Expansive Behaviors of Self-stressing Concrete under Different Restraining Conditions

The expansive behaviors of the expensive concrete under different restraining conditions were systemically studied. The experimental results indicate that expansive deformation obviously increases before 10 days and tends to be constant after 25 days regardless of the restraining conditions. The mixture ratio of expansive cement and restraining conditions are the main factors affecting expansive deformation. Self-stress can be obtained when the expansive deformation is restrained. The higher self-stress could be obtained when the expensive concrete is restrained by steel tube. For specimens under steel tube restraining, the wall thickness and the length of the steel tube have important influence on self-stress. Both the radial self-stress and axial self-stress in concrete core increase when wall thickness or length of the steel tube increases.

A LOOP DRAWBEAD RESTRAINING FORCE MODEL IN SHEET METAL DEEP DRAWING PROCESS

In sheet metal forming, drawbeads are often used to control uneven material flow which may cause defects such as wrinkles, fracture, surface distortion and springback. Appropriate setting and adjusting the drawbead force is one of the most important pa- rameters in sheet metal forming process control. This paper derives the model of loop drawbead restraining force (DBRF) using plastic forming theory, and gives the min imum blankholding force. Experiments are carried out to verify the proposed DBRF model. The good agreement between the calculated values and experiments data justi- fies the proposed loop drawbead restraining force model.

EXPERIMENTAL TESTING OF DRAW-BEAD RESTRAINING FORCE IN SHEET METAL FORMING

Due to complexities of draw-bead restraining force calculated according to theory and depending on sheet metal forming properties experiment testing system, a simplified method to calculate draw-bead restraining force is put forward by experimental method in cup-shaped drawing process. The experimental results were compared with numerical results and proved agreement. It shows the method is effective.

Chemical composition and free radicals restraining activity of extracts from three Manglietia species leaves

The extracts from leaves of Manglietia insignis （Wall） Blume, Manglietia chingii Dandy and Manglietia yuyuanensis Law were prepared by organic solvent extraction and their components were analyzed by GC/MS and quantified. Meanwhile, the free radicals restraining activities were detected. The 21 compounds in M. insignis, 36 compounds in M. chigii and 20 compounds in M. yuyuanensis were identified. There were 11 common components in the extracts from three Manglietia species, and 12 components in two Manglietia species. The results of relative contents of every component in three extracts showed that the main constituents of M. insignis were terpenoids and alkene, amounting to 38.93%, followed by alkane （28.18%）, the nitrogen containing compounds （15.73%） and aromatic compounds （7.23 %）. The main constituents of leaf extract from M. chingii were the terpenoids and alkene, carboxylic acid, alkane and aromatic compounds, amounting to 30.22%, 14.17%, 13.87% and 13.29%, respectively, The main constituents of M. yuyuanensis were alcohol compounds, the terpenoids and alkene, and aromatic compounds, amounting to 28.00%, 25.38% and 18.00% respectively. The results showed that the three extracts had strong function of restraining oxygen free radicals. The ultra oxygen anions activity was restrained at the highest level, when the three extracts were diluted by hundred-fold, whereas the restraining capacity of hydroxyl free radicals reached maximum, when the three extracts were diluted by twenty-fold. The above results provide scientific evidences for further approaching the ecological healthy function of three MangUetia species

STUDY ON RESTRAINING THE RESIDUAL VIBRATION OF FLEXIBLE ARM BY PLANNING ACCELERATION

The method of planning acceleration is discussed to restrain the residual vibration of flexible arm. Based on the built mathematical model of the flexible arm, the equations of vibration with acceleration,vibration frequency,damping and time are obtained theoretically.According to the vibration frequency and damping, the suitable acceleration is executed experimentally to the flexible arm at the corresponding time. The result shows that this way can give rise to good effect to restrain the residual vibration.

Numerical Simulation and Assessment of Self-induced Tensile Stresses in Steel Ring Restrained Concrete

For a better understanding of the strains and stresses,numerical simulation was conducted by using ANSYS under the assumption of absolute bond between the steel and concrete.The results show that the stresses and strains in such concrete and steel rings are uneven;the curves of strains and stresses change gradually around the interface.To ease numerical computation,the mechanical system was simplified under the assumptions of synchronous deformation and uniform strains and stresses.The results of the numerical simulation and simplified stress calculation can match almost perfectly.It means that the simplified mechanical model can be used in stress and visco-elastic behavior quantification.

