Self-centering seismic retrofit scheme for reinforced concrete frame structures:SDOF system study

This paper presents the results of a parametric study of self-centering seismic retrofit schemes for reinforced concrete (RC) frame buildings. The self-centering retrofit system features flag-shaped hysteresis and minimal residual deformation. For comparison purpose,an alternate seismic retrofit scheme that uses a bilinear-hysteresis retrofit system such as buckling-restrained braces (BRB) is also considered in this paper. The parametric study was carried out in a single-degree-of-freedom (SDOF) system framework since a multi-story building structure may be idealized as an equivalent SDOF system and investigation of the performance of this equivalent SDOF system can provide insight into the seismic response of the multi-story building. A peak-oriented hysteresis model which can consider the strength and stiffness degradation is used to describe the hysteretic behavior of RC structures. The parametric study involves two key parameters -the strength ratio and elastic stiffness ratio between the seismic retrofit system and the original RC frame. An ensemble of 172 earthquake ground motion records scaled to the design basis earthquake in California with a probability of exceedance of 10% in 50 years was constructed for the simulation-based parametric study. The effectiveness of the two seismic retrofit schemes considered in this study is evaluated in terms of peak displacement ratio,peak acceleration ratio,energy dissipation demand ratio and residual displacement ratio between the SDOF systems with and without retrofit. It is found from this parametric study that RC structures retrofitted with the self-centering retrofit scheme (SCRS) can achieve a seismic performance level comparable to the bilinear-hysteresis retrofit scheme (BHRS) in terms of peak displacement and energy dissipation demand ratio while having negligible residual displacement after earthquake.

Structure and Properties of Self-reinforced Material Made from Ultra-high Molecular Weight Polyethylene-montmorillonite Nanocomposite

High-strength and high-modulus ultra-high molecular weight polyethylene(UHMWPE), named self-reinforced material, was obtained by the elongation of UHMWPE-montmorillonite nanocomposite at melting temperature. According to the scanning electron microscope(SEM) analysis, a great deal of fibrillar texture formed in the direction of elongation, and the tensile fractured surface was similar to that of highly oriented fiber. The transmission electron microscope(TEM) and selective area electron diffraction(SAED) analyses reveal that the reinforced phase of the self-reinforced material is an extended chain crystal and its size is about 50_200 nm wide and several microns long, and the montmorillonite layers are broken up to pieces in the size from 100 to 10 nm. The broken layers which have a huge surface area interacting strongly with macromolecules reduces the entanglement density of UHMWPE and induces the chain orientation in flow field. It is supposed that the astriction of montmorillonite layers to polyethylene chains is not only end-tethered but also side-tethered. The differential scan calorimetry(DSC) analysis shows that there are two endothermal peaks for the self-reinforced material, of which the peak at a higher temperature(136.4 ℃) is ascribed to the melting of the reinforced phase.

Experimental Studies of Self Healing Behaviour of Under-Aged Al-Mg-Si Alloys and 60Sn-40Pb Alloy Reinforced Aluminium Metal-Metal Composites

Experimental studies to demonstrate self healing potentials of Al-Mg-Si alloy were undertaken in this research work. Self healing exploring secondary precipitation in the Al-Mg-Si alloy and use of low melting metallic alloy reinforcement (60Sn-40Pb alloy) were used as basis for the investigation. For the precipitation study, the Al-Mg-Si alloy was under-aged at temperature of 160oC for 10 minutes and then subjected to second step ageing treatment at four different temperatures within the range of 25oC and 70oC. In the 60Sn-40Pb alloy reinforced Al-Mg-Si alloy study, the samples were prepared in pre-cracked state and then subjected to healing heat-treatment at 250oC. For all cases tensile test and healing efficiency was used to analyze the results generated. It was observed that a second step thermal ageing at 50oC resulted in peak improvement in tensile strength, yield strength, toughness and percent elongation while ageing above this temperature lead to a drop in the tensile properties in comparison to that of the sample not subjected to a second ageing treatment. Also the use of 60Sn-40Pb alloy as reinforcement in the Al-Mg-Si alloy resulted in a healing efficiency of 91% after pre-cracking and heat-treatment. The satisfactory bonding between the 60Sn-40Pb alloy and the Al-Mg-Si alloy matrix contributed to the high healing efficiency observed.

