被困空腔对T-bar循环贯入软黏土流动特性影响的试验研究

为观测和分析T-bar循环贯入过程中被困空腔对软黏土流动特性的影响,利用Laponite RD、焦磷酸钠和去离子水配制透明黏土,自制由加载设备、CCD相机、激光器和控制系统组成的T-bar循环贯入试验装置,开展T-bar在透明黏土中的循环贯入试验。结果表明:T-bar初次贯入过程中,被困空腔影响土体绕探头的流动,土体不能进入全流动状态;T-bar初次上拔过程中,被困空腔与探头发生脱离,悬浮于探头上方,对土体流动的影响逐渐减弱,T-bar上拔2倍探头直径深度时土体流动不再受被困空腔影响,进入到全流动状态;第2—第10次循环贯入过程中,被困空腔稳定悬浮于土中,不影响土体流动,T-bar贯入1倍探头直径深度时土体流动表现为全流动状态;被困空腔对于T-bar循环贯入测试结果无显著影响,在T-bar初次贯入被困空腔阶段下通过T-bar循环贯入测试软黏土重塑强度是合理的。

Reliability-Based Topology Optimization of Fail-Safe Structures Using Moving Morphable Bars

This paper proposes an effective reliability design optimizationmethod for fail-safe topology optimization(FSTO)considering uncertainty based on the moving morphable bars method to establish the ideal balance between cost and robustness,reliability and structural safety.To this end,a performancemeasure approach(PMA)-based doubleloop optimization algorithmis developed tominimize the relative volume percentage while achieving the reliability criterion.To ensure the compliance value of the worst failure case can better approximate the quantified design requirement,a p-norm constraint approach with correction parameter is introduced.Finally,the significance of accounting for uncertainty in the fail-safe design is illustrated by contrasting the findings of the proposed reliabilitybased topology optimization(RBTO)method with those of the deterministic design method in three typical examples.Monte Carlo simulation shows that the relative error of the reliability index of the optimized structure does not exceed 3%.

神经肌肉电刺激辅以Flexi-bar运动训练治疗产后腹直肌分离的疗效观察

目的观察神经肌肉电刺激(NMES)辅以Flexi-bar运动训练治疗产后腹直肌分离(DRA)的疗效。方法选取产后DRA患者120例,随机分为观察组和对照组,每组60例。对照组患者接受NMES治疗,观察组患者接受NMES治疗联合Flexi-bar运动训练。连续治疗6周后,比较2组疗效差异。结果治疗前,2组患者脐上及脐下4 cm、平脐处腹直肌间距相比差异均无统计学意义(P>0.05);治疗后,2组患者脐上及脐下4 cm、平脐腹直肌间距均较治疗前降低,且观察组治疗后脐上4 cm、平脐及脐下4 cm腹直肌间距均小于对照组患者,差异有统计学意义(P<0.05)。治疗前,2组患者上腹围、中腹围、下腹围、腹直肌最大自主等长收缩振幅均方根(RMS)、盆底Ⅰ类肌纤维肌力最大值、盆底Ⅱ类肌纤维肌力平均值、SF-36各维度评分差异均无统计学意义(P>0.05);治疗后,2组患者上腹围、中腹围、下腹围均较治疗前降低,且观察组低于对照组,2组患者腹直肌最大自主等长收缩振幅RMS、盆底Ⅰ类肌纤维肌力最大值、盆底Ⅱ类肌纤维肌力平均值、SF-36各维度评分均较治疗前升高,且观察组高于对照组,差异有统计学意义(P<0.05)。结论NMES辅以Flexi-bar运动训练治疗产后DRA的效果显著,有助于增强患者腹部肌肉力量,提高患者生活质量。

