Thermal Analysis of Turbine Blades with Thermal Barrier Coatings Using Virtual Wall Thickness Method

Avirtual wall thicknessmethod is developed to simulate the temperature field of turbine bladeswith thermal barrier coatings(TBCs),to simplify the modeling process and improve the calculation efficiency.The results show that the virtualwall thickness method can improve themesh quality by 20%,reduce the number ofmeshes by 76.7%and save the calculation time by 35.5%,compared with the traditional real wall thickness method.The average calculation error of the two methods is between 0.21%and 0.93%.Furthermore,the temperature at the blade leading edge is the highest and the average temperature of the blade pressure surface is higher than that of the suction surface under a certain service condition.The blade surface temperature presents a high temperature at both ends and a low temperature in themiddle height when the temperature of incoming gas is uniformand constant.The thermal insulation effect of TBCs is the worst near the air film hole,and the best at the blade leading edge.According to the calculated temperature field of the substrate-coating system,the highest thermal insulation temperature of the TC layer is 172.01 K,and the thermal insulation proportions of TC,TGO and BC are 93.55%,1.54%and 4.91%,respectively.

Formation mechanism of bright and dark concentric-ring pattern in dielectric barrier discharge

In this work,a bright and dark concentric-ring pattern is reported in a dielectric barrier discharge for the first time.The spatiotemporal dynamics of the bright and dark concentric-ring pattern are investigated with an intensified charge-coupled device and photomultiplier tubes.The results indicate that the bright and dark concentric-ring pattern is composed of three concentric-ring sublattices.These are bright concentric-ring structures,dark concentric-ring structures and wider concentric-ring structures,respectively.The bright concentric-ring structures and dark concentricring structures are alternately distributed.The bright concentric-ring structures are located at the centre of the wider concentric-ring structures.The wider concentric-ring structures first form from the outer edge and gradually develop to the centre.The essence of all three concentric-ring structures is the individual discharge filaments.The optical emission spectra of different sublattices are acquired and analysed.It is found that the plasma parameters of the three concentricring sublattices are different.Finally,the formation mechanism of the bright and dark concentricring pattern is discussed.

Using Visual MODFLOW Model to Assess the Efficiency of Subsurface Barrier Wall for Groundwater Flow Regulation and Reduction of Saline Intrution

Barrier walls effectively store water,regulate underground flows,improve exploitable reserves and prevent saltwater intrusion.The effectiveness of the underground barrier wall depends not only on the hydrogeological structure,the technical parameters of the wall but also on the layout scheme of the exploitation well system.The results showed that in natural conditions,the ground water level upstream of the barrier wall rose in the presence of a barrier wall.In wells located downstream of high barrier walls,the water level decreased.The amount of underground current flowing into the sea decreased,the annual average value of the whole region decreased was 316 m3/day and night.In presence of a wall,both the water level and the amount of evaporation increased.The average increase in evaporation volume during the calculation period of ten thousand days with walls was 4.114 m3/d.So in presence of a wall,the amount of water that can be exploited increases by the total amount of evaporation plus the decrease in discharge to the sea and is equal to 4,424 m3/d.In the exploitation condition,if the water level in the presence of wall is kept as low as in the absence of wall,the exploitation flow will increase to about 4,400 m3/day and night.From the calculated water level values when there is a wall and without a wall,we can see that if the exploitation flow in presence of a wall and in the absence of wall is the same,the water level drop at the calculated observation wells upstream of the wall will decrease from 0.21 m to 3.97 m.The condition of effective exploitation of the wall depends on the mining scheme.The exploitation scheme is reasonable,the exploitation flow of the wells does not exceed the allowable flow so as not to cause the drying of the aquifer at the location of the well.The upstream area of the wall reflects quite clearly as the Total dissolved solids content in observation wells upstream of the wall at the end of the calculation time is significantly reduced compared to that without the wall,ranging from 69 mg/L to 5,629 mg/L.In the presence of a wall,the water level of observation wells upstream of the wall is higher than that of without a wall from 0.10 m to 0.74 m.