Fatigue tests of composite beam by steel fiber reinforced self-stressing concrete in the hogging bending

Through the experiments of 7 T-section composite beams, steel fiber reinforced self-stressing concrete （SFRSC） as the composite beam in the composite layer was studied under the hogging bending. The tests simulated composite layer tensile strain under the hogging bending of inverted loading composite beams, giving the relationship under the different fatigue stress ratios between fatigue cycles and steel bar’s stress range, crack width, stiffness loss and damage, etc., in composite layer. This article established fatigue life equation, and analyzed SFRSC reinforced mechanism to crack width and stiffness loss. The results show that SFRSC as the composite beam concrete has excellent properties of crack resistance and tensile, can reinforce the fatigue crack width and stiffness loss of composite beams, and improve the durability and in normal use of composite beams in the hogging bending zone.

Manufacturing of Ultra-high Molecular Weight Polyethylene Fiber Reinforced Tape and the Loss of Strength

Due to the low density and excellent mechanical proper-ties,high performance fiber reinforced materials have aconsiderable application in the area of high technologyand dally usage.In this paper,the Ultra-high Molecu-lar Weight Polyethylene(UHMWPE)fiber reinforcedPE tape prepared with the method of powder impregnat-ion was studied.The effect of impregnate length and thetensile force of the yarn on the fiber content as well as on the strength and modulus of the tape were discussed.Calculation shows that the strength and the modulus ofthe ULMWPE fiber can keep about 85％ after it undergothe process.

Self-learning Fuzzy Controllers Based On a Real-time Reinforcement Genetic Algorithm

This paper presents a novel method for constructing fuzzy controllers based on a real time reinforcement genetic algorithm. This methodology introduces the real-time learning capability of neural networks into globally searching process of genetic algorithm, aiming to enhance the convergence rate and real-time learning ability of genetic algorithm, which is then used to construct fuzzy controllers for complex dynamic systems without any knowledge about system dynamics and prior control experience. The cart-pole system is employed as a test bed to demonstrate the effectiveness of the proposed control scheme, and the robustness of the acquired fuzzy controller with comparable result.

Effect of Point Source, Self-Reinforcement and Heterogeneity on the Propagation of Magnetoelastic Shear Wave

This paper investigates the propagation of horizontally polarised shear waves due to a point source in a magnetoelastic self-reinforced layer lying over a heterogeneous self-reinforced half-space. The heterogeneity is caused by consideration of quadratic variation in rigidity. The methodology employed combines an efficient derivation for Green’s functions based on algebraic transformations with the perturbation approach. Dispersion equation has been obtained in the closed form. The dispersion curves are compared for different values of magnetoelastic coupling parameters and inhomogeneity parameters. Also, the comparative study is being made through graphs to find the effect of reinforcement over the reinforced-free case on the phase velocity. It is observed that the dispersion equation is in assertion with the classical Love-type wave equation in the absence of reinforcement, magnetic field and heterogeneity. Moreover, some important peculiarities have been observed in graphs.

