加固后钢筋混凝土十字形柱斜向抗震性能研究

钢筋混凝土十字形柱的斜向抗震性能是影响结构安全性能的重要因素。文章设计了3种新型约束补强方式加固的钢筋混凝土十字形柱试件,在验证有限元建模方法有效性的基础上模拟了斜向低周往复加载,通过分析试件的滞回曲线、骨架曲线、承载力和延性等抗震性能指标研究了试件的斜向抗震性能,并参考相关规范得出了新型约束补强方式十字形柱的压弯承载力计算公式。结果表明:钢筋网格局部加强使试件的斜向峰值位移提高了7.4%~19.4%;柱端嵌贴碳纤维布(Carbon Fiber Reinforced Polymer,CFRP)板条会使试件峰值承载力、延性系数分别提高了约29.2%~34.2%和7.5%~22.9%;柱端嵌贴CFRP板使试件斜向峰值承载力、延性系数分别提高了约99.9%~105.5%和17.4%~24.8%。3种加固方式均可改善钢筋混凝土十字形柱的斜向抗震性能,改善程度由大到小依次为柱端嵌贴CFRP板、柱端嵌贴CFRP板条和钢筋网格局部加强。

SLAT在T细胞发育分化中的研究进展

SLAT是一类高表达于胸腺细胞和外周血T细胞的接头蛋白分子,在抗原刺激下可活化下游的RhoGTP酶,控制细胞内Ca2+增加和细胞信号转导;SLAT通过其GEF调节NFAT活化,同时通过TCR信号途径调控T细胞生长发育及分化,在T细胞免疫应答中扮演着重要的角色。本文就SLAT的结构、功能及其在T细胞发育分化的研究进展做一综述。

装配式建筑施工技术深化应用研究

分析了国内外装配式建筑发展现状,阐明装配式建筑的优势,指出装配式建筑发展限制因素,并提出窗口深化设计、预留钢筋定位、ALC条板墙深化拼接等措施,解决装配式建筑常见的部分质量问题。通过技术创新提高建筑水平及装配式建筑品质,以期更好地优化装配式建筑的局部细节处理。

Longitudinal impedance measurements and simulations of a three-metal-strip kicker

A kicker is a critical component for beam injection and accumulation in circular particle accelerators. A ceramic slat kicker plated with a TiN conductive coating was applied in the Beijing Electron Positron Collider (BEPCII). However, the ceramic slat kicker has experienced several sudden malfunctions during the operation of the BEPCII in the past. With a reliable kicker structure, a three-metal-strip kicker can substitute the original ceramic slat kicker to maintain the operational stability of the BEPCII. A comparison of the numerical simulation was conducted for three kicker models, demonstrating the comprehensive advantage of the three-metal-strip kicker. Furthermore, impedance bench measurements were conducted on a prototype of a three-metal-strip kicker. The longitudinal beam-coupling impedance was measured using a vector network analyzer via the coaxial wire method. A satisfactory agreement was obtained between the numerical simulations and measurements. Based on the numerical simulation data, the loss factor was 0.01721 V/pC, and the effective impedance was 3.59 mΩ(σ=10 mm).The simulation of the heat deposition on each part of the kicker demonstrated that 84.4%of the parasitic loss of the beam was deposited on the metal strips, and the total heat deposition power on the kicker was between 113.3 and 131.5 W. The obtained heat deposition powers can be considered as a reference for establishing the cooling system.

脐血CD34^+细胞分化为树突状细胞过程中JAK2、STAT5蛋白的表达及活化

目的 检测脐血CD3 4+ 造血干 祖细胞分化为树突状细胞过程中JAK2、STAT5蛋白的表达及活化 ,从而了解JAK STAT信号途径在CD3 4+ 造血干 祖细胞向DC分化中的作用。方法 体外诱导脐血CD3 4+ 细胞向DC分化 ,用免疫印迹方法检测CD3 4+ 细胞、分化第 7天细胞和分化第 14天的细胞中与GM CSF密切相关的JAK2和STAT5蛋白的表达及其在GM CSF作用下蛋白酪氨酸磷酸化水平。结果 分离的CD3 4+ 细胞和诱导分化第 7天、第 14天的细胞在正常静止状态下 ,均表达一定量的JAK2 ,而且在所有的时间点JAK2蛋白的表达量类似 ,随着细胞向DC分化酪氨酸磷酸化JAK2水平明显增加 ;STAT5在CD3 4+ 细胞分化前即有明显表达 ,随着向DC分化 ,其表达量增加。随着DC的分化成熟 ,STAT5的酪氨酸磷酸化水平提高。STAT5的活化高峰较JAK2的酪氨酸磷酸化滞后。结论 JAK STAT途径可能参与了GM CSF刺激作用下CD3 4+

