External blast flow field evolution and response mechanism of single-layer reticulated dome structure

Single-layer reticulated dome structure are commonly high-profile building in the public and can be attractive targets for terrorist bombings,so the public can benefit from enhanced safety with a stronger understanding of the behavior of single-layer reticulated dome structure under explosion.This paper investigates the fluid-structure interaction process and the dynamic response performance of the singlelayer reticulated dome under external blast load.Both experimental and numerical results shown that structural deformation is remarkably delayed compared with the velocity of blast wave,which advises the dynamic response of large-span reticulated dome structure has a negligible effect on the blast wave propagation under explosion.Four failure modes are identified by comparing the plastic development of each ring and the residual spatial geometric of the structure,i.e.,minor vibration,local depression,severe damage,and overall collapse.The plastic deformation energy and the displacement potential energy of the structure are the main consumers of the blast energy.In addition,the stress performance of the vertex member and the deep plastic ratio of the whole structure can serve as qualitative indicators to distinguish different failure modes.

Sensitivity analysis and probability modelling of the structural response of a single-layer reticulated dome subjected to an external blast loading

The structural response of a single-layer reticulated dome to external explosions is shaped by many variables,and the associated uncertainties imply non-deterministic results.Existing deterministic methods for predicting the consequences of specific explosions do not account for these uncertainties.Therefore,the impact of the uncertainties associated with these input variables on the structures’response needs to be studied and quantified.In this study,a parametric uncertainty analysis was conducted first.Then,local and global sensitivity analyses were carried out to identify the drivers of the structural dynamic response.A probabilistic structural response model was established based on sensitive variables and a reasonable sample size.Furthermore,some deterministic empirical methods for explosion-resistance design,including the plane blast load model of CONWEP,the curved blast load model under the 50%assurance level,and the 20%mass-increased method,were used for evaluating their reliability.The results of the analyses revealed that the structural response of a single-layer reticulated dome to an external blast loading is lognormally distributed.Evidently,the MB0.5 method based on the curved reflector load model yielded results with a relatively stable assurance rate and reliability,but CONWEP did not;thus,the 1.2MB0.5 method can be used for making high-confidence simple predictions.In addition,the results indicated that the structural response is very sensitive to the explosion parameters.Based on these results,it is suggested that for explosion proofing,setting up a defensive barrier is more effective than structural strengthening.

Lower Bounds of Decay Rates for Solution to the Single-Layer Quasi-Geostrophic Model

In this paper, we study the long-time behavior of solutions of the single-layer quasi-geostrophic model arising from geophysical fluid dynamics. We obtain the lower bound of the decay estimate of the solution. Utilizing the Fourier splitting method, under suitable assumptions on the initial data, for any multi-index α, we show that the solution Ψ satisfies .

Failure Modes for Single-Layer Reticulated Domes Under Impact Loads

The paper presents the theory of Hamilton variation principle which is the current method for impact problem, central difference method which is efficient solution of finite element (FE) method for impact problem and adapts to solve non-linear dynamic problem. And it introduces the ANSYS/LS-DYNA which is the popular FE software for impact problem both at home and abroad. Then it gives solutions for one simple model by analytical method and ANSYS/LS-DYNA respec-tively to validate function of software, and they are consistent. Afterward, it gives model of single-layer Kiewitt reticulated dome with a span of 60 m, and the cylinder impactor, and introduces the contact interface arithmetic, especially the material model of steel (piecewise linear plasticity model) which takes stain rate into account and makes steel failure stress higher under impact loads. The vertical displacement, stress in main members, and the plastic deformation for dome under impact loads were obtained. Then four failure modes (no failure, moderate failure, global failure and slight failure) were summarized according to the rules of dynamic response. And the characteristics of dynamic response for each failure mode were shown.

Failure Process and Energy Transmission for Single-Layer Reticulated Domes Under Impact Loads

No failure, moderate failure, severe failure, and slight failure are the four failure modes generalized observed in the dynamic response of the single-layer reticulated dome under vertical impact load on apex. TE (the time that the end of impact force) and TF (the time that members are broken) are two key times in the failure process. Characteristics of dynamic responses at the two key times are shown in order to make the failure mechanism clear. Then three steps of energy transfer are summarized, i.e. energy applying, energy loss and energy transfer, energy consump-tion. Based on the three steps, energy transfer process for the failure reticulated dome under once impact is introduced. Energy transmissibility and local loss ratio are put forward firstly to obtain EL F(the energy left in the main reticulated dome) from the initial kinetic energy of impactor. More-over, the distribution of failure modes is decided by EL F which leads to the maximum dynamic re-sponse of the reticulated dome, but not by the initial impact kinetic energy of impactor.

