传统过夜受精与短时受精在继发不孕患者体外受精中的应用效果比较

目的探讨传统过夜受精与短时受精在继发不孕患者体外受精中的应用效果。方法回顾性分析2019年1月至2021年10月于九江市妇幼保健院生殖中心因不孕不育进行体外受精-胚胎移植(IVF-ET)助孕的462个周期继发患者的临床资料,根据不同IVF方案分为短时受精组[239个周期,胞浆内单精子显微注射(ICSI)周期除外]与传统过夜受精组(223个周期,ICSI周期除外)。两组移植周期均为49个周期。比较两组受精情况、两原核(2PN)率、卵裂率、优胚率、囊胚形成率、优质囊胚率、胚胎利用率及临床妊娠率等情况。结果两组MⅡ卵率、0PN率、1PN率、≥3PN率比较差异无统计学意义;传统过夜受精组2PN率高于短时受精组,差异有统计学意义(P<0.05)。两组卵裂率、优胚率、囊胚形成率、优质囊胚率、胚胎利用率、临床妊娠率比较差异无统计学意义;传统过夜受精组受精率高于短时受精组,差异有统计学意义(P<0.05)。结论传统过夜受精可作为继发不孕患者首选受精方式之一,可以提高卵子利用率及受精率,且不影响胚胎发育质量。

十字形钢管束自密实混凝土短肢剪力墙轴压性能研究

为研究十字形钢管束自密实混凝土短肢剪力墙的轴压受力性能,通过模型试验研究和ABAQUS数值模拟相结合的方法,对不同腔体数十字形钢管束自密实混凝土短肢剪力墙的轴压性能进行分析。首先,根据轴压试验结果对剪力墙的破坏形态和轴向荷载-应变曲线等轴压受力性能进行分析,提出轴压承载力计算公式。其次,建立剪力墙轴压有限元计算模型,将试验结果和模型计算结果进行对比以验证有限元模型的准确性。最后,根据有限元参数化分析结果验证并修正剪力墙轴压承载力计算公式。研究发现,剪力墙的轴向荷载-应变曲线在不同腔体数下具有相似的特征,表明其变形能力良好。在破坏过程中,钢管束对核心混凝土的约束作用显著,提高了试件的延性和承载能力,其中钢管束的破坏主要表现为多波鼓曲和焊缝开裂,尤其是在钢管束中部的1/4区域。此外,随着腔体数增加,剪力墙极限承载力提升,但其延性系数有所下降。本研究提出的简化公式与有限元分析结果的误差控制在10%以内,该公式可为工程设计应用提供理论借鉴。

短管直径对短管蜂窝夹套传热性能的影响

基于某工程中1台干燥机的短管蜂窝夹套结构形式,通过将短管尺寸由Ф90 mm×5 mm逐渐增大到Ф135 mm×7.5 mm,建立了模型1~模型6共6种夹套流场计算有限元模型,模拟分析了各模型速度场和温度场分布特性,计算并对比了各模型在不同体积流量下的总传热系数。模拟数据表明,随着短管尺寸的增大,夹套流体域内最大流速呈持续递减趋势。随着短管尺寸的增大,夹套流体域内温度场均匀性先升后降,模型5温度场分布均匀性最佳,总传热系数最大。随着体积流量的增加,夹套总传热系数持续增大。随着短管直径的增大,夹套总传热系数先升后降,模型5总传热系数最大。综合分析表明,在一定范围内增大短管的直径,能够强化夹套传热效果。

异形多腔钢管混凝土分叉短柱抗震性能试验及数值计算

针对某超高层巨型框架结构中异形截面多腔钢管混凝土(concrete-filled steel tube, CFT)分叉柱,为研究截面加强构造对分叉短柱抗震性能的影响,进行了4个试件在竖向轴压力及水平往复两次的低周反复荷载下的抗震性能试验研究,试件上部为五边形四腔体钢管混凝土双柱肢,下部为八边形十三腔体钢管混凝土单柱肢,以此形成分叉柱;研究的截面构造包括四种:基本构造,钢管钢板整体加厚构造,距中和轴较远的钢管角部钢板内表面贴焊等肢角钢的局部钢板加厚构造,距中和轴较远的钢管腔体内置圆钢管构造。基于试验结果及截面构造特点,进行了数值计算。试验及数值计算结果表明:异形截面多腔钢管混凝土分叉短柱的破坏主要发生在上柱根部分叉截面处,表现为距离中性轴较远处的钢板撕裂以及局部焊缝开裂引起的整块钢板撕裂;内置圆钢管的加强构造承载力提高7.6%、变形能力提高14.4%,综合耗能能力最强,局部钢板加强构造承载力提高9.2%、变形能力下降18.7%,钢管钢板整体加厚构造承载力略有提高、但变形能力下降较多;提出的异形多腔钢管混凝土柱简化建模方法计算效率较高,精度满足工程设计要求。

