Solitons and intrinsic localized modes in a one-dimensional antiferromagnetic chain

By use of the Hartree approximation and the method of multiple scales, we investigate quantum solitons and intrinsic localized modes in a one-dimensional antiferromagnetic chain. It is shown that there exist solitons of two different quantum frequency bands： i.e., magnetic optical solitons and acoustic solitons. At the boundary of the Brillouin zone, these solitons becornc quantum intrinsic localized modes： their quantum eigenfrequencics are below the bottom of the harmonic optical frequency band and above the top of the harmonic acoustic frequency band.

Quantum Solitons and Localized Modes in a One-Dimensional Lattice Chain with Nonlinear Substrate Potential

In the classical lattice theory, solitons and localized modes can exist in many one-dimensional nonlinear lattice chains, however, in the quantum lattice theory, whether quantum solitons and localized modes can exist or not in the one-dimensional lattice chains is an interesting problem. By using the number state method and the Hartree approximation combined with the method of multiple scales, we investigate quantum solirons and localized modes in a one-dimensional lattice chain with the nonlinear substrate potential. It is shown that quantum solitons do exist in this nonlinear lattice chain, and at the boundary of the phonon Brillouin zone, quantum solitons become quantum localized modes, phonons are pinned to the lattice of the vicinity at the central position j = j0.

Bright and dark small amplitude nonlinear localized modes in a quantum one-dimensional Klein-Gordon chain

By means of the Glauber＇s coherent state method combined with multiple-scale method, this paper investigates the localized modes in a quantum one-dimensional Klein-Gordon chain and finds that the equation of motion of annihilation operator is reduced to the nonlinear Schroedinger equation. Interestingly, the model can support both bright and dark small amplitude travelling and non-travelling nonlinear localized modes in different parameter spaces.

Intrinsic Localized Modes in an Order-parameter-preserving Antiferromagnet

Intrinsic localized modes in an order-parameter-preserving antiferromagnet are investigated with employing the Dyson-Maleev transformation and the coherent-state ansatz. These modes which be- low the magnon frequency band correspond to a local large-angle, low-frequency precessional mo- tion of spins, quantum states of which are characterized by the indefiniteness of the number of rele- vant magnons.

Estimation of tungsten production from the upper divertor in EAST during edge localized modes

During edge localized modes(ELMs), the sheath evolution in front of the Experimental Advanced Superconducting Tokamak(EAST) upper divertor is studied to estimate the sputtered tungsten(W) atoms from the divertor target. A large potential drop across the sheath is formed during ELMs by compared with inter-ELMs, and the maximum of sheath potential drop can exceed one thousand of e V in current EAST operation. Due to the enhancement of the sheath potential drop during ELMs, the W physical sputtering yield from the deuterium(D) ions and the impurity ions on the upper divertor target is found to be significant. It is established that the sputtered W yield during ELMs is at least higher by an order of magnitude than inter-ELMs, and D ions and carbon(C) ions are the main ions governing the W production for the current H-mode with ELMs discharges. With increase in the pedestal electron temperature, the maximum of the D and C ion impact energy during ELMs shows a nearly linear increase, and the D ions have sufficient impact energy to cause the strong W physical sputtering. As a consequence, the D ions may dominate the sputtered W flux from the divertor target when the C concentration is controlled less than one percent for the higher heating power H-mode with ELM discharges in near future.

Edge localized modes suppression via edge E × B velocity shear induced by RF sheath of ion cyclotron resonance heating in EAST

The control of large edge localized modes(ELMs) is a critical issue for the successful operation of future burning plasma devices,such as the international thermonuclear experimental reactor(ITER) and China fusion engineering test reactor(CFETR). In this paper, we present a new active and effective means of ELM suppression using ion cyclotron resonant heating(ICRH) on the experimental advanced superconducting tokamak(EAST). We obtained the key role of the external E × B velocity shear near the pedestal top and the scrape-off-layer(SOL) induced by the RF sheath potential of ICRH in ELM suppression. The experimental results showed a positive correlation between the RF sheath and the E × B shear rate in SOL. BOUT++ simulations indicate that increased E × B velocity shear rates in the pedestal and SOL regions promote ELM suppression;thereby, supporting the experimental observations on EAST. These findings suggest a new simple approach to access the ELM suppressed regimes in plasma with low torque input as ITER baseline discharges.