Damage mechanism of single-layer reticulated domes under severe earthquakes

To study the damage mechanism of single-layer reticulated domes subject to severe earthquakes, three limit states of single-layer reticulated domes under earthquakes are defined firstly in this paper. Then, two failure modes are presented by analyzing damage behaviors, and their characteristics are pointed out respectively. Furthermore, the damage process is analyzed and the causes of structural damage in different levels are studied. Finally, by comparing deformation and vibration status of domes with different failure modes, the principles of different failures are revealed and an integrated frame of damage mechanism is set up.

Preliminary analysis of mode truncation of single-layered reticulated domes under earthquakes

In anti-seismic calculation, the mode truncation is a significant problem to engineers if the mode-superposition response spectrum method is used, which has not been completely solved yet in some large and complex structures such as reticulated domes. In this case, some useful advices, concentrating on the problem above, are expected through a careful and comprehensive investigation of this paper. During the investigation, the authors first point out shortcomings of former researches. Then frequency-spectrum characteristics of single-layered reticulated domes were studied from the perspective of structural responses. During this process, some important results such as the existence of the main resonant section, and the fact that the relative sensitivity of these domes under horizontal and vertical impulse varies with the different R/S ratios were achieved. Furthermore, based on the study of frequency-spectrum characteristics, as well as that of earthquake input, reasonable numbers of mode truncation in single layered reticulated domes with different R/S ratio were presented. Results of case studies prove the mode truncation number proposed is valid.

Superconducting Single-Layer T-Graphene and Novel Synthesis Routes

Single-layer superconductors are ideal materials for fabricating superconducting nano devices.However,up to date,very few single-layer elemental superconductors have been predicted and especially no one has been successfully synthesized yet.Here,using crystal structure search techniques and ab initio calculations,we predict that a single-layer planar carbon sheet with 4-and 8-membered rings called T-graphene is a new intrinsic elemental superconductor with superconducting critical temperature(Tc)up to around 20.8 K.More importantly,we propose a synthesis route to obtain such a single-layer T-graphene,that is,a T-graphene potassium intercalation compound(C4 K with P4/mmm symmetry)is firstly synthesized at high pressure(>11.5 GPa)and then quenched to ambient condition;and finally,the single-layer T-graphene can be either exfoliated using the electrochemical method from the bulk C4 K,or peeled off from bulk T-graphite C4,where C4 can be obtained from C4 K by evaporating the K atoms.Interestingly,we find that the calculated Tc of C4 K is about 30.4 K at 0 GPa,which sets a new record for layered carbon-based superconductors.The present findings add a new class of carbon-based superconductors.In particular,once the single-layer T-graphene is synthesized,it can pave the way for fabricating superconducting devices together with other 2 D materials using the layer-by-layer growth techniques.

Dynamic behavior of single-layer latticed cylindrical shells subjected to seismic loading

The single-layer latticed cylindrical shell is one of the most widely adopted space-fl'amed structures.In this paper,free vibration properties and dynamic response to horizontal and vertical seismic waves of single-layer latticed cylindrical shells are analyzed by the finite element method using ANSYS software.In the numerical study,where hundreds of cases were analyzed,the parameters considered included rise-span ratio,length-span ratio,surface load and member section size.Moreover,to better define the actual behavior of single-layer latticed shells,the study is focused on the dynamic stress response to both axial forces and bending moments.Based on the numerical results,the effects of the parameters considered on the stresses are discussed and a modified seismic force coefficient method is suggested.In addition,some advice based on these research results is presented to help in the future design of such structures.

Ultra-thin circularly polarized lens antenna based on single-layered transparent metasurface

Circularly polarized （CP） lens antenna has been applied to numerous wireless communication systems based on its unique advantages such as high antenna gain, low manufacturing cost, especially stable data transmission between the transmitter and the receiver. Unfortunately, current available CP lens antennas mostly suffer from high profile, low aperture efficiency as well as complex design. In this paper, we propose an ultra-thin CP lens antenna based on the designed single- layered Pancharatnam-Berry （PB） transparent metasurface with focusing property. The PB metasurface exhibits a high transmissivity, which ensures a high efficiency of the focusing property. Launched the metasurface with a CP patch antenna at its focal point, a low-profile lens antenna is simulated and measured. The experimental results show that our lens antenna exhibits a series of advantages including high radiation gain of 20.7 dB, aperture efficiency better than 41.3%, and also narrow half power beam width （HPBW） of 13°at about 14GHz. Our finding opens a door to realize ultra-thin transparent metasurface with other functionalities or at other working frequencies.

