispersion equation is derived and the small signal growth rate is caleulated for dimensions of the ridge-loaded region and the parameters of the electron beam. The novel structure has potential applications in the production of high power and broad band radiation. For a cold beam, the linear theory predicts a gain of 1.1-1.27dB/period and a 3-dB small-signal gain bandwidth of 30% in W-band. A comparison between the folded double-ridged waveguide SWS and folded waveguide SWS （FWSWS） shows that with the same physical parameters, the novel SWS has an advantage over the FWSWS on the bandwidth and electron efficiency.

Period Continuous Tuning of an Efficient Mid-Infrared Optical Parametric Oscillator Based on a Fan-out Periodically Poled MgO-Doped Lithium Niobate

We report a period continuously tunable, efficient, mid-infrared optical parametric oscillator （OPO） based on a fan-out periodically poled MgO-doped congruent lithium niobate （PPMgLN）. The OPO is pumped by a Nd：YAG laser and a maximum idler output average power of 1.65W at 3.93μm is obtained with a pump average power of 10.5W, corresponding to the conversion efficiency of about 16% from the pump to the idler. The output spectral properties of the OPO with the fan-out crystal are analyzed. The OPO is continuously tuned over 3.78-4.58μm （idler） when fan-out periods are changed from 27.0 to 29.4μm. Compared with temperature tuning, fan-out period continuous tuning has faster tuning rate and wider tuning range.

Coupling of Acoustical Plane p-Wave to a Cased Borehole

Theoretical and numerical study on the coupling acoustic field of the plane p-wave to a cased borehole is carried out. The medium outside the cased borehole is modeled as the porous medium. The scattering field characteristics in the cased borehole are investigated when a plane fast p-wave is incident in tilt to the cased borehole from the porous medium. The scattering fields inside and outside the cased borehole are analyzed and deduced by Biot＇s theory under the boundary conditions on each interface, and they are numerically studied. It is found that the scattering field has strong resonant characteristics and there exists a series of resonant frequencies and peaks. The effects of the frequency, radii of each interface, incident angle, porosity, and other parameters on the resonant acoustic field have been investigated in detail in the fast and slow formations respectively. The resonant characteristics of the scattering field are also analyzed from the physical sense.

Highly Symmetric Planar Metamaterial Absorbers Based on Annular and Circular Patches

We present the simple designs of metamaterial absorbers which are composed of a periodic array of copper annular （or circular） patches, FR4 substrate, and copper film. With appropriate geometrical parameters, these metamaterials can provide the electric and magnetic resonances overlapping in the given frequency range, and the experiments demonstrate the absorptivities of 97.6% and 96.7% with only a single layer of the metamaterial absorber. The surface currents and field distributions of these metamaterials are discussed to look straight into the resonance mechanism. Furthermore, our numerical simulations confirm that these metamaterial absorbers could be operated at wide angles of incidence. The simple and highly symmetric structures of the metamaterial absorbers proposed would greatly accelerate the practical applications in optics and electromagnetics.

Equation of State of Tantalum up to 133GPa

The static equation of state （EOS） of tantalum （Ta） is determined by in situ energy-dispersive synchrotron powder x-ray diffraction in a diamond anvil cell （DAC） up to 133GPa. The body-centered-cubic （bcc） phase of Ta is found to be stable over the entire pressure range investigated. The bulk moduli and its first pressure derivative of Ta are constrained by fitting the determined pressure-volume data to Vinet form EOS： B0 =192.65±（3.08）GPa and B＇0 =3.58±（0.11）. For the sake of avoiding the affect of non-hydrostatic stress, argon is used as a pressure media. A careful checking of the stress state of the sample is presented simultaneously.

Cap Layer Influence on Impurity-Free Vacancy Disordering of InGaAs/InP Quantum Well Structure

Quantum well intermixing （QWI） by the impurity-free vacancy disordering （IFVD） technique is an important and effective approach for the monolithic integration of optoelectronic devices based on InGaAs/InP quantum well structures. We experimentally investigate the influence of the capping layer SiO2 and Si3N4 on the QWI by IFVD. The results show that for all the samples with three-types differently doped （P, N and I） top InP layers, Si3N4 can always induce a larger photoluminescence blueshift than SiO2 in the IFVD QWI process, which attributes more to the group III and V vacancies point defects created in the interface of Si3N4-InP than that of SiO2-InP, proved by the SIMS measurements. The inherent mechanisms for explaining these properties are further discussed.

Design of a High-Nonlinearity Single-Mode Holey Fiber with Flattened Dispersion around 800 nm

We numerically demonstrate a high-nonlinearity single-mode holey fiber with flattened dispersion around the Ti-Za laser band at 800 nm. The dispersion profile of the fiber has the shape of a quadratic curve, which reaches its maximum 5.96 ps·km^-1·nm^-1 at 800hm and its minimum -0.897 ps·km^-1·nm^-1 at both 750 and 850 nm. The nonlinear coefficient is 170 W^-1 km^-1 at 800nm and no higher order modes exit. A six-layer air-hole cladding ensures a loss less than 0.067 db/m in the 750 to 850 nm range. Two more air-hole rings will reduce the loss to below 0.1 db/km.

Characterizations of Stress and Strain Variation in Three-Dimensional Forming of Laser Micro-Manufacturing

A micro-manufacturing technology is presented to form three-dimensional metallic micro-structures directly. Micro grid array structures are replicated on a metallic foil surface, with high spatial resolution in micron levels. The numerical simulation results indicate that the material deformation process is characterized by an ultrahigh strain rate. With increasing pulse duration, the sample absorption strain energy increases, and the sample deformation degree enlarges. The stress state of the central point fluctuates between tensile stress and compression stress. The stress state of the angular point is altered from compressive stress to tensile stress due to geometry and loading conditions. The duration length of pulse stress has an effect on the stress state, as with the increase of pulse duration, fluctuation in the stress state decreases. Therefore, laser micro-manufacturing technology will be a potential laser micro forming method which is characterized by low cost and high efficiency.