基于非弹性位移响应谱值的框架结构易损性分析

为研究基于非弹性位移响应谱的框架结构易损性问题,通过有限元软件建立6个不同周期的钢筋混凝土框架模型,提出了框架结构损伤的4个极限状态的量化指标,采用IDA分析方法得到框架结构的易损性曲线;采用反应谱方法得到地震危险性曲线,进而得到框架结构抗震倒塌安全储备系数。本研究结果为今后评估框架结构的易损性问题提供参考。

Surface plasmon resonance-induced visible-light photocatalytic performance of silver/silver molybdate composites

Novel silver/silver molybdate（Ag/Ag2MoO4） composites with surface plasmon resonance（SPR）-enhanced photocatalytic performance were successfully fabricated via a facile one-pot hydrothermal route with the presence of sodium dodecyl sulfate（SDS） in this study.The as prepared silver/silver molybdate（Ag/Ag2MoO4） composites were systematically characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM） and ultraviolet-visible diffuse reflectance absorption spectroscopy（DRS） in order to investigate their crystal structure,morphology and optical property as well.The photocatalytic activities of the composites were subsequently evaluated by their ability to degrade rhodamine B（RhB） under visible-light irradiation.Varies of controlled experiments were then carefully operated to gain a deep insight into the assembling of Ag/Ag2MoO4composites.It was found that preparation conditions such as pH,reaction time,and the amount of surfactant played important roles in the formation of composites with octahedral microstructures.And the composite obtained at 160 ℃ using 0.5 g of sodium dodecyl sulfate exhibited the highest photocatalytic performance under visible-light irradiation.Capture experiments were also conducted to clarify the function of different active species generated on the surface of Ag/Ag2MoO4during the photocatalytic process,in which both holes and ·OH radicals were found to play crucial role in photocatalytic removal of RhB under visible light irradiation.A possible photocatalytic mechanism of Ag/Ag2MoO4 was finally proposed on the basis of all the results to explain the higher photocatalytic activity of the octahedral Ag/Ag2MoO4 composites.It was inferred that the photoinduced ＂hot＂ electrons can quickly transfer from the Ag NPs to the conduction band of Ag2MoO4 and react with oxygen and H2O to generate a large quality of active radicals such as ·OH and ·O2^- because of the SPR effects.Besides,this SPR effects of Ag nanoparticles deposited on the surface of Ag2MoO4 can not only dramatically amplify its light absorption,especially in the visible region,but also promote the separation of photoexcited electron-hole pairs and effectively decrease electron-hole recombination.

一种分析非均匀厚度1-3型压电复合材料换能器性能的方法

非均匀厚度1-3型压电复合材料可用于制作宽带压电换能器,已广泛应用于水浸无损探伤、声波测井以及超声成像等领域。为分析该换能器的振动及其性能,提出了一种并联振子等效电路模型,将非均匀厚度1-3型压电复合材料换能器看成并联的谐振器阵列,采用三维厚度伸缩振动模型对单个谐振器单元进行理论分析,得出了非均匀厚度1-3型压电复合材料换能器的阻抗计算公式;为验证该模型的正确性,设计并制作了一个平凹的1-3型压电复合材料换能器;实验结果显示,并联振子等效电路模型能准确的分析非均匀厚度1-3型压电复合材料片的性能。结果表明,非均匀厚度换能器带宽的主要是由压电片的厚度差异决定,研究结果可为非均匀厚度宽带换能器的设计提供参考。

基于非弹性位移的土-结构相互作用的抗震设计方法

基于等效线弹性系统位移的土-上部结构相互作用抗震设计方法中的不足,特别针对设计标准中关于相互作用系统等效阻尼比公式以及相关研究提供的设计步骤中存在的问题,提出了一个新的基于非弹性位移且考虑土-结构相互作用抗震设计方法。该方法将相互作用系统用一个等效单自由度理想弹塑性振子替代,并结合非弹性位移谱进行设计。给出了替代振子周期、阻尼比和延性比的公式和推导过程,以及与《建筑抗震设计规范》(GB50011—2010)中弹性位移谱相容的非弹性位移谱的建立方法和具体的设计步骤。并使用提出的公式对已有的基于弹性位移谱的设计方法进行了修正。将新方法与修正后的已有方法应用于具体的设计算例,通过非线性时程分析方法对设计结果进行验算。验算结果表明,基于非弹性方法的设计最大位移值比基于弹性方法的方案更接近时程分析结果。