Restraining NO_x Formation during Coal Combustion in Packed Bed

The effects of various combustion conditions (i. e. particle size of coals, oxygen concentration in combustion gas and coal content in the fuel bed, etc.), on reducing conversion of NO_x during coal combustion were studied. Under the present combustion conditions, coals with smaller particle size gave the lower conversion of NO_x, and as expected that an decrease in overall stoichiometric ratio, whether by an decrease in O_2 content in combustion gas or by an increase in coal content in fuel bed would lead to a lower conversion of NO_x. In order to investigate the effect of metallic oxide layers on restraining NO_x formation, the combustion experiments for coal granules with adhering layer of various metallic oxides including Fe_2O_3, Ni_2O_3 and mixed oxides Fe-Ni-O_x were conducted in a packed bed combustor. The combustion experiments have shown that most of adhering materials gave considerable effect on reduction of NO_x emission during coal combustion.

Restraining Factors and Improving Paths for the Operation Mechanism of New Rural Cooperative Medical System in China

The new rural cooperative medical system has achieved periodical achievements since its establishment.Nevertheless,there are many factors hampering the development of the new system,such as the high cost,the difficulties in fund procurement,the lack of management,the narrow coverage of benefit,the ineffective constraint to the designated medical institutions,the high fund balance rate,and the poor medical facilities and services in rural areas.Countermeasures are put forward to solve these problems,including improving the system design,expanding the coverage of the system,expanding the fund sources,reducing the financing costs,strengthening the fund supervision,enhancing the supervision of designated medical institutions,and improving the capacity of health services in rural areas.

Rapid evolution of T2/S-RNase genes in Fragaria linked to multiple transitions from self-incompatibility to self-compatibility

The T2/RNase gene family is widespread in eukaryotes,and particular members of this family play critical roles in the gametophytic self-incompatibility(GSI) system in plants.Wild diploid strawberry(Fragaria)species have diversified their sexual systems via self-incompatible and self-compatible traits,yet how these traits evolved in Fragaria remains elusive.By integrating the published and de novo assembled genomes and the newly generated RNA-seq data,members of the RNase T2 gene family were systematically identified in six Fragaria species,including three self-incompatible species(Fragaria nipponica,Fragaria nubicola,and Fragaria viridis) and three self-compatible species(Fragaria nilgerrensis,Fragaria vesca,and Fragaria iinumae).In total,115 RNase T2 genes were identified in the six Fragaria genomes and can be classified into three classes(Ⅰ-Ⅲ) according to phylogenetic analysis.The identified RNase T2 genes could be divided into 22 homologous gene sets according to amino acid sequence similarity and phylogenetic and syntenic relationships.We found that extensive gene loss and pseudogenization coupled with small-scale duplications mainly accounted for variations in the RNase T2 gene numbers in Fragaria.Multiple copies of homologous genes were mainly generated from tandem and segmental duplication events.Furthermore,we newly identified five S-RNase genes in three self-incompatible Fragaria genomes,including two in F.nipponica,two in F.viridis,and one in F.nubicola,which fit for typical features of a pistil determinant,including highly pistil-specific expression,highly polymorphic proteins and alkaline isoelectric point(pI),while no S-RNase genes were found in all three selfcompatible Fragaria species.Surprisingly,these T2/S-RNase genes contain at least one large intron(>10 kb).This study revealed that the rapid evolution of T2/S-RNase genes within the Fragaria genus could be associated with its sexual mode,and repeated evolution of the self-compatible traits in Fragaria was convergent via losses of S-RNase.

Region coverage control for multiple stratospheric airships with combined self-/event-triggered mechanism

The region coverage control problem of multiple stratospheric airships system is firstly addressed in this paper.Towards it,we propose a two-layer control framework with the artificial potential field(APF)-based region coverage control law and the adaptive tracking control law.The APF-based region coverage control law ensures the coverage task is achieved until every single stratospheric airship ends up performing station keeping where near the respective global minimum point,in which an innovative solution to the local minimum problem is put forward.The adaptive tracking control law is designed to realize motion control using tracking the desired velocity and angular velocity given by coverage control law,with the consideration of several practical control problems as unknown individual differences and external disturbances.To save resources,the combined self-/event-triggered mechanism designed therein significantly reduces the times of state information transmission and control law calculation.The effectiveness of the proposed control framework is verified through simulations.