主余震作用下摇摆-自复位桥墩抗震性能分析

为探究摇摆-自复位(rocking self-centering,RSC)桥墩在主余震作用下的抗震性能,基于OpenSees建立RSC桥墩与普通现浇钢筋混凝土桥墩抗震数值分析模型,对比分析了两种桥墩分别在主震和主余震作用下的墩底弯矩-曲率、最大墩顶位移和残余位移,并采用增量动力分析法和Park-Ang损伤指标评估了其损伤状态。结果表明:在0.6 g主余震作用下,RSC桥墩的墩底截面最大曲率为普通现浇钢筋混凝土桥墩的2.84%~10.04%,墩底截面最大弯矩随着耗能钢筋配筋率的增大而减小;当地震强度为0.4~0.6 g时,余震会使RSC桥墩的最大墩顶位移增大1.65%~8.36%;余震对RSC桥墩残余位移的影响不明显;在主震过后处于中等损伤或严重损伤的RSC桥墩,需要考虑余震对其的附加损伤,当地震强度大于0.5 g时,余震对RSC桥墩的损伤增量会随着耗能钢筋配筋率增大而增大。

Preparation of a High-Performance Si_3N_4 Ceramic Using Self-Reinforcing Technology

The self-reinforced Si_3N_4 ceramics which contain Y_2O_3 and La_2O_3 additives have been prepared by hot-pressing. Under the optimum processing conditions, this material has the flexural strength of 960～1050MPa and the fracture toughness of 11.17～12.74MPa·m^(1/2) at room-temperature, and 720～780MPa and 22～24MPa·m^(1/2) at 1350℃. The effects of heat ing rate, sintering temperature, and holding time on the microstructures and mechanical properties are investigated. The experimental results show that an appropriate β-Si_3N_4 grain size and homogeneous microstructure can be obtained under the conditions of a heating rate of 10℃/min, sintering temperature of 1800℃, and holding time of 1h, which are advantageous to enhancing the mechanical properties. Crack deflection in large rodlike β-Si_3N_4 grains is a principle source of toughening.

Effects of characteristic inhomogeneity of bamboo culm nodes on mechanical properties of bamboo fiber reinforced composite

Dendrocalamus farinosus and Phyllostachys heterocycla bamboo logs were subjected to a novel treat- ment process for the preparation of bamboo fiber mats （BFMs）, and the obtained BFM were used to fabricate bamboo fiber reinforced composite （BFRC）. We studied the mechanical properties of the BFRCs manufactured from the mats with and without bamboo nodes. The pres- ence of nodes in BFM greatly reduced tensile strength, compressive strength, modulus of elasticity, and modulus of rupture of the BFRCs, while the BFRCs fabricated from BFMs with nodes possessed higher horizontal shear strength. Therefore, the nodes in bamboo culms were an important factor in the uniform distribution of mechanical properties, and BFMs should be homogeneously arranged to reduce the impact of nodes on the mechanical strengths of BFRCs.

Parameter Self - Learning of Generalized Predictive Control Using BP Neural Network

This paper describes the self—adjustment of some tuning-knobs of the generalized predictive controller(GPC).A three feedforward neural network was utilized to on line learn two key tuning-knobs of GPC,and BP algorithm was used for the training of the linking-weights of the neural network.Hence it gets rid of the difficulty of choosing these tuning-knobs manually and provides easier condition for the wide applications of GPC on industrial plants.Simulation results illustrated the effectiveness of the method.

Self - Crosslinking Behavior of Self - Emulsion Water - Based Polyure-thane Coating Agents

The relation between structures and properties of polyurethane are investigated by modern physical and chemical methods.The results obtained are as follows:the effects of the content of self-crosslinking agent on the properties of polyurethane,i.e.,dispersion stability,dynamical viscoelasticity and mechanical properties are discussed.It is found that the optimum molar ratio of epichlorohydrin and diethylenetriamine is 1:2.A mois-

Culture Self- Consciousness in Transmission of Chinese Philosophy from the Perspective of English Globalization -- Taking the Belt and Road Initiative for Example

The Belt and Road Initiative contains the aspiration of Chinese nation to pursue ideological freedom and desire of strengthening international exchanges and cooperation. This paper takes the Belt and Road Initiative for example,emphasizing the interpretation of the inheritance and development of Chinese culture so as to study the importance of Culture Self-Consciousness in Chinese Philosophy,in the context of English globalization. That is to say,this paper stresses the spirits and the stand of nation 's demonstration on pursuing peace,cooperation and sustainable development in the civilization continuity from traditional China to the contemporary China,with practical philosophic view.