基于精气血津液理论的皮肤屏障损伤与修复

皮肤作为人体固有免疫系统的重要组成部分,其屏障功能发挥着至关重要的保护作用。多种皮肤病的发病与皮损屏障功能的损伤相关,皮肤屏障的修复却始终依赖于持续性外源物质的补充。中医自古有皮肤腠理卫外功能的理论,气血津液体系的正常运转维持了皮肤屏障功能的稳态,其紊乱的相关机制是多种皮肤病发病的关键病机。中医传统理论和现代生理学以人体作为共同的认知对象,为人类健康谋福祉,二者一体两面,殊途同归。白彦萍教授作为岐黄学者,在继承前人经验的基础上,总结多年的临床经验,结合皮肤屏障功能“砖墙结构”,提出以精和津液分别作为“砖块”和“灰浆”构成皮肤屏障的基本结构,血为皮肤屏障提供营养供给和排出代谢废物,气发挥主要的防御功能,精气血津液共同维持皮肤屏障功能的正常运转,形成“以精和津液为基,以血为养,以气为用”的皮肤屏障功能理论模型,并初步阐释其联络内外导致皮肤病伴随症状的理论依据,为皮肤病精气血津液层面的诊疗提供了更加详细的理论基础。

Chitin-glucan improves important pathophysiological features of irritable bowel syndrome

BACKGROUND Irritable bowel syndrome(IBS)is one of the most frequent and debilitating conditions leading to gastroenterological referrals.However,recommended treatments remain limited,yielding only limited therapeutic gains.Chitin-glucan(CG)is a novel dietary prebiotic classically used in humans at a dosage of 1.5-3.0 g/d and is considered a safe food ingredient by the European Food Safety Authority.To provide an alternative approach to managing patients with IBS,we performed preclinical molecular,cellular,and animal studies to evaluate the role of chitin-glucan in the main pathophysiological mechanisms involved in IBS.AIM To evaluate the roles of CG in visceral analgesia,intestinal inflammation,barrier function,and to develop computational molecular models.METHODS Visceral pain was recorded through colorectal distension(CRD)in a model of long-lasting colon hypersensitivity induced by an intra-rectal administration of TNBS[15 milligrams(mg)/kilogram(kg)]in 33 Sprague-Dawley rats.Intracolonic pressure was regularly assessed during the 9 wk-experiment(weeks 0,3,5,and 7)in animals receiving CG(n=14)at a human equivalent dose(HED)of 1.5 g/d or 3.0 g/d and compared to negative control(tap water,n=11)and positive control(phloroglucinol at 1.5 g/d HED,n=8)groups.The anti-inflammatory effect of CG was evaluated using clinical and histological scores in 30 C57bl6 male mice with colitis induced by dextran sodium sulfate(DSS)administered in their drinking water during 14 d.HT-29 cells under basal conditions and after stimulation with lipopolysaccharide(LPS)were treated with CG to evaluate changes in pathways related to analgesia μ-opioid receptor(MOR),cannabinoid receptor 2(CB2),peroxisome proliferator-activated receptor alpha,inflammation[interleukin(IL)-10,IL-1b,and IL-8]and barrier function[mucin 2-5AC,claudin-2,zonula occludens(ZO)-1,ZO-2]using the real-time PCR method.Molecular modelling of CG,LPS,lipoteichoic acid(LTA),and phospholipomannan(PLM)was developed,and the ability of CG to chelate microbial pathogenic lipids was evaluated by docking and molecular dynamics simulations.Data were expressed as the mean±SEM.RESULTS Daily CG orally-administered to rats or mice was well tolerated without including diarrhea,visceral hypersensitivity,or inflammation,as evaluated at histological and molecular levels.In a model of CRD,CG at a dosage of 3 g/d HED significantly decreased visceral pain perception by 14%after 2 wk of administration(P<0.01)and reduced inflammation intensity by 50%,resulting in complete regeneration of the colonic mucosa in mice with DSS-induced colitis.To better reproduce the characteristics of visceral pain in patients with IBS,we then measured the therapeutic impact of CG in rats with TNBS-induced inflammation to long-lasting visceral hypersensitivity.CG at a dosage of 1.5 g/d HED decreased visceral pain perception by 20%five weeks after colitis induction(P<0.01).When the CG dosage was increased to 3.0 g/d HED,this analgesic effect surpassed that of the spasmolytic agent phloroglucinol,manifesting more rapidly within 3 wk and leading to a 50%inhibition of pain perception(P<0.0001).The underlying molecular mechanisms contributing to these analgesic and anti-inflammatory effects of CG involved,at least in part,a significant induction of MOR,CB2 receptor,and IL-10,as well as a significant decrease in pro-inflammatory cytokines IL-1b and IL-8.CG also significantly upregulated barrier-related genes including muc5AC,claudin-2,and ZO-2.Molecular modelling of CG revealed a new property of the molecule as a chelator of microbial pathogenic lipids,sequestering gram-negative LPS and gram-positive LTA bacterial toxins,as well as PLM in fungi at the lowesr energy conformations.CONCLUSION CG decreased visceral perception and intestinal inflammation through master gene regulation and direct binding of microbial products,suggesting that CG may constitute a new therapeutic strategy for patients with IBS or IBSlike symptoms.

