Analysis of debris flow control effect and hazard assessment in Xinqiao Gully,Wenchuan M_(s)8.0 earthquake area based on numerical simulation

Xinqiao Gully is located in the area of the 2008 Wenchuan M_(s)8.0 earthquake in Sichuan province,China.Based on the investigation of the 2023"6-26"Xinqiao Gully debris flow event,this study assessed the effectiveness of the debris flow control project and evaluated the debris flow hazards.Through field investigation and numerical simulation methods,the indicators of flow intensity reduction rate and storage capacity fullness were proposed to quantify the effectiveness of the engineering measures in the debris flow event.The simulation results show that the debris flow control project reduced the flow intensity by41.05%to 64.61%.The storage capacity of the dam decreases gradually from upstream to the mouth of the gully,thus effectively intercepting and controlling the debris flow.By evaluating the debris flow of different recurrence intervals,further measures are recommended for managing debris flow events.

An Improved Coupled Level Set and Continuous Moment-of-Fluid Method for Simulating Multiphase Flows with Phase Change

An improved algorithm for computing multiphase flows is presented in which the multimaterial Moment-of-Fluid(MOF)algorithm for multiphase flows,initially described by Li et al.(2015),is enhanced addressing existing MOF difficulties in computing solutions to problems in which surface tension forces are crucial for understanding salient flow mechanisms.The Continuous MOF(CMOF)method is motivated in this article.The CMOF reconstruction method inherently removes the"checkerboard instability"that persists when using the MOF method on surface tension driven multiphase(multimaterial)flows.The CMOF reconstruction algorithm is accelerated by coupling the CMOF method to the level set method and coupling the CMOF method to a decision tree machine learning(ML)algorithm.Multiphase flow examples are shown in the two-dimensional(2D),three-dimensional(3D)axisymmetric"RZ",and 3D coordinate systems.Examples include two material and three material multiphase flows:bubble formation,the impingement of a liquid jet on a gas bubble in a cryogenic fuel tank,freezing,and liquid lens dynamics.

Non-Darcy Flow in Molding Sands

Darcy’s law is widely used to describe the flow in porous media in which there is a linear relationship between fluid velocity and pressure gradient. However, it has been found that for high numbers of Reynolds this law ceases to be valid. In this work, the Ergun equation is employed to consider the non-linearity of air velocity with the pressure gradient in casting sands. The contribution of non-linearity to the total flow in terms of a variable defined as a non-Darcy flow fraction is numerically quantified. In addition, the influence of the shape factor of the sand grains on the non-linear flow fraction is analyzed. It is found that for values of the Reynolds number less or equal than 1, the contribution of non-linearity for spherical particles is around 1.15%.

甘肃积石山 M_(s)6.2级地震的震害特征与启示

2023年12月18日,甘肃省临夏回族自治州积石山保安族东乡族撒拉族自治县(35.70°N,102.79°E)发生了6.2级地震,震中烈度为VIII度。地震发生后,通过实地烈度评估与科学考察,对震区VI~VIII度区不同建(构)筑物与生命线工程的震害特点进行了统计分析;从抗震设计与施工管理、场地放大效应与地震次生灾害对建筑结构抗震性能的影响等角度,提出了此次地震的震害启示。结果表明:1)严重破坏和毁坏的建筑结构主要集中在老旧的土木结构、砖木结构和无设防或设防不规范的砖混结构。2)造成建筑结构破坏的主要原因是少量自建房抗震设计和施工的不规范、场地放大效应和地震次生灾害。3)优化和改良生土砌筑材料,改进纵横墙间的拉结措施,强化结构整体性是提高土木结构抗震的有效方法;普及“上下圈梁与构造柱”等基本抗震设防措施,规范水泥砂浆强度,提升农村工匠的施工水平,可有效提高砌体结构的整体性,避免房屋出现整体性垮塌;室内洗手间的墙体应该与房顶、纵横墙间建立有效联接,提高结构的抗震性能。4)孤突斜坡、河流高阶地与岸边为抗震不利地带。当建造用地极为匮乏,不得不选址在这些场地之上时,应该综合考虑场地的地形地貌特征、岩土体物理力学特性、水文地质条件、抗震设防目标、建筑结构类型等影响因素,做好地震灾害风险评估,根据评估结果进行科学设防。灾后重建过程中,应由政府统一规划选址、统一设计,规范施工。

Temporal change of plankton size structure preserved by Lugol's solution:a FlowCAM study

Plankton size structure is crucial for understanding marine ecosystem dynamics and the associated biogeochemical processes.A fixation step by acid Lugol’s solution has been commonly employed to preserve plankton samples in the field.However,the acid Lugol’s solution can bias the estimation of size structure and the preserved plankton size structure can vary with time.Here,we explore the impact of sample storage time on the size-structure of the plankton community preserved by Lugol’s solution.Two short-term experiments and one long-term experiment were conducted to explore the change of plankton community size structure with the storage time:covering from a week to a month,and to nearly seven months based on particle-size data obtained by continuous Flow Cytometer and Microscope(FlowCAM)measurements.We found a linear change of plankton size with the storage time in short-term periods(less than 3 months)with a decrease of the slope but an increase of the intercept for the normalized biomass size spectrum(NBS S).However,there were opposite trends for NBSS with increasing slope but decreasing intercept after3 months.The potential causes of the distinct patterns of the NBSS parameters are addressed in terms of the interplay between particle aggregation and fragmentation.We found large changes in plankton biovolume and abundance among different size classes,which may indicate a distinct effect of acid Lugol’s solution on various plankton size classes.The mechanism driving temporal change in the size-structure of the Lugolfixed plankton community was further discussed in terms of particle aggregation and fragmentation.Finally,we emphasize that the effect of storage time should be taken into account when interpreting or comparing data of plankton community acquired from samples with various storage durations.