Macrophage fumarate hydratase restrains mtRNA-mediated interferon production

Metabolic rewiring underlies the effector functions of macrophages1-3,but the mechanisms involved remain incompletely defined.Here,using unbiased metabolomics and stable isotope-assisted tracing,we show that an inflammatory aspartate argininosuccinate shunt is induced following lipopolysaccharide stimulation.The shunt,supported by increased argininosuccinate synthase(ASS1)expression,also leads to increased cytosolic fumarate levels and fumarate-mediated protein succination.Pharmacological inhibition and genetic ablation of the tricarboxylic acid cycle enzyme fumarate hydratase(FH)further increases intracellular fumarate levels.

Analytical solutions for the restraint effect of isolation piles against tunneling-induced vertical ground displacements

This paper presents a simplified elastic continuum method for calculating the restraint effect of isolation piles on tunneling-induced vertical ground displacement,which can consider not only the relative sliding of the pile‒soil interface but also the pile rowesoil interaction.The proposed method is verified by comparisons with existing theoretical methods,including the boundary element method and the elastic foundation method.The results reveal the restraining mechanism of the isolation piles on vertical ground displacements due to tunneling,i.e.the positive and negative restraint effects exerted by the isolation piles jointly drive the ground vertical displacement along the depth direction from the original tunneling-induced nonlinear variation situation to a relatively uniform situation.The results also indicate that the stiffness of the pile‒soil interface,including the pile shaft‒surrounding soil interface and pile tip-supporting soil interface,describes the strength of the pile‒soil interaction.The pile rows can confine the vertical ground displacement caused by the tunnel excavation to the inner side of the isolation piles and effectively prevent the vertical ground displacement from expanding further toward the outer side of the isolation piles.

Effects of connection types and elevated temperature on the impact behaviour of restrained beam in portal steel frame

Based on the background of structural protection and Disaster Reduction Engineering, the dynamic behaviour and failure mechanism of restrained beams in portal steel frames in localised fire are investigated via experimental measurement and numerical simulation techniques. Comprehensive parametric studies are carried out to discuss the influence of end connection types, temperature, impact velocity,impact mass and span-to-depth ratio(SDR) on the dynamic response of the beams. The characteristics of deformation, internal force and energy distribution about the restrained beams and its joints are investigated. A temperature dependent criterion for evaluating the frame joint performance is proposed to measure the degree of performance degradation and impact resistance of the joint. The dynamic displacement amplification factor in different temperature environments are proposed for the different beam end constraint types and SDRs. Results of the experimental and numerical analysis show that the welded connection(WC) of three typical joint types is the strongest, and the extended endplate connection(EEC) is the weakest in terms of the impact resistance performance. With regard to the failure mode of the joint, the failure positions of the WC and the welded-bolted connection are located in the inner web of the column. Meanwhile, the EEC is located in the connection position between the beam and the endplate. Three different internal force stages and two obvious critical temperature boundaries of the restrained beams emerge with the increase in temperature, and they have significant characteristics in terms of deformation trend, internal force transfer and energy distribution. During the impact, a phenomenon known as “compression arch action” develops into “catenary action” with the increase in deflection in the frame beam mechanism.

基于“承制从势”思想探讨中医药治疗新型冠状病毒感染的中医机理

“承制从势”思想源于“亢害承制”理论,认为机体与生俱来的“承制自稳”功能是消除“亢害之乱”的决定性力量,医疗干预当遵循“从其势,助其力”原则。新型冠状病毒(新冠病毒)感染的本化病邪为具有湿毒属性的疫戾之气,多挟寒、热、燥、风等兼化病邪,治疗当“分期分型,辨证论治,宗法温病,承制从势”。直接助力宜扶正祛邪,顺从制势,旨在增强承制自稳功能并直接清除体内新冠病毒,主要治法为宣肺祛湿败毒;间接助力宜对症打援,截断病势,重视基础病治疗,意在为承制自稳功能清除体内新冠病毒创造良好生态环境,主要治法为健脾散寒通腑。痰瘀闭肺是由重转危、由闭转脱的关键病理机转,须在“承制从势”思想指导下,综合运用直接助力与间接助力的各种治疗方法。

考虑约束扭转二次剪力流影响的箱梁畸变效应分析

为了揭示箱梁约束扭转和畸变之间的耦联关系,研究约束扭转对箱梁畸变效应的影响,根据约束扭转二次剪力流形成的畸变荷载,建立了考虑约束扭转的箱梁畸变控制微分方程.基于乌曼斯基第二理论,提出约束扭转剪力流是基于约束扭转引起的畸变效应修正后的总扭矩布雷特剪力流,并通过Ansys有限元模型和能量法计算结果对理论公式进行了验证.数值算例结果表明:2种不同约束扭转剪力流分解方法计算所得结果完全一致;不同计算点处的约束扭转剪应力与Ansys有限元法计算结果吻合良好;扭转畸变翘曲总正应力、畸变翘曲正应力均与按能量法计算所得结果吻合良好,误差不超过10%.计入约束扭转二次剪应力的影响能够更准确地计算箱梁畸变效应.