干拌法柔性阻隔墙在污染场地风险阻控中的应用及研究

随着“零填埋”时代的到来,中国将面临大量的存量垃圾填埋场,由于卫生填埋场防渗系统的易渗漏及非正规填埋场防渗系统的缺失,填埋场普遍存在渗漏污染地下水的风险。针对填埋场地下水风险管控,柔性阻隔墙具有渗透系数低、化学相容性好的特点,而现阶段应用相对较少。据此,文章以南方某非正规垃圾填埋场为研究对象,探究采用干拌、湿拌法工艺构筑阻隔墙的效果,发现干拌法施工工艺简单,操作便利且其构筑墙体的渗透系数达10 cm~7 cm/s级别,结合阻隔区内外的水头差可有效发挥风险阻控作用,阻隔区周边的地下水水质在监测周期内总体呈下降趋势。

钢渣/粉煤灰为骨架的混凝土阻隔墙研究

通过浸出试验、渗透试验和抗压试验研究了钢渣/粉煤灰为骨架的混凝土阻隔墙对地下水污染物的阻隔效果。结果表明:钢渣/粉煤灰混凝土阻隔墙渗透系数随着水泥、砂、水掺量的增加而降低,抗压强度随着水泥、砂、水掺量的增加而增加,阻隔墙试件浸出因子浓度均很低;实验所得的最佳配比为水泥∶砂∶钢渣/灰渣∶水∶抗渗剂=1∶1.08∶2.63∶1∶0.03,阻隔墙渗透系数为1.3×10^(-8) m/s,最大抗压强度3.5 MPa,满足地下水阻隔墙的性能要求。

Spatio-Temporal Distribution of Individual Filaments in a Square Superlattice Pattern in Atmospheric Dielectric Barrier Discharge

Spatio-temporal distribution of individual filament in a square superlattice pattern, which consists of large and small spots （filaments）, is studied in atmospheric dielectric barrier discharges. The spatial distributions of the two discharges for individual large filament along the direction perpendicular to the electrode are estimated by the distributions of light signals along the electrode. It is found that the discharge at the rising edge of the applied voltage is with a wider column, weaker current, and longer current pulse duration in comparison with that at the falling edge

Critical Length of Double-Walled Carbon Nanotubes Based Oscillators

The critical lengths of an oscillator based on double-walled carbon nanotubes(DWCNTs)are studied by energy minimization and molecular dynamics simulation.Van der Waals(vdW)potential energy in DWCNTs is shown to be changed periodically with the lattice matching of the inner and outer tubes by using atomistic models with energy minimization method.If the coincidence length between the inner and outer tubes is long enough,the restoring force cannot drive the DWCNT to slide over the vdW potential barrier to assure the DWCNT acts as an oscillator.The critical coincidence lengths of the oscillators are predicted by a very simple equation and then confirmed with energy minimization method for both the zigzag/zigzag system and the armchair/armchair system.The critical length of the armchair/armchair system is much larger than that of the zigzag/zigzag system.The vdW potential energy fluctuation of the armchair/armchair system is weaker than that of the zigzag/zigzag system.So it is easier to slide over the barrier for the armchair/armchair system.The critical lengths of zigzag/zigzag DWCNTbased oscillator are found increasing along with temperature,by molecular dynamics simulations.

