深基坑管井降水理论的实际应用

本文从工程实际出发,诠释了泰斯公式在具体工程上的应用条件和环境,并运用了工程实际,收到了较好的效果。     

Conifers and commemoration — the politics and protocol of planting

This study examines the symbolic role of trees, shrubs and flowers on 20th century battle grounds and military cemeteries. By focusing on the imagery of commemoration and on the power of horticultural symbols the paper explores the emergence of an iconography during wartime and its perpetuation in ritualized peacetime landscapes. The paper makes specific reference to the Western Front in France and Belgium, and to the consecrated ground of the Dardanelles peninsula — a commemorative terrain that is being altered by Turkish planting and memorial schemes that are bringing into sharp focus the problems of maintaining Christian burial grounds in perpetuity across the globe. The paper concludes by asking whether tree planting may have replaced memorial building in the rhetoric and culture of commemoration.     

T型薄壁管节点应力集中系数有限元分析

通过有限元的方法,分析了T型薄壁管节点受平面内弯矩作用下的疲劳行为,得到了应力最大值的位置和拟合出用于预测T型薄壁管节点受平面内弯矩作用下的应力集中系数的参数公式。     

一种固化河湖底泥重金属的改良方法

重金属在河湖底泥中的积聚已成为我国的一大环境问题,通过及时妥善的技术处理,可以避免重金属对环境的二次污染。基于生石灰降低底泥含水量,锯末灰初步固化,采用水泥和矿粉+水泥2种方式对生石灰-锯末灰固化后的污泥进一步固化的方法,对天津西青区某河流污染底泥开展试验。基于原子吸收分光法对试验样品进行重金属浸出浓度分析,比较水泥和矿粉+水泥固化2种方法的固化效果。研究表明,当生石灰掺入比为9%,养护2 d 时,污泥的含水率明显降低。锯末灰掺入比10% 、水泥掺入比20%、矿粉换掺水泥40%时,底泥中的 Ni²⁺ 、 Hg²⁺ 、 Pb²⁺ 、 Cd²⁺ 4种超标重金属浸出浓度分别降低71.61%、84.85%、58.49%、77.78%,均满足相关技术规范要求。为检验固化土的种植效果,选用牛筋草和牛繁缕2种植物进行室内60 d种植试验,发现2种植物的光合作用、根部发育、生长速度都很正常。结果表明生石灰掺入比9%、锯末灰掺入比10%、水泥掺入比20%、矿粉换掺水泥40%的固化方案得到的固化土可用于绿化种植。     

Modulation of Tubular pH by Acetazolamide in a Ca2+ Transport Deficient Mice Facilitates Calcium Nephrolithiasis

Proximal tubular (PT) acidosis, which alkalinizes the urinary filtrate, together with Ca²⁺ supersaturation in PT can induce luminal calcium phosphate (CaP) crystal formation. While such CaP crystals are known to act as a nidus for CaP/calcium oxalate (CaOx) mixed stone formation, the regulation of PT luminal Ca²⁺ concentration ([Ca²⁺]) under elevated pH and/or high [Ca²⁺] conditions are unknown. Since we found that transient receptor potential canonical 3 (TRPC3) knockout (KO; -/-) mice could produce mild hypercalciuria with CaP urine crystals, we alkalinized the tubular pH in TRPC3-/- mice by oral acetazolamide (0.08%) to develop mixed urinary crystals akin to clinical signs of calcium nephrolithiasis (CaNL). Our ratiometric (λ340/380) intracellular [Ca²⁺] measurements reveal that such alkalization not only upsurges Ca²⁺ influx into PT cells, but the mode of Ca²⁺ entry switches from receptor-operated to store-operated pathway. Electrophysiological experiments show enhanced bicarbonate related current activity in treated PT cells which may determine the stone-forming phenotypes (CaP or CaP/CaOx). Moreover, such alkalization promotes reactive oxygen species generation, and upregulation of calcification, inflammation, fibrosis, and apoptosis in PT cells, which were exacerbated in absence of TRPC3. Altogether, the pH-induced alteration of the Ca²⁺ signaling signature in PT cells from TRPC3 ablated mice exacerbated the pathophysiology of mixed urinary stone formation, which may aid in uncovering the downstream mechanism of CaNL.     