Surface plasmon resonance effect of Ag nanoparticles for improving the photocatalytic performance of biochar quantum-dot/Bi_4Ti_3O_(12) nanosheets

Herein,we report a novel ternary material comprised of Ag nanoparticles and carbon quantum dots(CDs),which are co-loaded using 2D Bi4Ti3O12(BIT)sheets.In this system,Ag can be applied as excited electron-hole pairs in the Bi4Ti3O12 by transferring the plasmonic energy from the metal to the semiconductor.The surface plasmon resonance of Ag can promote the electron transfer properties of the CDs,thereby improving the separation efficiency of the electron-hole pairs.Meanwhile,the CDs can act as an electron buffer to decrease the recombination rate of the electron hole.Moreover,CDs are prepared using a biomaterial,which can provide a chemical group to enhance the electron transfer and connection.The synergistic effects of CDs,Ag,and BIT enable the design of a photocatalytic application with a remarkably improved efficiency and operational stability.

A Bi/BiOI/(BiO)_2CO_3 heterostructure for enhanced photocatalytic NO removal under visible light

Narrow-band BiOI photocatalysts usually suffer from low photocatalysis efficiency under visible light exposure because of rapid charge recombination. In this work, to overcome this deficiency of photosensitive BiOI, oxygen vacancies, Bi particles, and Bi2O2CO3 were co-induced in BiOI via a facile in situ assembly method at room temperature using NaBH4 as the reducing agent. In the synthesized ternary Bi/BiOI/(BiO)2CO3, the oxygen vacancies, dual heterojunctions (i.e., Bi/BiOI and Bi- OI/(BiO)2CO3), and surface plasmon resonance effect of the Bi particles contributed to efficient electron-hole separation and an increase in charge carrier concentration, thus boosting the overall visible light photocatalysis efficiency. The as-prepared catalysts were applied for the removal of NO in concentrations of parts per billion from air in continuous air flow under visible light illumination. Bi/BiOI/(BiO)2CO3 exhibited a highly enhanced NO removal ratio of 50.7%, much higher than that of the pristine BiOI (1.2%). Density functional theory calculations and experimental results revealed that the Bi/BiOI/(BiO)2CO3 composites promoted the production of reactive oxygen species for photocatalytic NO oxidation. Thus, this work provides a new strategy to modify narrow-band semiconductors and explore other bismuth-containing heterostructured visible-light-driven photocatalysts.

Novel indirect Z-scheme g-C3N4/Bi2MoO6/Bi hollow microsphere heterojunctions with SPR-promoted visible absorption and highly enhanced photocatalytic performance

The surface plasmonic resonance(SPR)effect of Bi can effectively improve the light absorption abilities and photogenerated charge carrier separation rate.In this study,a novel ternary heterojunction of g-C3N4/Bi2MoO6/Bi(CN/BMO/Bi)hollow microsphere was successfully fabricated through solvothermal and in situ reduction methods.The results revealed that the optimal ternary 0.4 CN/BMO/9 Bi photocatalyst exhibited the highest photocatalytic efficiency toward rhodamine B(RhB)degradation with nine times that of pure BMO.The DRS and valence band of the X-ray photoelectron spectroscopy spectrum demonstrate that the band structure of 0.4 CN/BMO/9 Bi is a z-scheme structure.Quenching experiments also provided solid evidence that the·O^2-(at-0.33 eV)is the main species during dye degradation,and the conduction band of g-C3N4 is only the reaction site,demonstrating that the transfer of photogenerated charge carriers of g-C3N4/Bi2 MoO 6/Bi is through an indirect z-scheme structure.Thus,the enhanced photocatalytic performance was mainly ascribed to the synergetic effect of heterojunction structures between g-C3N4 and Bi2MoO6 and the SPR effect of Bi doping,resulting in better optical absorption ability and a lower combination rate of photogenerated charge carriers.The findings in this work provide insight into the synergism of heterostructures and the SPR absorption ability in wastewater treatment.