汉敦煌郡之昆仑障、昆仑塞新考

昆仑障、昆仑塞是研究敦煌历史地理的重要坐标之一,其位置现有多种说法。本研究团队在野外考察发现瓜州县西荒漠中存在一段双线汉长城,修筑格局十分特殊。结合该区域周边的自然环境、城址空间分布和历史文献进一步分析,本文确定昆仑障即为该长城段南侧的巴州二号古城,昆仑候官所居可能为巴州二号古城东北2.2km长城上的城堡。该发现为我们认识该区汉长城的建设形式、汉代敦煌郡的行政区划以及交通地理提供了新证据。

航空发动机燃烧室壁面“热斑”对热障涂层失效的影响

航空发动机燃烧室壁面热障涂层的脱落直接影响着相关部件使用寿命,其重要原因是“热斑”环境下涂层的局部烧结使得涂层内具有更复杂的应力状态,从而产生新的失效模式。采用ANSYS稳态流场与ABAQUS瞬态耦合对瓦片涂层系统进行分析,并借助断裂力学与实验方法对涂层的开裂规律进行表征,结果表明涂层具有升温350℃的“热斑”表面温度场与139 MPa的内部集中剪应力,并受此影响在“热斑”边缘区域优先发生以I型载荷为主导的面内复合型开裂失效。

GCL复合垂直防渗墙中污染物运移的一维解析解

为研究膨润土防水毯(GCL)和水泥-膨润土防渗墙组成的新型复合垂直防渗墙中有机污染物的运移机理,分别考虑水泥-膨润土防渗墙和GCL作用,以及污染物击穿GCL复合垂直防渗墙迁移到零浓度的潜水层中,建立了污染物在GCL复合垂直防渗墙中的一维运移模型,并给出了出口边界采用混合边界条件时的一维解析解,所得结果与GeoStudio软件数值模拟结果高度吻合,由此验证了解析解的正确性,进而采用一维解析解开展了参数分析。研究结果表明:GCL层可以进一步提高垂直防渗墙的防污效果;有机污染物的半衰期主要影响水泥-膨润土防渗墙中的浓度分布,水泥-膨润土防渗墙的墙厚与渗透系数对墙体内部的污染物浓度分布和出口边界的污染物通量的影响较大。

海泡石改性土-膨润土泥浆阻截墙阻截地下水重金属阳离子污染

为探究海泡石的添加对土-膨润土泥浆阻截墙材料的施工和易性、渗透性,以及对地下水重金属阳离子污染阻截性的影响,采用天然海泡石对土-膨润土泥浆阻截墙改性,并以铅污染为代表,进行了坍落度实验、渗透实验和吸附实验。结果表明:添加海泡石不会对土-膨润土-海泡石阻截材料施工和易性造成太大影响,海泡石掺量从0增加至30%,满足目标坍落度要求的含水率仅增加1%;在实验掺量范围内海泡石对泥浆阻截材料渗透性能的影响较小,材料渗透系数均小于10^(-7)cm/s,能够满足工程要求;材料对Pb^(2+)的吸附是以化学吸附为主的吸附过程,海泡石掺量分别为0、5%、10%和20%时,泥浆阻截材料对Pb^(2+)的吸附量依次为89.73、112.52、140.85、183.40 mg/g,温度降低,阻截材料吸附量也随之减少。在铅污染液的作用下,土-膨润土-海泡石阻截材料渗透系数逐渐上升,海泡石的存在能够延缓Pb^(2+)对该阻截材料的侵蚀;渗出液pH和Pb^(2+)质量浓度变化表明,在实验时间内阻截材料仍然起着阻截作用。