合作-竞争混合型多智能体系统的虚拟遗憾优势自博弈方法

合作-竞争混合型多智能体系统由受控的目标智能体和不受控的外部智能体组成.目标智能体之间互相合作,同外部智能体展开竞争,应对环境和外部智能体的动态变化,最终完成指定的任务.针对如何训练目标智能体使他们获得完成任务的最优策略的问题,现有工作从两个方面展开:(1)仅关注目标智能体间的合作,将外部智能体视为环境的一部分,利用多智能体强化学习来训练目标智能体.这种方法难以应对外部智能体策略未知或者动态改变的情况;(2)仅关注目标智能体和外部智能体间的竞争,将竞争建模为双人博弈,采用自博弈的方法训练目标智能体.这种方法主要针对单个目标智能体和单个外部智能体的情况,难以扩展到由多个目标智能体和多个外部智能体组成的系统中.结合这两类研究,提出一种基于虚拟遗憾优势的自博弈方法.具体地,首先以虚拟遗憾最小化和虚拟多智能体策略梯度为基础,设计虚拟遗憾优势策略梯度方法,使目标智能体能更准确地更新策略;然后,引入模仿学习,以外部智能体的历史决策轨迹作为示教数据,模仿外部智能体的策略,显式地建模外部智能体的行为,来应对自博弈过程中外部智能体策略的动态变化;最后,以虚拟遗憾优势策略梯度和外部智能体行为建模为基础,设计一种自博弈训练方法,该方法能够在外部智能体策略未知或者动态变化的情况下,为多个目标智能体训练出最优的联合策略.以协同电磁对抗为研究案例,设计具有合作-竞争混合特征的3个典型任务.实验结果表明,同其他方法相比,所提方法在自博弈效果方面有至少78%的提升.

Surface wave transference in a piezoelectric cylinder coated with reinforced material

The present study deals with the propagation of a polarized shear horizontal(SH)wave in a pre-stressed piezoelectric cylinder circumscribed by a self-reinforced cylinder.The interface of the two media is assumed mechanically imperfect.For obtaining the dispersion relation,the mathematical formulation has been developed and solved by an analytical treatment.The effects of various parameters,i.e.,the thickness ratio,the imperfect interface,the initial stress,the reinforcement,and the piezoelectric and dielectric constants,on the dispersion curve are observed prominently.The dispersion curves for different modes have been also plotted.The consequences of the study may be used for achieving optimum efficiency of acoustic wave devices.

基于状态-动作联合掩码的自监督学习算法

视觉强化学习以原始图像作为输入,面临着观测空间维度高、冗余信息多、采样效率低等挑战。现有研究大多通过构建一个自监督辅助任务来获取高维观测中的有效表征,然而这类方法仅关注状态特征,却忽略了动作空间中丰富的语义信息。针对这一问题,提出一种基于状态-动作联合掩码的自监督学习算法,通过对状态和动作进行联合掩码重构,从而学习到真正与任务相关的表征信息,提高采样效率。此外,为提高模型的鲁棒性,引入测试时自适应方法,在环境变化时冻结强化学习策略网络,仅对状态-动作联合掩码模块进行少量更新,利用自监督信号帮助智能体快速适应新环境。实验结果表明,该方法相比现有算法,在DMControl环境上的平均回报奖励提升了4.5%,在DMControl-GB环境上的平均回报奖励提升了20.2%,有效提升了模型的性能。

Self-Play and Using an Expert to Learn to Play Backgammon with Temporal Difference Learning

A promising approach to learn to play board games is to use reinforcement learning algorithms that can learn a game position evaluation function. In this paper we examine and compare three different methods for generating training games: 1) Learning by self-play, 2) Learning by playing against an expert program, and 3) Learning from viewing ex-perts play against each other. Although the third possibility generates high-quality games from the start compared to initial random games generated by self-play, the drawback is that the learning program is never allowed to test moves which it prefers. Since our expert program uses a similar evaluation function as the learning program, we also examine whether it is helpful to learn directly from the board evaluations given by the expert. We compared these methods using temporal difference methods with neural networks to learn the game of backgammon.