Investigation of lower hybrid current drive during H-mode in EAST tokamak

H-mode discharges with lower hybrid current drive （LHCD） alone are achieved in EAST divertor plasma over a wide parameter range. These H-mode discharges are characterized by a sudden drop in Da emission and a spontaneous rise in main plasma density. Good lower hybrid （LH） coupling during H-mode is obtained by putting the plasma close to the antenna and by injecting D2 gas from a pipe near the grill mouse. The analysis of lower hybrid current drive properties shows that the LH deposition profile shifts off axis during H-mode, and current drive （CD） efficiency decreases due to the increase in density. Modeling results of H-mode discharges with a general ray trueing code GENRAY are reported.

Research on mode localization of reticulated shell structures

Reticulated shell structures （RSSs） are characterized as cyclically periodic structures. Mistuning of RSSs will induce structural mode localization. Mode localization has the following two features： some modal vectors of the structure change remarkably when the values of its physical parameters （mass or stiffness） have a slight change; and the vibration of some modes is mainly restricted in some local areas of the structure. In this paper, two quantitative assessment indexes are introduced that correspond to these two features. The first feature is studied through a numerical example of a RSS, and its induced causes are analyzed by using the perturbation theory. The analysis showed that internally, mode localization is closely related to structural frequencies and externally, slight changes of the physical parameters of the structure cause instability to the RSS. A scaled model experiment to examine mode localization was carried out on a Kiewit single-layer spherical RSS, and both features of mode localization are studied. Eight tests that measured the changes of the physical parameters were carried out in the experiment. Since many modes make their contribution in structural dynamic response, six strong vibration modes were tested at random in the experimental analysis. The change and localization of the six modes are analyzed for each test. The results show that slight changes to the physical parameters are likely to induce remarkable changes and localization of some modal vectors in the RSSs.

FAULT DIAGNOSIS APPROACH FOR ROLLER BEARINGS BASED ON EMPIRICAL MODE DECOMPOSITION METHOD AND HILBERT TRANSFORM

Based upon empirical mode decomposition (EMD) method and Hilbert spectrum, a method for fault diagnosis of roller bearing is proposed. The orthogonal wavelet bases are used to translate vibration signals of a roller bearing into time-scale representation, then, an envelope signal can be obtained by envelope spectrum analysis of wavelet coefficients of high scales. By applying EMD method and Hilbert transform to the envelope signal, we can get the local Hilbert marginal spectrum from which the faults in a roller bearing can be diagnosed and fault patterns can be identified. Practical vibration signals measured from roller bearings with out-race faults or inner-race faults are analyzed by the proposed method. The results show that the proposed method is superior to the traditional envelope spectrum method in extracting the fault characteristics of roller bearings.

Relationship between the Local Vibration Mode Characteristics and the Charge State of Carbon Acceptor in GaAs

The local vibration mode(LVM)of carbon acceptor in GaAs is studied by measuring directly the change in LVM absorption with a NIC-170 SX FT-IR spectrometer.The change in the charge state of carbon acceptor and the temperature dependence of the LVM absorption were investigated also.The contents of the impurities other than carbon were estimated by secondary ion mass spectrometry.It is observed that the frequency,the spectral form and the integrated absorption of the LVM are not affected by the change in charge state of car- bon acceptor.

Impurity-induced local modes in one-dimensional dusty plasma chains

The effects of impurity on eigenmodes in one-dimensional dusty plasma lattices are studied. It is found that local modes can be excited besides lattice waves, due to the existence of an impurity particle. The dispersion relations of the modes are derived accordingly. Properties of the lattice and local modes are also analyzed and discussed, particularly for their symmetric features and conditions of the mode excitation.