Aerodynamic and Acoustic Optimization for Multi-element Airfoils

The paper is to integrate aerodynamic and aero-acoustic optimizatiom design of high lift devices,especially for two-element airfoils with slat.Aerodynamic analysis on flow field utilizes a high-order,high-resolution spatial differential method for large eddy simulation(LES),which can guarantee accuracy and efficiency.The aeroacoustic analysis for noise level is calculated with Ffowcs Williams-Hawkings(FW-H)integration formula.Fidelity of calculation is verified by standard models.Method of streamline-based Euler simulation(MSES)is used to obtain the aerodynamic characters.Based on the confirmation of numerical methods,detailed research has been conducted for the leading edge slat on multi-element airfoils.Various slot parameter influences on noise are analyzed.The results of the slot optimization parameters can be used in multi-element airfoil design.

水下等离子切割水台的制作

介绍了水下等离子切割水台的基本结构、主要技术规格、工作特点、制造质量控制以及使用时的注意事项。

Slat cove dynamics of multi-element airfoil at low Reynolds number

The flow around the slat cove of a two-dimensional 30P30N multi-element airfoil is investigated with time-resolved particle image velocimetry(TR-PIV)at low Reynolds number(Rec=2.41×10^(4)and 4.61×10^(4)).The effects of angle of attack(α=8°,12°,and 16°)on the mean flow characteristics and vortex dynamics are discussed.The size of the recirculation within the slat cove and the intensity of the shed vortices originating from the slat cusp shear layer are found to generally decrease as the angle of attack increases.The joint time-frequency analyses show that disturbances of different frequencies exist in the slat cusp shear layer and they trigger the different vortex shedding patterns of the slat cusp shear layer.The self-sustained oscillation within the slat cove,normally observed at high Reynolds number(Re_(c)~10^(6)),is proved to be responsible for the disturbances of different frequencies and the related vortex dynamics in the current study.

High-Lift Effect of Bionic Slat Based on Owl Wing

A slat without a cove is built on the basis of a bionic airfoil （i.e. stowed multi-element airfoil）, which is extracted from a long-eared owl wing. The three-dimensional models with a deployed slat and a stowed slat are measured in a low-turbulence wind tunnel. The results are used to characterize high-lift effect： compared with the stowed slat, the deployed slat works more like a spoiler at low angles of attack, but like a conventional slat or slot at high angles of attack. In addition, it can also increase stall angle and maximum lift coefficient, and postpone the decrease in the gradient of the lift coefficient. At the same time, the flow field visualized around both three-dimensional models suggests the leading-edge separation associated with the decrease in the gradient of the lift coefficient, Furthermore, the related two-dimensional simulation well agrees with the analysis of the lift coefficient, as the complement to the experiment. The bionic slat may be used as reference in the design of leading-edge slats without a cove.

Reliability and global sensitivity analysis for an airplane slat mechanism considering wear degradation

This paper focuses on the issue of reliability and global sensitivity analysis for an airplane slat mechanism considering the uncertainties in the wear process of mechanical components.First,the multi-body kinematic model of the slat mechanism is built in the ADAMS software.The geometrical sizes of the roller wheels after wear degradation are considered as input variables and the angle the slat should turn is considered as the output response.To accurately identify the influential roller wheels to the reliability and robustness of the slat mechanism,the failure probability based sensitivity and variance-based sensitivity indices are introduced.Comprehensive analysis of the results have shown that the reliability analysis and global sensitivity theory can help engineers find significant parts by their contributions,thus provide guidance for mechanical design and maintenance.