表达barstar基因及bar基因的转基因油菜的研究

从细菌Ｂａｃｉｌｕｓａｍｙｌｏｌｉｑｕｅｆａｃｉｅｎｓ染色体ＤＮＡ中克隆了ｂａｒｎａｓｅ抑制剂ｂａｒｓｔａｒ的基因，构建了带有ＴＡ－２９基因５′调控区（－１３００－＋３）与ｂａｒｓｔａｒ基因编码区、ＣａＭＶ３５Ｓ启动子与除草剂抗性基因ｂａｒ两个表达框架的植物表达质粒ｐＢＢＳ。以“双低”油菜“５－４”的子叶柄为受体，通过农杆菌介导的遗传转化，获得了在含有１０ｍｇ／Ｌ卡那霉素和２０ｍｇ／ＬＰＰＴ的筛选培养基上再生的转基因植株。ＰＣＲ分析结果表明，ｂａｒｓｔａｒ基因已整合到油菜染色体上；Ｎｏｒｔｈｅｒｎｂｌｏｔ检测表明，ｂａｒｓｔａｒ基因及ｂａｒ基因在转基因植物中得到了正确的调控与表达。以转基因油菜“５－４”为父本授粉给表达ｂａｒｎａｓｅ基因的雄性不育植株，不育株能正常结实。

基于BARS法的高校学生党员考核方法探究

深入有效地开展大学生党员考核工作是增强学生党员教育管理,构建发挥党员先锋模范作用长效机制的重要举措。在当前的学生党员考核中,评价量表法是广为采用的一种考核工具。作为一种数量化考核,该法使用方便,操作简单,测评面广。但也存在着主观随意性大,晕轮效应概率高,测评针对性低。

基于BARS的高校教务人员绩效考核研究

高等院校教学质量的提高,不单只是以高素质教师队伍为前提和保证,高效的教务管理也是教学质量的有效保障之一.针对现有高校教务人员绩效考核的不足,提出了基于BARS(行为锚定等级量表法)的有限360度绩效考核以完善教务人员的绩效考核,进而打造高效的教务管理.

深层肌肉刺激结合Flexi-bar疗法对非特异性下腰痛患者腰肌耐力疼痛及预后的影响

目的:探讨深层肌肉刺激结合Flexi-bar疗法对非特异性下腰痛(NLBP)患者腰肌耐力、疼痛及预后的影响。方法:选取2019年6月至2021年6月我院100例NLBP患者,随机数字表法分组,各50例。对照组采取常规康复训练,观察组基于对照组采取Flexi-bar疗法结合深层肌肉刺激,连续干预2个月。统计比较两组视觉模拟评分法(VAS)、Oswestry功能障碍指数(ODI)、静态及动态腰肌耐力、腰部肌电信号、疼痛介质[β-内啡肽(β-EP)、5-羟色胺(5-HT)]、预后。结果:干预1个月后、2个月后观察组VAS、ODI评分低于对照组,血清β-EP、5-HT水平高于对照组,差异有统计学意义(P<0.05);干预1个月后、2个月后观察组腰肌耐力、RMS高于对照组,MF低于对照组,差异有统计学意义(P<0.05);干预前、干预1个月后、2个月后两组SF-36评分比较,差异无统计学意义(P>0.05)。结论:深层肌肉刺激结合Flexi-bar疗法可有效减轻NLBP患者疼痛,提高腰肌耐力,恢复腰椎功能,改善预后。

Bragg Reflection of Waves by Different Shapes of Artificial Bars

Experiments are performed in a wave flume to demonstrate the Bragg reflection of linear gravity waves by artificial bars. Three different artificial bars with rectangular, triangular and rectified cosinoidal shapes are placed discretely on the seabed for measurement of the Bragg reflection. A series of experimental conditions including the number of bars, the periodic bar spacing, the water depth and various wave conditions are tested. Key parameters influencing the Bragg resonances are investigated. The experimental data are compared with the values from both theoretical and numerical models. Some key parameters have proved to be effective in describing the primary resonances. Predictive equations of the characteristics for the Bragg reflection are proposed in this paper.