带肋方钢管混凝土轴压短柱承载性能有限元分析

带肋方钢管混凝土是一种具有卓越性能被广泛应用的结构材料。使用ABAQUS有限元软件,对方钢管混凝土短柱进行了有限元分析,得出了方钢管混凝土短柱在轴向压力下的荷载-位移全过程关系曲线。增加加劲肋的设计,可以有效提高方钢管混凝土短柱的承载能力;随着加劲肋个数和钢管厚度的增加,构件的极限承载力也得到了提高。

基于ABAQUS的圆钢管混凝土短柱受火力学性能研究

基于ABAQUS有限元软件建立了温度场和力学性能分析模型,将模拟结果与试验结果进行比对,验证了模型的可靠性。在此基础上建立了钢管混凝土短柱在高温火灾下的均匀受火和三面受火轴压的温度场模型,探讨了截面尺寸、钢管强度、混凝土强度、受火方式等因素与高温(受火)下钢管混凝土短柱的力学性能之间的关系。

套筒强夯长短桩复合地基承载特性研究

【目的】随着大型海洋工程项目不断发展,对水下软土地基处理提出了新的挑战,水下挤密砂桩和水下水泥搅拌桩复合地基等传统方法具有定位难、制桩难、桩体质量差等问题,始终制约着其在海洋工程中的应用和发展。【方法】借鉴陆上孔内深层强夯施工方法,因地制宜地提出水下套筒强夯复合地基成桩技术,该技术使用套筒阻隔海水进入桩孔,具有定位准、加固深和强度高等优点,通过模型试验的方法对该技术进行研究。【结果】结果表明,在强夯碎石桩与传统碎石桩相结合的工况下,地基极限承载力提高50%以上,等长度群桩复合地基极限承载力比长短桩复合地基提升18%;在全部采用强夯碎石桩的工况下,地基极限承载力提高170%以上,等长度群桩复合地基极限承载力比长短桩复合地基提升3.7%。【结论】全部采用强夯碎石桩的复合地基比强夯碎石桩与传统碎石桩组合而成的复合地基承载力提高更多,在提高承载力方面,采用套筒强夯长短桩复合地基更加经济有效。

Macrostructure and properties of thin walled copper tubes prepared by the downward continuous unidirectional solidification method

The macrostructure and properties of the thin walled copper tube prepared by the downward continuous unidirectional solidification （DCUS） method were studied. The result shows that the macrostructure is closely related to the solid-liquid interface profile, which is influenced by the distance between the cooling water location and the solidification front. The mechanical properties of the thin walled copper tube prepared by the DCUS method are near those of the normal cast copper, and it has good relative density, electrical conductivity, and elongation, which are not greatly affected by casting speed. The thin walled copper tube prepared by the DCUS method also has good processing properties that can be taken to further drawing procedures directly without an intermediate process, and obtains good mechanical properties with the total processing rate of 89.8%.

Analysis of High-temperature Boiler Tube Failure for T91 &T22

The tube failures took place frequently in the superheater of 2x600MW units in a power plant. According to the condition of tube failures, the mechanical property and microstructure on running and failed tubes were tested and evaluated. The chemical composition and structure phase of inner oxide scale and deposit inside of the tubes were examined.The fractured surfaces of failed tube samples were observed. And the material examination was performed for original tube steels SA213-T91 and SA213-T22. The results show that raw materials of SA213-T91 and SA213-T22 tube in superheater are qualified. Besides, the characteristics of the SA213-T91 and SA213-T22 tube failure are typical short-term overheated rupture. The rupture temperature is located between two phase Ac1 ～ Ac3 of the two steels. It is recognized that putting SA213-T22 tubes in operation under the condition of long-term over heating causes the rupture of SA213-T91 and SA213-T22.

Inhibition of germ tube's formation of Candida albicans by lactobacillus spp.