敞口管型桩压入对既有受荷桩基承载性状影响

基于经典桩侧摩阻力公式和圆孔扩张理论,优化考虑土压力系数、土塞增长率、扩孔塑性半径等问题,计算新增管桩的植入对在役桩承载性状的影响. 对比分析有限元的软件与理论计算结果,发现管型桩贯入引致的桩间土挤土效应,使在役桩侧摩阻力在一定深度范围内增加,且桩长越长、桩间距越小,贡献越明显. 新增桩与在役桩的距离小于3倍桩径,会形成局部群桩效应,使群桩协同工作时的桩顶沉降增加;距离大于6倍桩径,管型桩压入对既有桩侧摩阻力、群桩协同工作效应的影响较小.     

焊接箱型截面构件在不同焊缝熔深下承载力性能试验研究

为了有效改善大跨度桥梁中管翼缘焊接箱型截面构件的耐久性的问题,提出采用耐候钢代替普通钢的管翼缘箱型截面梁。同时,为了研究耐候钢管翼缘焊接箱型截面构件填充混凝土后在全熔透和部分熔透条件下的单轴承载力性能,开展了焊接矩形截面在三种不同焊缝熔深下的耐候钢管混凝土截面轴压短柱试验研究。分别测试每个试件在单轴压力作用下的静态应变、动态应变,以及竖向位移和侧向位移。对比构件承载力的试验结果及理论分析结果,得出不同熔深下焊接箱型截面管翼缘组合构件的承载力性能。研究结果表明:1）耐候钢管翼缘焊接箱型截面构件的全熔透焊缝承载力高于部分熔透焊缝承载力。2）全熔透试件开裂时的竖向位移较部分熔透试件的位移值大,而不同熔深下构件的横向位移测点L4随轴压荷载的增大而有增加,L3测点横向位移规律不明显。3）不同耐候钢管翼缘焊接箱型截面构件横向整体受拉,局部在顶部角部位置受压。构件的混凝土内部和钢板表面应变情况复杂,规律不明显。     

后置导叶对潮汐双向贯流式机组性能的影响

潮汐双向贯流式水轮机与常规贯流式水轮机的重要区别在于其需要兼顾正向和反向来流工况。为了均衡提升双向贯流式水轮机正反向运行条件下的性能,针对某潮汐双向贯流式水轮机,本文采用商业软件ANSYS CFX,研究了不同后置导叶位置和数量对双向贯流式水轮机性能及内部流动特性的影响。对比结果可知,后置导叶位置和后置导叶数量对机组反向发电时的性能影响较大,后置导叶安放位置系数为0.5和后置导叶数量为8时,机组总体性能较好。随着后置导叶数量增加,正向工况时尾水管水力损失减小,后置导叶通道水力损失反而增大;反向工况时转轮水力损失不断减小,转轮效率逐渐增大。研究成果为潮汐双向贯流式水轮机关键过流部件的优化设计提供技术参考。     

高弹性MXene/TPU纳米纤维纱线的制备及其应变传感性能

采用静电纺丝技术制备了热塑性聚氨酯弹性体(TPU)纳米纤维膜,并通过“Biscrolling”的方法制备高弹性过渡金属碳化物/氮化物（Ti3C2Tx MXene）改性TPU纳米纤维纱线。通过SEM、电阻测试、传感性能测试等对复合纳米纤维纱线进行结构和性能表征。结果显示,随着MXene负载量增加,复合纱线的强度先增加后降低,断裂伸长率可高达459%以上,展现出优异的弹性和弹性回复性;MXene片可在纳米纤维纱线表面及内部形成连续导电薄膜,赋予复合纱线较好的导电性（电阻76 Ω/cm）。纱线的应变传感性能测定实验表明,MXene/TPU纳米纤维纱线的传感系数可高达477.86,线性度高达0.995,高于绝大多数文献报道的纱线传感器,并且可以监测人体的各种运动状态,展现出较好的应变传感性能,在智能可穿戴领域展现出广泛的应用前景。     

CO2/H2S对油气管材的腐蚀规律

本文综述了CO2、H2S对油气管材的腐蚀机理及影响因素,提出了开发经济型油管的设想.