Numerical Simulation of Wave Field near Submerged Bars by PLIC-VOF Model

Investigating the wave field near structures in coastal and offshore engineering is of increasing significance. In the present study, simulation is done of the wave profile and flow field for waves propagating over submerged bars, using PLIC-VOF （Pieeewise Linear Interface Construction） to trace the free surface of wave and finite difference method to solve vertical 2D Navier-Stokes （N-S） equations. A comparison of the numerical results for two kinds of submerged bars with the experimental ones shows that the PLIC-VOF model used in this study is effective and can compute the wave field precisely.

Effect of Freeze-thaw Cycles on Bond Strength between Steel Bars and Concrete

The effect of freezing and thawing cycles on mechanical properties of concrete （compressive, splitting tensile strength） was experimentally investigated. According to the pullout test data of three kinds of deformed steel bars, the bond stress-slip curves after freezing and thawing were obtained. The empirical equations of peak bond strength were proposed that the damage accounted for effects of freezing and thawing cycle. Meanwhile, the mechanism of bond deterioration between steel bars and concrete after freezing and thawing cycles was discussed. All these conclusions will be useful to the durability design and reliability calculation of RC structures in cold region.

Modeling and cyclic behavior of segmental bridge column connected with shape memory alloy bars

This paper examines the quasi-static cyclic behavior, lateral strength and equivalent damping capacities of a system of post-tensioned segmental bridge columns tied with large diameter martensitic Shape Memory Alloy （SMA） link-bars. Moment-curvature constitutive relationships are formulated and analysis tools are developed for the PT column, including a modified four-spring model prepared for the SMA bars. The suggested system is exemplified using a column with an aspect ratio of 7.5 and twelve 36.5 mm diameter NiTi martensitic SMA bars. A post-tensioning force of 40% to 60% of the tendon yield strength is applied in order to obtain a self re-centering system, considering the residual stress of the martensitie SMA bars. The cyclic response results show that the lateral strength remains consistently around 10% of the total vertical load and the equivalent viscous damping ratios reach 10%-12% of critical. When large diameter NiTi superelastic SMA bars are incorporated into the column system, the cyclic response varies substantially. The creep behavior of the superelastic SMA bar is accounted for since it affects the re-centering capability of the column. Two examples are presented to emphasize the modeling sensitivities for these special bars and quantify their cyclic behavior effects within the column assembly.

Tensile Strength Characteristics of GFRP Bars in Concrete Beams with Work Cracks under Sustained Loading and Severe Environments

To investigate the effect of different environmental conditions of GFRP bars in concrete beams with work cracks subjected to sustained loads, the beams were exposed in indoor, freeze/thaw cycles and immersed in alkaline solution at elevated temperature. The bars were carefully extracted from the beams and tested in order to evaluate residual tensile properties. The results show that the tensile strength decreased significantly in the highly aggressive conditions but not in the natural conditions. The effect of GFRP bars casting in concrete beams demonstrated approximately 2.5% decrease of tensile strength caused by pore water environment in concrete beams on basis of those of the original bars. The effect of sustained loading plus work cracks demonstrated about 10.5% tensile strength decrease on basis of those of the bars only casted in concrete beams. The effect of environments under sustained loading plus work cracks demonstrated about 17% tensile strength decrease caused by a saturated solution of Ca（OH）2 and 60-2 ℃ tap water （pH=12-13） and about 8% tensile strength decrease caused by freezing and thawing cycle （F/T）, both on basis of those of the bars of the indoor beams only under sustained loading plus work cracks. The results demonstrate the effects of the tensile strengths under different environmental conditions of GFRP bars in concrete beams with work cracks subjected to sustained loads.