积石山6.2级地震桥梁典型震害特征

调查了306省道、310国道以及川亭公路上位于地震烈度8度和7度区的桥梁。GS.N0028台站记录到的大河家镇加速度峰值超过900 cm/s~2,远超当地罕遇地震设防标准,但从调查的结果看,本次地震中,8度区的桥梁震害主要以轻微破坏为主,包括挡块破坏、主梁侧移和支座滑移,除了川亭公路上发现一桥梁的桥墩出现剪切裂缝外,其他桥梁未发现主体结构发生破坏。7度区的桥梁基本完好,橡胶支座中橡胶有变形无法恢复以及主梁位移导致挡块间距发生变化,但都不影响功能。混凝土挡块作为主梁防侧移装置,震害虽然表明其有效性,但缺乏快速恢复的特性,同时设置缓冲橡胶垫的挡块仍然发生了较严重的破坏,因此,以后需要进一步加强挡块的缓冲装置和考虑可快速恢复性能的研究。

附加消能子结构在抗震加固工程中的应用

介绍了消能子结构的研究现状,文中以某小学教学楼抗震加固工程为例,阐述了采用附加消能子结构配合屈曲约束支撑进行抗震加固的设计过程,采用阵型分解反应谱法和时程分析法分析并对比了加固前后结构的抗震性能变化,基于现有研究成果,进行了消能子结构的加固设计和罕遇地震作用下的承载力复核。结果表明:采用附加消能子结构对结构进行抗震加固,在提高建筑抗震性能的同时,可以不影响建筑内部功能。加固后,结构整体刚度增加,自振周期变短,层间剪力增大,整体变形变小,结构的整体受力状态和变形模式得到改善,房屋整体抗震性能提升。罕遇地震作用下,结构整体塑性程度较低,损伤屈服机制更加合理,可以实现“大震不倒”的设防目标。消能子结构为连接消能器和主体结构的关键构件,应重点进行设计,采用柱的N-M曲线进行承载力复核比较便捷。文中设计思路可为类似工程提供借鉴和参考。

火灾下LYP160屈曲约束支撑抗震性能研究

为研究屈曲约束支撑(buckling-restrained brace,BRB)及其体系在高温工况的抗震性能,对BRB芯材低屈服点LYP160钢材分别进行了常温和高温材料力学性能试验.通过与试验结果比较,建立了BRB热-力耦合精细化有限元分析模型,验证了该模型的准确性;对火灾下LYP160屈曲约束支撑的温度场、滞回曲线、骨架曲线和耗能能力等性能进行了对比分析;对不同工况(3种火灾工况和常温工况)下8层配置屈曲约束支撑钢框架(BRB structure,BS)和原结构(original structure,OS)分别进行了弹塑性动力时程分析.研究结果表明:3种火灾工况下BS的平均层间位移角较于OS分别降低了30.4%、33.2%和42%;OS柱塑性铰损坏严重,且更多出现在柱上,BS整体损坏程度较OS轻,更为安全可靠.

模块化防屈曲钢板墙抗震性能

考虑经济性和便利性,提出了模块化防屈曲钢板墙及其常用模数,然后基于已有的防屈曲钢板墙的简化计算模型,推导了在不同墙数量情况下,模块化防屈曲钢板墙充分发挥抗震性能时,周边梁的承载力和刚度需求,并提出了周边梁的设计方法.进而,对模块化防屈曲钢板墙和整体墙进行了对比验证试验及其有限元模拟分析.研究结果表明:模块化防屈曲钢板墙能够达到与整体钢板墙相同的抗震性能,且周边梁未发生明显转动和破坏,说明所提出的周边梁设计方法是合理的;在层间位移角为1/50时,防屈曲钢板墙上下周边梁均未进入塑性,且承载力和初始刚度等的有限元值与试验值误差小于6%,从而进一步验证了其抗震性能.