ZnO nanorod decorated by Au-Ag alloy with greatly increased activity for photocatalytic ethylene oxidation

In recent years, the preservation of fruits and vegetables in cold storage has become an issue of increasing concern, ethylene plays a leading role among them. We found ZnO has the effect of degrading gaseous ethylene, however its effect is not particularly satisfactory. Therefore, we used simple photo-deposition procedure and low-temperature calcination method to synthesize Au, Ag, and Au Ag alloy supported ZnO to improve the photocatalytic efficiency. Satisfactorily, after ZnO loaded with sole Au or Ag particles, the efficiency of ethylene degradation was 17.5 and 26.8 times than that of pure ZnO, showing a large increase in photocatalytic activity. However, the photocatalytic stability of Ag/ZnO was very poor, because Ag can be easily photooxidized to Ag2O. Surprisingly, when ZnO was successfully loaded with the Au Ag alloy, not only the photocatalytic activity was further improved to 94.8 times than that of pure ZnO, but also the photocatalytic stability was very good after 10 times of cycles. Characterization results explained that the Au-Ag alloy NPs modified ZnO showed great visible-light absorption because of the surface plasmon resonance(SPR) effect. Meanwhile, the higher photocurrent density showed the effective carrier separation ability in Au Ag/ZnO. Therefore, the cooperative action of plasmonic Au Ag bimetallic alloy NPs and efficient carrier separation capability result in the outstanding photoactivity of ethylene oxidation. At the same time, the formation of the alloy produced a new crystal structure different from Au and Ag, which overcomes the problem of poor stability of Ag/ZnO, and finally obtains Au Ag/ZnO photocatalyst with high activity and high stability. This work proposes a new concept of using metal alloys to remove ethylene in actual production.

Gravitomagnetic Effects on Collective Plasma Oscillations in Compact Stars

The effects of gravitomagnetic force on plasma oscillations are investigated using the kinetic theory of homogeneous electrically neutral plasma in the absence of external electric or magnetic field. The random phase assumption is employed neglecting the thermal motion of the electrons with respect to a fixed ion background. It is found that the gravitomagnetic force reduces the characteristic frequency of the plasma thus enhancing the refractive index of the medium. The estimates for the predicted effects are given for a typical white dwarf, pulsar, and neutron star.

Synthesis of novel CaCO_3/Ag_2CO_3/Ag I/Ag plasmonic photocatalyst with enhanced visible light photocatalytic activity.

In this work, novel CaCO3/Ag2CO3/AgI/Ag plasmonic photocatalysts were successfully synthesized by a two-step in situ ion exchange process and their photocatalytic properties were studied. The morphology, crystal structure and optical properties of the as-prepared CaCO3/Ag2CO3/AgI/Ag nanocomposites were characterized by transmission electron microscopy （TEM）, X- Ray diffraction （XRD）, and UV-vis diffuse reflectance spectroscopy. The photocatalytic activity of the obtained nanocomposites was evaluated by the photodegradation of methyl orange （MO） under visible light irradiation. It was found that the as-prepared CaCO3/Ag2CO3/AgI/Ag plasmonic photocatalyst exhibits high visible light photocatalytic activity. With an optimized composition, MO dye can be decomposed by more than 94% within 15 min under visible light irradiation. Moreover, the photocatalytic stability could be greatly improved upon the addition of Na2CO3 into the photocatalytic system. From the proposed photocatalytic mechanism, the strong surface plasmon resonance effect of Ag nanoparticles and the efficient separation of photogenerated electrons and holes can effectively enhance the photocatalytic performance of the CaCO3/Ag2COj AgI/Ag composites.