Effect of austempering parameters on microstructure and mechanical properties of horizontal continuous casting ductile iron dense bars

In the present research, the orthogonal experiment was carried out to investigate the influence of different austempering process parameters(i.e. austenitizing temperature and time, and austempering temperature and time) on microstructure and mechanical properties of LZQT500-7 ductile iron dense bars with 172 mm in diameter which were produced by horizontal continuous casting(HCC). The results show that the major factors influencing the hardness of austempered ductile iron(ADI) are austenitizing temperature and austempering temperature. The fraction of retained austenite increases as the austenitizing and austempering temperatures increase. When austenitizing temperature is low, acicular ferrite and retained austenite can be effi ciently obtained by appropriately extending the austenitizing time. The proper austmepering time could ensure enough stability of retained austenite and prevent high carbon austenite decomposition. The optimal mechanical properties of ADI can be achieved with the following process parameters: austenitizing temperature and time are 866 °C and 135 min, and austempering temperature and time are 279 °C and 135 min, respectively. The microstructure of ADI under the optimal austempering process consists of fi ne acicular ferrite and a small amount of retained austenite, and the hardness, tensile strength, yield strength, elongation and impact toughness of the bars are HBW 476, 1670 MPa, 1428 MPa, 2.93% and 25.7 J, respectively.

Wave decomposition phenomenon and spectrum evolution over submerged bars

Wave decomposition phenomenon and spectrum evolution over submerged bars are investigated by a previously developed numerical model. First, the computed free surface displacements of regular waves at various locations are compared with the available experimental data to confirm the validity of the numerical model, and satisfactory agreements are obtained. In addition, variations of decomposition characteristics with incident wave parameters and the change of energy spectrum for regular waves are also studied. Then the spectrum evolution of irregular waves over submerged bars, as well as the influence of incident peak wave period and the steepness of the front slope of the bar on spectrum evolution, is investigated. Wave decomposition and spectral shape are found to be significantly influenced by the incident wave conditions. When the upslope of the bar becomes 1：2, the length of the slope becomes shorter and will not benefit the generation of high frequency energy, so spectrum evolution is not significant.

Blast resistance evaluation of urban utility tunnel reinforced with BFRP bars

To improve corrosion-resistance of shallow-buried concrete urban utility tunnels(UUTs),basalt fiber reinforced polymer(BFRP)bars are applied to reinforce UUTs.As the UUT must have excellent survival capability under accidental explosions,a shallow-buried BFRP bars reinforced UUT(BBRU)was designed and constructed.Repetitive blast experiments were carried out on this BBRU.Dynamic responses,damage evolutions and failure styles of the BBRU under repetitive explosions were revealed.The tunnel roof is the most vulnerable component and longitudinal cracks develop along the tunnel.When the scaled distance is larger than 1.10 m/kg1/3,no cracks are observed in the experiments.When the BBRU is severely damaged,there are five cracks forming and developing along the roof.The roof is simplified as a clamped-supported one-way slab,proved by the observation that the maximum strain of the transverse bar is much larger than that of the longitudinal bar.Dynamic responses of the roof slab are predicted by dynamic Euler beam theory,which can consistently predict the roof displacement under large-scaleddistance explosion.Compared with the UUT reinforced with steel bars,the BBRU has advantages in blast resistance with smaller deflections and more evenly-distributed cracks when the scaled distance is smaller than 1.260 m/kg1/3 and the steel bars enter plastic state.Longer elastic defamation of the BFRP bars endows the UUT more excellent blast resistance under small-scaled-distance explosions.

基于引文出版年光谱和波束图的学者学术评价与生涯分析——以Judit Bar-Ilan为例

为科学评价某一学者学术生涯特征,了解其学术研究传承脉络,并客观评价其学术影响,运用引文出版年光谱分析和波束图(Beamplot)方法,以WOS和Scopus数据库为数据基础,构建了学者个人学术发展和影响力评价体系。同时选择普赖斯奖获得者Judit Bar-Ilan作为案例研究对象进行定量分析。结果显示:与其他获奖者相比,Judit的学术生涯初创期和发展期较长;Judit是10位获奖者中唯一一位学术影响力达到顶峰时的学术年龄小于学术生产力的学者,Judit的学术创新是一个积微成著、量变催发质变的过程;其多年潜心磨砺而厚积薄发,但其获得专业认可的时间偏长;在其职业生涯中后期,一直呈现高产状态,并且存在不止一个产出高峰,发表了多篇引用率较高的经典论文,影响深远。