Objective:To investigate the effects of 6 strains of lactobacilli and their main culture metabolites on the morphogenesis of Candida albicans (C. albicans) so as to screen medicinal strains as antifungal agents. Methods: Spent culture supernatant (SCS) at different culture time points, live lactobacilli, heatkilled bacteria and bacterial short-chain fatty acids (SCFA) with different molarities were incubated with C. albicans respectively. Crystal violet-based germ tube assay was used to detect the germination of C. albicans and the inhibitory efficiency of each addition was tested by germination rate. Results: SCS of lactobacillus spp. decreased the germination significantly and live bacteria of L. rhamnosus. GG, L. acidophilus L050103-12 as well as L. johnsonii JCM1022 could partially inhibit the conversion, however, all the heatkilled bacteria failed to control the germ tube formation. In addition, only butyric acid blocked the conversion of yeast to hypha among all the SCFA. Conclusion: The excellent fungistasis activities make L.rhamnosus. GG, L. acidophilus L050103-12 and L. johnsonii JCM1022 potential strains as antifungal drugs and the inhibition seems to have direct correlation to the metabolites.

短管节流阀内流动噪声的实验研究及降噪措施

短管节流阀作为节流机构,因其结构简单而广泛应用于家用空调器中,当两相状态的制冷剂流经短管节流阀时会产生严重的噪声。设计并搭建了短管节流阀流动噪声测试台,实验研究了制冷剂流型、流量和干度对短管节流阀内流动噪声频率和声压级的影响规律,并在此基础上提出了降噪措施。实验结果表明,阀进口流型为搅浑流时产生的流动噪声声压级最大,阀进口流型为泡状流型和环状流型时产生的流动噪声较小;流动噪声的峰值频率随质量流量的增大而增大,质量流量由20 kg/h增大到80 kg/h时,流动噪声的峰值频率增大38.6%;干度由0.05增大到0.4时,流动噪声的平均声压级先增大7 dB,后减小3 dB。提出了将阀芯入口处的突扩突缩结构改为喇叭口渐缩结构的方式来实现降噪的结构优化方案,优化后的结构方案可将流动噪声的平均声压级降低2 dB。

Behavior of eccentrically loaded concrete-filled GFRP tubular short columns

The glass fiber reinforced polymer (GFRP) tube is an effective material that can increase the bearing capacity and ductility of concrete.To study the mechanical behavior of this composite structure,twenty-one concrete-filled GFRP tubular short columns were tested under an eccentric load.The principle influencing factors,such as the eccentricity ratio,concrete strength and ratio of longitudinal reinforcement were also studied.In addition,the course of deformation,failure mode,and failure mechanism were analyzed by observing the phenomena and summarizing the data.The test results indicated that the strength and deformation characteristics of core concrete increase as a result of the addition of the GFRP tube.However,the gain in strength due to the addition of the GFRP tube decreases as the ratio of e /d increases.An increase in the longitudinal steel ratio can improve the bearing capacity of the composite short column effectively.Furthermore,the study showed that the constraint effect of the GFRP tube on high-strength concrete is not as effective as that on common concrete.The reason is that the lateral deformation of the high-strength concrete is less than that of the common concrete when the concrete column was tested under the same axial compression ratio.

氯盐腐蚀圆钢管再生混凝土短柱轴压承载力分析

为研究氯盐腐蚀圆钢管再生混凝土短柱轴压承载性能的变化规律,设计了16个试件并完成轴压试验。在试验研究的基础上根据极限平衡条件,提出了氯盐腐蚀条件下钢管再生混凝土短柱轴压承载力的计算公式,选取不同的侧压系数进行对比优化;采用国内外常用规范对试件承载力进行计算,将计算值与试验值进行对比并提出使用建议。结果表明给出的侧压系数建议值与试验结果吻合较好,通过折减壁厚的方法计算承载力是可靠的,对氯盐腐蚀圆钢管再生混凝土柱的理论研究和工程应用有一定的指导意义。

Prediction of Axial Capacity of Concrete-Filled Square Steel Tubes Using Neural Networks

The application of artificial neural network to predict the ultimate bearing capacity of CFST （ concrete-filled square steel tubes） short columns under axial loading is explored. Input parameters consiste of concrete compressive strength, yield strength of steel tube, confinement index, sectional dimension and width-to-thickness ratio. The ultimate bearing capacity is the only output parameter. A multilayer feedforward neural network is used to describe the nonlinear relationships between the input and output variables. Fifty-five experimental data of CFST short columns under axial loading are used to train and test the neural network. A comparison between the neural network model and three parameter models shows that the neural network model possesses good accuracy and could be a practical method for predicting the ultimate strength of axially loaded CFST short columns.