Single-layer graphene as a highly selective barrier for vanadium crossover with high proton selectivity

We report near-zero crossover for vanadium cross-permeation through single-layer graphene immobilized at the interface of two Nafion?polymer electrolyte membranes.Vanadium ion diffusion and migration,including proton mobility through membrane composites,were studied with and without graphene under diffusion and migration conditions.Single-layer graphene was found to effectively inhibit vanadium ion diffusion and migration under specific conditions.The single-layer graphene composites also enabled remarkable ion transmission selectivity improvements over pure Nafion membranes,with proton transport being four orders of magnitude faster than vanadium ion transport.Resistivity values of 0.02±0.005Ωcm^(2) for proton and 223±4Ωcm^(2) for vanadium ion through single atomic layer graphene are reported.This high selectivity may have significant impact on flow battery applications or for other electrochemical devices where proton conductivity is required,and transport of other species is detrimental.Our results emphasize that crossover may be essentially completely eliminated in some cases,enabling for greatly improved operational viability.

Gap opening and tuning in single-layer graphene with combined electric and magnetic field modulation

The energy band structure of single-layer graphene under one-dimensional electric and magnetic field modulation is theoretically investigated. The criterion for bandgap opening at the Dirac point is analytically derived with a two-fold degeneracy second-order perturbation method. It is shown that a direct or an indirect bandgap semiconductor could be realized in a single-layer graphene under some specific configurations of the electric and magnetic field arrangement. Due to the bandgap generated in the single-layer graphene, the Klein tunneling observed in pristine graphene is completely suppressed.

Nanoscale mass sensing based on vibration of single-layered graphene sheet in thermal environments

Based on vibration analysis, single-layered graphene sheet （SLGS） with multiple attached nanoparticles is developed as nanoscale mass sensor in thermal environments. Graphene sensors are assumed to be in simplysupported configuration. Based on the nonlocal plate the- ory which incorporates size effects into the classical theory, closed-form expressions lot the frequencies and relative fre- quency shills of SLGS-based mass sensor are derived using the Galerkin method. The suggested model is justified by a good agreement between the results given by the present model and available data in literature. The effects of tem- perature difference, nonlocal parameter, the location of the nanoparticle and the number of nanoparticles on the relative frequency shift of the mass sensor are also elucidated. The obtained results show that the sensitivity of the SLGS- based mass sensor increases with increasing temperature difference.

南极Dome A地区低温低压环境下智能照明控制技术探索

南极内陆Dome A地区极端恶劣的环境对科考人员的生理极限及作业效率构成了严峻挑战,而无人观测站可突破人类生理限制,持续高效工作,其关键运维技术,包括智能照明控制技术等越发受到各国重视。本文在总结Dome A地区遥远、低温、极夜、白化天等不利影响因素的基础上,探索适应该区域极端环境、满足科考人员工作需求、便于远程及现场操作的智能照明系统运维模式,进行满足极昼极夜环境下无人观测站室内监测及维护需求的智能照明适宜技术选型。通过对铱星传输模块、Wi-Fi无线网关等子系统的组合,提出可耐受Dome A地区低温低压环境的现场照明监控设备控制方案,对南极无人站区的建设及相关智能照明控制技术的发展具有指导意义。

Theoretical Proposal for a Planar Single-Layer Carbon That Shows a Potential in Superconductivity

Single-layer superconductors[1]have been the subject of considerable interests as they are ideal systems for the fundamental understanding of two-dimensional(2D)physics and for device applications.A few singlelayer superconductors are experimentally achieved(e.g.,FeSe,MoS2,and NbSe2[2-4]in the field where either charge doping or tensile strain is often required to promote the superconductivity.