基坑支护屏障对地铁列车引起的建筑振动隔离效果

基坑地下连续墙与回填材料构成一道隔振屏障。本文通过建立车辆-轨道-隧道-大地-建筑系统动力学模型,研究有无基坑支护屏障和采用不同回填材料时隔振屏障对地铁列车引起的建筑振动的隔离效果。结果表明:基坑支护屏障对不同楼层、不同频段振动的隔离效果不同,对地下楼层隔振效果较好,而对地上楼层隔振效果较差;回填材料类型会影响楼板振动主频和分频振级,进而影响对不同楼层的隔振效果。工程建设中应针对建筑结构和场地特征选取适宜的回填材料。

干湿循环作用下土-膨润土强度和渗透特性试验研究

由土-膨润土组成的阻隔墙在干湿循环条件下及重金属侵蚀后,强度和渗透性能严重衰减。为研究强度和渗透性能劣化程度,文中通过干湿循环条件下强度试验和渗透试验,分析无侧限强度和渗透系数的变化规律。结果表明,随着干湿循环次数的增加,无侧限强度降低和渗透系数增大,6次循环后,强度只有原来的50%左右,而渗透系数增大了几个数量级,同样循环次数下,重金属锌离子的侵入,使强度下降一半以上,渗透系数增大一个数量级。

改良隔离墙材料的强度及防渗性能研究

隔离墙常被用于临时或长期阻滞污染物扩散。基于自贡原位土研究了火山灰系改良土(未污染土/硝酸铅污染土)-水泥-膨润土(SCB)隔离墙回填料的无侧限抗压强度、渗透系数。结果表明,养护28 d后,单掺粒化高炉矿渣及粒化高炉矿渣+氧化镁部分替换水泥改良的未污染土与污染土的无侧限抗压强度均较对照组有明显增加;养护90 d后,粒化高炉矿渣部分替换水泥改良的未污染土与污染土的渗透系数较对照组减小。此外,采用火山灰系材料部分替换水泥后CO_(2)排放量较对照组明显降低。因此,改良隔离墙材料为低碳的绿色环保材料。

硬泡聚氨酯喷涂内保温冷库外墙隔汽需求计算

采用美国材料试验协会隔汽标准的计算方法对硬泡聚氨酯喷涂内保温冷库外墙隔汽需求进行了计算与分析。提出应根据冷库冷间的设计温度、所在气候分区及外墙基层材料,计算确定是否需要设置隔汽层,以及当需要设置隔汽层时,隔汽层所需的蒸汽渗透阻,并给出了不同气候分区特定工况下隔汽层蒸汽渗透阻的建议值。

基于下游引航道口门区流态的隔流墙结构形式优化措施

船闸外侧水流受枢纽下泄不稳定流的影响较大,为解决流速、流态对船舶航行的不利影响,维持引航道水流条件,分析下游引航道不稳定水流的成因,结合近年来建成的隔流墙布置方式和结构形式,通过平面布置、模型试验、资料统计分析等方法,探讨了实体墙、隔流墩、透水孔墙等诸多结构形式对水流条件的影响,研究提出多种引航道隔流墙结构布置形式和优化措施方案。

污染场地原位立体防渗阻隔措施浅析

文中对某污染场地原位立体防渗阻隔措施进行分析,通过对原位立体防渗阻隔应用技术的研究,为其他类似污染地块修复治理提供参考。该项目相关技术已申请国家实用新型专利、青岛市建筑工法,具有较好的经济、社会效益。

插风墙与草方格沙障源流考

插风墙与草方格沙障原理相同,推测二者之间存在源流关系。文献调研结合中国数字植物标本馆搜索,考证表明:草方格由刘慎谔先生创建于1953年,1956年被用于包兰铁路沙坡头段固沙以免沙埋路基;插风墙最早见载于1691年,被用于绿洲农田边以阻挡风沙保护禾苗,或被用于固沙以免压埋农庄,1950年在甘肃金塔绿洲被直接用于治沙,其在金塔绿洲的应用历史应该由来已久;1931年刘慎谔先生在金塔绿洲的黑河岸边天仓村采集植物标本5日。因此,不能否定刘慎谔先生在天仓村见过插风墙,由此开始思索治沙科学,进而创建草方格沙障。