基于PET-CNT自感应复合纤网插层的玻璃纤维增强复合材料层间增韧-结构监测一体化响应

为了避免玻璃纤维增强复合材料(GFRC)在服役过程中由于局部分层损伤造成灾难性整体失效,采用高孔隙率、薄型聚对苯二甲酸乙二醇酯(PET)非织造纤网构筑PET-碳纳米管(CNT)自感应复合纤网插层,再将插层嵌入玻纤增强体层间一体成型,在改善GFRC层间性能的同时,对其结构健康状态进行原位、实时、在线的无损监测。结果表明:PET-CNT复合纤网改性GFRC的起始断裂韧性和扩展断裂韧性分别提高了86%和48%,有效提升了GFRC的I型层间断裂韧性。另外,在裂纹扩展阶段,PET-CNT复合纤网插层的电阻变化率增益因子高达270%,表现出了极高的层间裂纹监测敏感性。研究结果为提升GFRC力学性能并实现结构健康监测提供了一种集成结构增韧-监测功能一体化的新型非织造复合纤网插层,也为提升GFRC全寿命周期稳健性提供了一种结构优化方法。

基于风险感知的认知-态度-行为强化策略在2型糖尿病病人中的应用

目的:基于风险感知的认知-态度-行为强化策略在2型糖尿病病人中的应用效果。方法:选取2022年1月—2023年1月通州区社区建档在管的104例2型糖尿病病人为研究对象,采用抽签法将其分为试验组和对照组各52例。对照组给予常规风险感知教育,试验组为病人实施基于风险感知的认知-态度-行为强化策略,观察并比较两组病人自我管理知识、态度及行为、血糖控制情况及生活质量情况。结果:干预后试验组病人自我管理知识、态度、行为各维度评分高于对照组,空腹血糖、餐后2 h血糖、糖化血红蛋白及生活质量评分均明显低于对照组(P<0.05)。结论:基于风险感知的认知-态度-行为强化策略对改善2型糖尿病病人自我管理知识、态度、行为水平,控制血糖水平,提高生活质量均具有积极意义。

过程性评价-强化巩固健康宣教模式对白血病化疗患者的影响

目的 探究基于过程性评价-强化巩固的健康宣教模式对白血病化疗患者应对方式、自护效能、心理状态等方面的影响,以期为白血病化疗患者预后及其治疗方案的优化提供参考。方法 选取2020年6月至2022年6月于四川大学华西医院血液内科就诊的102例白血病化疗患者作为研究对象,按照随机数字表法分为对照组和观察组,每组51例。对照组采用传统宣教模式进行干预,观察组采用过程性评价-强化巩固的健康宣教模式进行干预。比较干预前、干预3个月后两组患者应对方式[特质应对方式问卷(TCSQ)]、自我效能[一般自我效能感量表(GSES)]、自护能力[自护能力测量表(ESCA)]、心理状态[心理弹性量表(CD-RIS)]以及生活质量(白血病临床结局表)的变化。结果 干预3个月后,两组患者TCSQ积极应对评分,GSES评分,ESCA评分中自我概念、自护责任感、知识水平、自护技能4个维度,CD-RIS中坚韧性、力量性、乐观性3项评分,白血病临床结局表中生理、心理、社会、治疗4个维度评分均高于干预前评分(P<0.05),且观察组高于对照组(P<0.05);干预3个月后,两组患者TCSQ消极应对评分低于干预前评分(P<0.05),且观察组低于对照组(P<0.05)。结论 基于过程性评价-强化巩固的健康宣教模式在促进白血病化疗患者积极应对疾病,提升患者自护能力和自我效能方面具有一定效果。