Pseudohalide induced tunable electronic and excitonic properties in two-dimensional single-layer perovskite for photovoltaics and photoelectronic applications

Two-dimensional(2D) layered organic-inorganic hybrid perovskites have attracted much more attention for some applications than their three-dimensional(3D) perovskite counterparts due to their promising thermal and moisture stabilities.In particular, the 2D perovskite devices have shown better promise for optoelectronic applications.However, tunability of optoelectronic properties is often demanded to improve the device performance.Herein, we adopt a newly method to tune the electronic properties of 2D perovskite by introducing pseudohalide into the structure.In this work, we designed a pseudohalidesubstituted 2D perovskite by substituting the out-of-plane halide with pseudohalide and studied the electronic and excitonic properties of 2D-BA2MX4 and 2D-BA2MX2Ps2(M=Ge^(2+), Sn^(2+), and Pb^(2+);X=I;Ps=NCO, NCS, OCN, SCN, Se CN).We revealed the dependence of electronic properties including band gaps, composition of band edges, bonding characteristics, work functions, effective masses, and exciton binding energies on different pseudohalides substituted in 2D perovskite.Our results indicate that the substitution of pseudohalide in 2D perovskites is energetically favorable and can significantly affect the bonding characteristics as well as the CBM and VBM that often play major role in determining their performance in optoelectronic devices.It is expected that the pseudohalide substitution will be helpful in developing more advanced optoelectronic device based on 2D perovskite by optimizing band alignment and promoting charge extraction.

Electronic Structures and Optical Properties of Ga Doped Single-Layer Indium Nitride

Electronic structures and optical properties of single-layer In1-xGaxN are studied by employ-ing Heyd-Scuseria-Ernzerh(HSE)method based on the first-principles.The band structure and density of states(DOS)of single-layer In1-xGaxN are calculated,and the band gap ranges from 1.8 eV to 3.8 eV as the ratio x changes,illustrating the potential for the tun-ability of band gap values via Ga doped.We also have investigated optical properties of single-layer In1-xGaxN such as dielectric function,refractive index and absorption coeficient,the main peak of dielectric function spectrum and the absorption edge are found to have a remarkable blue-shift as the concentration of Ga increases.Furthermore,the optical properties of single-layer In1-xGaxN are analyzed based on the band structures and DOS analysis.Such unique optical properties have profound application in nanoelectronics and optical devices.

Deposition mechanism of nano-structured single-layered C_(36) film on a diamond (100) crystal plane

The Brenner-LJ potential is adopted to describe the interaction between C36 clusters and diamond surface, and the deposition mechanism of multi-C36 clusters on the diamond surface is also studied by using the method of molecular dynamics simulation. The simulation results show that the competition effects of two interactions, i.e. the interaction between cluster and cluster and the interaction between cluster and crystal plane, are studied, and then the influence of these competition effects on C36 cluster deposition is analysed. The finding is that when an incident energy is appropriately chosen, C36 clusters can be chemically adsorbed and deposited steadily on the diamond surface in the form of single-layer, and in the deposition process the multi-C36 clusters present a phenomenon of energy transmission. The experimental result shows that at a temperature of 300K, in order to deposit C36 clusters into a steady nanostructured single-layered film, the optimal incident energy is between 10 and 18 eV, if the incident energy is larger than 18 eV, the C36 clusters will be deposited into an island nano-structured film.

On hydraulic falls of single-layer flow

Hydraulic falls of single-layer now are determined theoretically in terms of a time-dependent averaged fKdV equation(AfKdV equation)in phase coordinate. From the theory of the present paper it was known that difference of the asymptotic mean levels upstream and downsream at the subcritical cutoff points is just equal to a subcritical value of the AfKdV equation An experiment is carried out to examine the theoretical results. From comparison between theoreticaland experimental results, it was shown that they are in good agreement.At the same time, it should be pointed out that the theory of the present paper is agreement with the experimental and numerical results of Forbes and can be employed to find the generating properties of the precursor solitons at near-resonance.

Magnetic phase diagram of single-layer CrBr_(3)

We theoretically provide a magnetic phase diagram for the single-layer(SL)CrBr_(3),which could be effectively tuned by both strain engineering and charge doping in SL-CrBr_(3).Through systematical first-principles calculations and Heisenberg model Hamiltonian simulations,three different magnetic phases in SL-CrBr_(3),which are off-plane ferromagnetic,in-plane ferromagnetic and in-plane Neél-antiferromagnetic phases,are found in the strain and charge doping regimes we studied.Furthermore,our results show that higher order Heisenberg exchange parameters and anisotropy exchange parameters should be taken into account for accurately illustrating the magnetic phase transition in SL-CrBr_(3).As a result,we find from the SpinW simulation that the Curie temperature is about T_(c)=38.4 K,which is well consistent with the experimental result 34 K[Nano Lett.193138(2019)].The findings here may be confirmed in future experiments,and may be useful for the potential applications of SL-CrBr_(3)in spintronics field.