Tunable terahertz filter based on alternative liquid crystal layers and metallic slats

We propose and demonstrate a pseudo Fabry–Pérot filter in the terahertz frequency range of 0.1–0.5 THz. It consists of alternative liquid crystal layers and metallic slats. Separate sharp resonant peaks are shown in the simulated transmission spectra, and their positions shift toward higher frequencies when the refractive index of liquid crystal decreases. The measured transmission spectra are consistent with corresponding simulations. Via thermally tuning the refractive index of the filled liquid crystal, the resonant transmission frequencies shift accordingly. The work supplies a novel design for tunable terahertz filters, which would play important roles in terahertz imaging, sensing, high speed communication, and security applications.

Effects of inductive methods on dunging behavior of weaning pigs in slatted floor pens

The excreta of pig is generally utilized to induce pigs to excrete in particular area,which reduces the subsequent work required to clean pens.This paper discussed a new induction device design based on the biological characteristics of pigs.Using different induction materials in the devices,the frequency and location of the excretory behavior of pigs through five treatments and a control group were compared.According to the results,different induction methods had significant(p<0.05)effects on frequency and duration of excretory behavior.Compared to the conventional induction method,the induction devices were significantly(p<0.05)more effective in training pigs to excrete in the assigned area,the most effective material used in the induction devices was feces.If the inductive feces had been preserved in the air for a longer time,the effect of inducing excretory behavior would have been more obvious.Empty devices did not work to induce pigs to excrete in the induction area.

Slat Noise Suppression Using Upstream Mass Injection

A new approach,mass injection near the slat cusp,is proposed for the suppression of slat noise.The mechanism and efciency of the slat noise suppression using upstream mass injection are numerically studied with hybrid Reynolds-averaged Navier-Stokes simulation/Large eddy simulation(RANS/LES)of a three-component high-lift model.Ffowcs-Williams and Hawking(FW-H)integration is employed to obtain far-field acoustic characteristics.Results show that with injection,aerodynamic capability of the high-lift devices is sustained.In addition,a considerable noise reduction is observed in the downward direction.With detailed analysis of the time-averaged and instantaneous flow fields,two mechanisms are identified as the reason accounting for the noise suppression:upstream mass injection significantly reduces the scale and strength of the vortices stemming from the cusp;the shear layer is lifted up,which relieves the shear layer impingement on the slat lower surface.

An artificial neural network approach for aerodynamic performance retention in airframe noise reduction design of a 3D swept wing model

With the progress of high-bypass turbofan and the innovation of silencing nacelle in engine noise reduction, airframe noise has now become another important sound source besides the engine noise. Thus, reducing airframe noise makes a great contribution to the overall noise reduction of a civil aircraft. However, reducing airframe noise often leads to aerodynamic performance loss in the meantime. In this case, an approach based on artificial neural network is introduced. An established database serves as a basis and the training sample of a back propagation （BP） artificial neural network, which uses confidence coefficient reasoning method for optimization later on. Then the most satisfactory configuration is selected for validating computations through the trained BP network. On the basis of the artificial neural network approach, an optimization pro- cess of slat cove filler （SCF） for high lift devices （HLD） on the Trap Wing is presented. Aerody- namic performance of both the baseline and optimized configurations is investigated through unsteady detached eddy simulations （DES）, and a hybrid method, which combines unsteady DES method with acoustic analogy theory, is employed to validate the noise reduction effect. The numerical results indicate not merely a significant airframe noise reduction effect but also excellent aerodynamic performance retention simultaneously.

Effect of structure parameters on forces acting on baffles used in gas-solids fluidized beds

Effects of some important structural parameters,i.e.slat pitch,and layout position,on dynamic forces acting on the baffles were examined in the fluidized bed of FCC particles operating under different superficial gas velocities.The experimental baffles were made of multiple inclined slats.We found that the forces acting on the baffles decreased significantly with reducing pitch between the slats.For the baffles with a small slat pitch,the forces acting on the baffles increased slightly and then decreased with increasing superficial gas velocity,which is very different from the measured results of a single slat or tube immersed in fluidized beds.The different results are greatly related to the appearance of the“gas cushion”beneath the baffles,whose height increases with increasing superficial gas velocity.On the other hand,a region with stronger particle circulation induced by the inclined slat array was observed in the experiments.The slat near the wall and located below the region of downward-flowing particles was found to be subjected to the severest forces.Therefore,the slats located in similar locations of industrial baffles are suggested to be reinforced to increase their structural strength.