Sideband Absorption and its Effects on Temperature Dependence of Local Vibrational Mode Main Absorption Band for Carbon Acceptor in Gallium Arsenide

The local vibrational mode (LVM) optical absorption band of carbon acceptor was investigated carefully. Because of the appearance of a sideband on the low energy side of the LVM main absorption band, it is found that the measured value of the integrated area for the main absorption band is sensitive to the choice of integration baseline wavenumber range (BWR). This is the main cause that the experimental results from different investigators show a wide spread for the temperature dependence of the integrated area. The origin of the sideband is also discussed.

A GEOMETRIC THEORY IN INVESTIGATION ON MODE LOCALIZATION AND FREQUENCY LOCI VEERING PHENOMENA

According to the mapping theory in complex plane, the geometric features of eigen frequency loci of systems undergoing free vibrations are investigated. It is concluded that the phenomena of curve coalescence and veering can be described in a unified manner from the singularities of mapping from the complex parameter plane onto the complex frequency plane. The formation of a branch point in the parameter Space is the foundation of explaining localization and veering phenomena. By the use of condensation to reduce the dimension of a system, the scope of application of the geometric theory is widely expanded. The theory is applied to examples to verify the validity of the proposed approach. The present work is an improvement and extension of recent work by M. S. Traintafyllou et al..

Analysis on the Development Trend of Contemporary Local Governance Mode from the perspective of Economic Policy and Environmental Capacity Optimization

As the basic level of national governance, local governance is deeply influenced by administrative tradition, political system and economic development level of a country. With more than thirty years of reform and opening up, the pattern of local governance has become diversified. The diversity of governance model cannot be managed in the same way, however, it cannot affect the government’s ability to play the initiative role of governance. We need to innovate and improve the existing local governance models.

Assessing the energy saving potential of using adaptive setpoint temperatures:The case study of a regional adaptive comfort model for Brazil in both the present and the future

It has been found in recent years that using setpoint temperatures based on adaptive thermal comfort models is a successful method of energy conservation.Recent studies using adaptive setpoint temperatures incorporate international models from ASHRAE Standard 55 and EN16798-1.This study,however,has instead considered a regional Brazilian adaptive comfort model.This study investigates the energy demand arising from the use of a local Brazilian comfort model in order to assess the energy implications from the use of the worldwide ASHRAE Standard 55 adaptive model and various fixed setpoint temperatures.All of Brazil’s climate zones,full air-conditioning,mixed-mode building operating modes,present-day climate change scenarios,and future scenarios—specifically Representative Concentration Pathways(RCP)2.6,4.5,and 8.5 for the years 2050 and 2100—have all been taken into account in building energy simulations.The use of adaptive setpoint temperatures based on the Brazilian local model considering mixed-mode has been found to significantly reduce energy consumption when compared to static setpoint temperatures(average energy-saving values ranging from 52%to 58%)and the ASHRAE 55 adaptive model(average values ranging from 15%to 21%).Considering climate change and the mixed-mode Brazilian model,the overall energy demand for the three groups of climatic zones(annual average outdoor temperatures≤21℃,>21 and≤25℃and>25℃)ranged between 2%decrease and 5%increase,4%and 27%increase,and 13%and 45%increase,respectively.It is concluded as a consequence that setting setpoint temperatures based on the Brazilian local adaptive comfort model is a very efficient energy-saving method.

基于三维精细化动力学模型的局部模态获取技术

Structural dynamic problems encountered within launch vehicles are sometimes related to entire dynamic characteristics of the vehicle,and sometimes related to local dynamic characteristics of some parts of vehicles.To acquire local dynamic characteristics,it usually requires the building of a three-dimensional detailed FEM model.It is important that the simulation of mass and stiffness of local part is accurate.The local mode acquisition of a gas tank and its bracket installed in the inter-tank section is taken as an example in this paper.It can be seen that the local modes are consistent with the section modal test results.Finally,the verified three-dimensional detailed FEM model of the inter-tank section is assembled within the entire launch vehicle,and the local modes of the gas tank and its bracket under flight conditions are predicted.