中空夹层钢套铝管混凝土短柱轴压性能试验研究

为研究中空夹层钢套铝管混凝土短柱的轴压性能,通过改变参数的方法对8根构件开展了轴压试验,构件中空率为0.38、0.51、0.78,混凝土强度为普通混凝土C30、轻质混凝土C30,内铝合金管壁厚为5 mm和3 mm;依据中空夹层钢管混凝土短柱的轴压承载力公式,对约束效应系数进行修正,最终得出拟合性较好的中空夹层钢套铝管混凝土短柱轴压承载力计算公式。结果表明:构件的破坏形态为跨中部或端部发生鼓曲,其中外钢管向外鼓曲,核心混凝土被压碎,内铝合金管向内凹陷;中空率为0.78和0.51的构件较中空率为0.38的构件极限承载力分别提高29%、19%,普通混凝土构件的极限承载力相较于轻质混凝土构件提升60%;内管壁厚为5 mm的构件相较于内管壁厚为3 mm的构件承载力提高约2%;构件的承载力大小随着中空率的减小而增加,随着混凝土强度等级的增加而增加,随着内铝合金管壁厚的增加而增加。

硫酸盐环境下GFRP管混凝土柱轴压性能演化规律

硫酸盐长期腐蚀会导致混凝土结构性能退化,纤维增强聚合物(FRP)与混凝土组合结构具有良好的抗腐蚀性能。对玻璃纤维增强聚合物(GFRP)管混凝土短柱采用硫酸盐浸泡和干湿循环两种作用方式开展腐蚀试验,通过表观现象观察、质量损失测试、超声探测等,研究组合柱在硫酸盐作用下结构变化特征;开展轴压试验,测试极限承载力与荷载-应变曲线,对比分析GFRP管混凝土短柱轴压性能演化规律。结果表明:在硫酸盐环境中,GFRP管能抵抗硫酸盐的侵蚀,有效保护混凝土,确保组合柱抗压强度。硫酸盐溶液浸泡和干湿循环作用降低了GFRP管混凝土短柱的强度以及延性,且随着腐蚀时间的增加,硫酸盐干湿循环作用比浸泡作用下对GFRP管混凝土短柱造成的缺陷更多,GFRP管与混凝土协同作用略微降低。

绿色纤维钢管混凝土轴压性能有限元分析

为研究绿色纤维对方钢管混凝土短柱受力性能的影响,通过ABAQUS对不同纤维体积掺量钢管混凝土短柱进行数值模拟分析,共设计3组试件,纤维掺入量分别为0%、1%、1.5%,通过观察不同掺量下构件的变形图以及荷载-位移曲线来研究绿色纤维对其构件力学性能的影响。结果表明绿色纤维对构件的横向变形影响较大,随着掺入量的增加,绿色纤维对构件的承载能力有明显提高,改善了构件的脆性和延性,并提高了整体构件的力学性能。

腹膜透析外接短管固定背心的临床应用

目的:探讨外接短管固定背心在腹膜透析病人中的应用效果。方法:选取2021年8月—2022年8月在本院行维持性腹膜透析治疗的病人90例,采用随机数字表法分为观察组和对照组,各45例。对照组使用传统腹带,观察组使用腹膜透析外接短管固定背心。比较两组试穿期间腹膜炎发生率、出口处皮肤并发症、换液操作时间、产品的医疗成本、病人舒适度和满意度、导管牵拉、卡夫(固定装置)脱出次数。结果:观察组腹膜炎发生率、出口处皮肤并发症发生率较对照组更低,换液操作时间较对照组更短,医疗成本更少,病人舒适度和满意度更高;且观察组导管牵拉、卡夫脱出次数较对照组少,差异均有统计学意义(P<0.05)。结论:将腹膜透析外接短管固定背心应用于腹膜透析病人中,临床效果较好。

偏心率对工字型CFRP-高强圆钢管高强混凝土短柱力学性能的影响

目的研究偏心率对内置工字型CFRP型材的高强圆钢管高强混凝土短柱力学性能的影响。方法利用ABAQUS有限元软件建立了工字型CFRP-高强圆钢管高强混凝土短柱模型,分析不同偏心率下构件的受力-变形关系、各材料分担荷载以及应力发展,探究混凝土强度、钢材屈服强度、含钢率和CFRP型材对组合柱力学性能的影响。结果随着偏心率的增大,构件延性提高,初始刚度与极限承载力降低,且降低幅度减小,偏心率与极限承载力呈非线性关系;偏心率越小,加入CFRP型材对组合柱承载力的提高越显著。结论偏心率越大,混凝土强度的利用率越低,钢管力学性能发挥越充分。偏心率小于0.328时,建议采用增大混凝土强度的方式增加构件极限承载力;偏心率大于0.328时,建议采取增大钢材屈服强度和含钢率的方式增加构件的极限承载力。