High performance GaSb based digital-grown InGaSb/AlGaAsSb mid-infrared lasers and bars

InGaSb/AlGaAsSb double-quantum-well diode lasers emitting around 2 μm are demonstrated. The AlGaAsSb barriers of the lasers are grown with digital alloy techniques consisting of binary AlSb/AlAs/GaSb short-period pairs. Peak power conversion efficiency of 26% and an efficiency higher than 16% at 1 W are achieved at continuous-wave operation for a 2-mm-long and 100-μm-wide stripe laser. The maximum output power of a single emitter reaches to 1.4 W at 7 A.19-emitter bars with maximum efficiency higher than 20% and maximum power of 16 W are fabricated. Lasers with the short-period-pair barriers are proved to have improved temperature properties and wavelength stabilities. The characteristic temperature(T_0) is up to 140?C near room temperature(25–55?C).

Microstructure and properties of ductile iron bars for plunger pump prepared by horizontal continuous casting process

Ductile iron bars(DIBs) with a diameter of 145 mm, used for plunger pump production, were made by the horizontal continuous casting(HCC). The microstructure of the samples cut at three locations with different distances away from the surface(~20 mm from the surface, half of the radius and the center of the HCCDIBs)were investigated. The mechanical properties were measured by tensile and torsion tests. Results show that after the spheroidization of graphite, the iron matrix incorporates the nodules of Format I, Size 8 close to the surface, Format I, Size 7 at the half of the radius from the surface, and Format II, Size 6 in the centre of the bar,according to the ASTM A247 standard. The content of pearlite in the matrix changes from 55%(~20 mm from the surface) to 70%(half of the radius) and 80%(the center of the HCCDIBs). The strengths in tension are 552, 607 and 486 MPa with the elongations of 12.5%, 10.5% and 5.8% in samples cut at these three locations from the surface to the centre, respectively. The strength in torsion is equal to 558, 551 and 471 MPa at corresponding torsion angles of 418°, 384° and 144° respectively to the same distance from the bar surface. Fracture in tension is manifested via crack propagation through the interface between graphite nodules and matrix(Mode I), while in torsion the fracture is caused by the shear of graphite nodules(Mode II). It is shown that the transition between two fracture modes is also dependent on the size of graphite nodule. Typically, fracture Mode I was observed for nodules of smaller diameter(less than 22.7 μm) and fracture Mode II was seen for nodules of greater diameter(more than 24.8 μm).

Study of seismic behavior of PHC piles with partial normal-strength deformed bars

Nine PHC piles with partial normal-strength deformed bars were prepared in present study,and cyclic loading tests were implemented to evaluate these piles’seismic performance.The influence of the axial compression ratio and the amount of normal-strength deformed bars on failure modes,crack patterns,strength,stiffness,and ductility were examined.The test findings indicate that the change of axial compression ratio has a noticeable influence on the failure mode of PHC piles.A larger axial compression ratio results in a higher cracking bending resistance,ultimate bending resistance,and initial stiffness,but the propagation heights of flexural cracks decrease as the axial compression ratio increases.Furthermore,increasing the amount of normal-strength deformed bars causes a slight decrease in ductility.Finally,a calculation formula was proposed to predict the flexural capacity of PHC piles with partial normal-strength deformed bars.

2D hierarchical lattices' imperfection sensitivity to missing bars defect

Commercially available lattices contain various kinds of morphological imperfections which result in great degradation in lattices＇ mechanical properties, therefore, to obtain imperfection insensitive lattice structure is obviously a practical research subject. Hierarchical structure materials were found to be a class of promising anti-defect materials, This paper builds hierarchical lattice by adding soft adhesion to lattice＇s cell edges and numerical results show that its imperfection sensitivity to missing bars is minor compared with the classic lattice. Soft adhesion with appropriate properties reinforce cell edge＇s bending stiffness and thus reduce the bending deformation in lattice caused by missing bars defect, which is confirmed by statistical analysis of normalized node displacements of imperfect lattices under hydrostatic compression and shear loads.