PHONONS IN POLYACENIC CHAINS

We have theoretically resolved phonon excitations in quasi-two-dimensional organic crystals of polyacenic semiconductor material which may be obtained by the pyrolytic treatment of phenol-formaldehyde resin. A model for studying the dynamical properties using three polyacene chains is proposed with the aim to present the vibrational properties of this structure. It employs the formalism of solid states in two dimensions which admit phonons. A simulation process of the two-dimensional lattice structure shows that elastic waves may explain the existence of vibrational modes in the frequency range 100-400 cm^-1. The presence of acoustic and optical like phonons is discussed in terms of the elastic force constants. A hyperfine resonance structure is obtained. It allows the analysis of the dynamical evolution in thin films of polyacene. It is found that the behavior of the phonon density of states exhibits resonance between modes in the structure.

Observation of chaotic ELMs in HL-2A tokamak

The high confinement mode （H-mode） operation is recently obtained in HL-2A divertor configuration, the corresponding edge localized mode （ELM） is recognized as being of type III. Time intervals in ELM time series are analysed to obtain the information about the ELM process. Signatures of unstable periodic orbits （UPOs） are detected, which are indicators of chaos and may be used to control the big ELM events.

Morphological and structural damage investigation of nanostructured molybdenum fuzzy surface after pulsed plasma bombardment

Steady high-flux helium(He)plasma with energy ranging from 50 eV to 90 eV is used to fabricate a fiber-form nanostructure called fuzz on a polycrystalline molybdenum(Mo)surface.Enhanced hydrogen(H)pulsed plasma in a wide power density range of 12 MW/m^(2)-35 MW/m^(2)is subsequently used to bombard the fuzzy Mo,thereby simulating the damage of edge localized mode(ELM)to fuzz.The comparisons of surface morphologies,crystalline structures,and optical reflectivity between the original Mo and the Mo treated with various He^(+)energy and transient power densities are performed.With the increase of He ion energy,the Mo nano-fuzz evolved density is enlarged due to the decrease of filament diameter and optical reflectivity.The fuzz-enhanced He release should be the consequence of crystalline growth and the lattice shrinkage inside the Mo-irradiated layers(^(2)00 nm).The fuzz induced by lower energy experiences more severe melting damage and dust release under the condition of the identical transient H plasma-bombardment.The H and He are less likely to be trapped due to aggravated melting evidenced by the enhanced crystalline size and distinct lattice shrinkage.As the transient power density rises,the thermal effect is enhanced,thereby causing the fuzz melting loss to aggravate and finally to completely disappear when the power density exceeds 21 MW/m^(2).Irreversible grain expansion results in huge tensile stress,leading to the observable brittle cracking.The effects of transient thermal load and He ion energy play a crucial role in etching Mo fuzz during ELM transient events.

Properties of plasma radiation during discharges with improved confinement on HL-2A Tokamak

In the recent experiment on the HL-2A tokamak, two types of improved confinement regimes have been achieved in different configurations. One is the improved confinement regime in limiter configuration during electron cyclotron resonant heating （ECRH）, characterized by a sharp decrease in Hα emission accompanied by an increase in the total radiation of plasma, the line averaged electron density and the stored energy of plasma. The other is high confinement regime （H-mode） in divertor configuration during a combination of ECRH and Neutral beam injection （NBI） heating, characterized with edge localized modes （ELMs） besides the features mentioned above. The ELMs are found to be localized on the plasma edge （r/a ≥ 0.8）, causing average losses of particles and stored energy in the ranges of about 1 3% and 3-5% respectively during a single ELM event. So far, the ELMs observed in the HL-2A are type Ⅲ ELMs with low amplitude and high repetition frequency in a range from 200 Hz to 350 Hz. An investigation of the radiated power density profiles shows that radiative cooling effect plays a significant role in the transition back to the L-mode and the triggering of ELM events.