Flower-like Bi^0/CeO2-δ plasmonic photocatalysts with enhanced visible-light-induced photocatalytic activity for NO removal

Plasmonic bismuth(Bi^0)nanoparticle-decorated flower-like CeO2-δ(Bi^0/CeO2-δ)photocatalysts with abundant oxygen vacancies(OVs)were synthesized via a solvothermal method.The OVs can not only improve the separation of electron-hole pairs,but also facilitate the adsorption and activation of gas molecules(NO/O2).In addition,the Bi^0 nanoparticles can enhance the visible light response and prevent the recombination of charge carriers by virtue of the surface plasmon resonance(SPR)effect,achieving an excellent ability for NO elimination and NO2 inhibition under visible light irradiation.Density functional theory(DFT)calculations confirm that the Schottky barrier between Bi^0 and CeO2-δaccompanied with the OVs are pivotal for the migration of photogenerated charge carriers to involve in the photocatalytic NO removal.Trapping experiments and in situ FTIR spectroscopy were conducted to explore the mechanism of the photocatalytic NO removal,suggesting that the photocatalytic NO removal can be significantly enhanced by introducing abundant OVs and the involvement of Bi^0 metal nanoparticles.

Performance Evaluation of a Bilayer SPR-Based Fiber Optic RI Sensor With TiO2 Using FDTD Solutions

We proposed a new bilayer surface plasmon resonance-based fiber-optic refractive index sensor with silver and an over-layer of TiO2. We numerically investigated the optimal thickness of TiO2 over-layer in the proposed sensor and compared its performance to that based on typical bimetallic layers of silver-and-gold in the aqueous media using finite-difference time domain approach. We show that the use of TiO2 over-layer greatly improves the sensor performance in terms of sensitivity and signal-to-noise ratio compared to that with gold as the over-layer. Not only does the TiO2 over-layer offer a cost-effective alternative to gold for overcoming the oxidation problem, but also it allows resonance wavelength-tunability.

Nanoscopic Tip Sensors Fabricated by Gas Phase Etching of Optical Glass Fibers

Silica-based fiber tips are used in a variety of spectroscopic, micro- or nano-scopic optical sensor applications and photonic micro-devices. The miniaturization of optical sensor systems and the technical implementation using optical fibers can provide new sensor designs with improved properties and functionality for new applications. The selective-etching of specifically doped silica fibers is a promising method in order to form complex photonic micro structures at the end or within fibers such as tips and cavities in various shapes useful for the all-fiber sensor and imaging applications. In the present study, we investigated the preparation of geometrically predefined, nanoscaled fiber tips by taking advantage of the dopant concentration profiles of highly doped step-index fibers. For this purpose, a gas phase etching process using hydrofluoric acid （HF） vapor was applied. The shaping of the fiber tips was based on very different etching rates as a result of the doping characteristics of specific optical fibers. Technological studies on the influence of the etching gas atmosphere on the temporal tip shaping and the final geometry were performed using undoped and doped silica fibers. The influence of the doping characteristics was investigated in phosphorus-, germanium-, fluorine- and boron-doped glass fibers. Narrow exposed as well as protected internal fiber tips in various shapes and tip radiuses down to less than 15 nm were achieved and characterized geometrically and topologically. For investigations into surface plasmon resonance effects, the fiber tips were coated with nanometer-sized silver layers by means of vapour deposition and finally subjected to an annealing treatment.

Electromagnetically Induced Transparency of Two Intense Circularly-Polarized Lasers in Cold Plasma: Beat-Wave Second Harmonic Effect

In the present paper the problem of nonlinear interaction of two mildly-relativistic circularly polarized lasers in a cold plasma is studied in order to investigate electromagneticaily induced transparency （EIT）. Based on a relativistic kinetic model, by expansion of relativistic Lorentz factor in terms of lasers amplitude, we obtain the coupled nonlinear dispersion relations. It is observed that due to resonance in the second harmonic of plasma beat-wave, the new EIT pass-band is created in the high intensities of lasers. The effect of amplitude and frequency variation on the dispersion is numerically investigated.