S弯收扩喷管过膨胀状态下流动分离特性研究

为了研究S弯收扩喷管过膨胀状态下的流动分离特性,数值模拟了不同落压比(NPR)下S弯收扩喷管内的流动特征。结果表明:在落压比为2.0时,喷管内发生非对称分离,出现非对称的双“λ”激波结构,喷流整体向上偏转,上侧出现限制性流动分离RSS,下侧出现自由性流动分离FSS,并产生三维分离涡,喷流出现明显的三维效应。随着落压比从高度过膨胀状态下开始增加,喷管下侧保持FSS不变,喷管上侧RSS逐渐向后移动,直至与外界大气相连,转变为FSS,之后随着落压比增加,上下侧分离结构逐渐对称。推力矢量角随着落压比的增加先增加,后在极小的落压比变化范围内快速降低,直至变为0°,之后保持0°不变。

S型皮托管对向和非对向测量方法准确度实验研究

S型皮托管的对向和非对向测量方法准确度在不同工况下有较大差异。通过风洞实流实验对风速、流速攻角和结构参数对S型皮托管对向和非对向测量方法准确度的影响进行了研究。结果表明:风速由5 m/s变化至30 m/s时,在不同流速攻角下S型皮托管对向和非对向测量准确度最大差异超过10%;对向和非对向测量中静压孔的压力变化是皮托管在较大流速攻角下造成测量误差的主因;外径较小、总静压孔距较大、测量端弯曲角度在15°至30°间、取压孔内径更小的S型皮托管在对向和非对向测量中都有更高的测量准确度;俯仰角取正值时对向测量准确度全面优于非对向测量,在俯仰角和偏航角同为45°时测量准确度差异达到最大值,大于70%。

基于Hansbo渗流的平面应变固结分析

为了考察非Darcy渗流对二维地基固结过程的影响,引入Hansbo渗流方程描述饱和黏性土中的渗流规律,修正了Terzaghi-Rendulic平面应变固结方程,并给出了有限体积法数值求解格式;采用不同的Hansbo渗流参数,分析了条形荷载作用下有限深度地基的固结特性。结果表明:Hansbo渗流延缓了平面应变固结的过程,并且随着Hansbo渗流参数的增大,超静孔压的消散变得更为缓慢,因此,按Darcy渗流对二维地基进行的常规固结分析将会高估其固结速率;与Biot固结理论相比,在Terzaghi固结理论框架内,条形荷载下固结初期地基中局部的孔压增大现象并不明显。研究成果可为探寻更为准确的饱和黏性土地基沉降预测方法提供理论基础。

“Λ”型凸台对低隔道亚声速S弯进气道的流场控制研究

针对某无人机进气系统低隔道亚声速S弯进气道出口流场畸变较大的问题,研究一种利用隔道内置“Λ”型凸台生成反向涡抑制出口畸变的流场控制手段。通过数值仿真分析“Λ”型凸台结构对抑制流场畸变的作用机制,给出不同来流条件下凸台结构参数对进气道出口总压恢复系数和流场畸变的影响规律。研究表明:畸变控制效果与凸台几何尺寸密切相关,合理设计的凸台对出口畸变抑制效果明显。

Effects of reservoir fluids on sand packs consolidated by furan and epoxy resins:Static and dynamic states

One of the most effective methods for sand control is the chemical consolidation of sandstone structures.In this paper,the impacts of crude oil and brine in the static state and the impact of the flow rates of the fluids in the dynamic state have been assessed at the reservoir conditions.The analyses in this research were Young’s modulus,compressive strength,porosity,and permeability which were done on core samples after and before fluid contact.Samples made with two different resins showed good resistance to crude oil in both states.No considerable change was seen in the analyses even at high crude oil injection rates in the dynamic state.Conversely,brine caused a noticeable change in the analyses in both states.In the presence of brine at the static state,Young’s modulus and compressive strength respectively decreased by 37.5%and 34.5%for epoxy cores,whereas these parameters respectively reduced by 30%and 41%for furan cores.In brine presence at the dynamic state,compressive strength reduction was 10.28 MPa for furan and 6.28 MPa for epoxy samples and their compressive strength reached 16.75 MPa and 26.54 MPa respectively which are higher than the critical point to be known as weak sandstone core.Moreover,Young’s modulus decrease values for furan and epoxy samples were respectively 0.37 GPa and 0.44 GPa.Therefore,brine had a more destructive effect on the mechanical characteristics of samples in the static state than the dynamic one for two resins.In addition,brine injection increased permeability by about 13.6%for furan and 34.8%for epoxy.Also,porosity raised by about 21.8%for furan,and 19%for epoxy by brine injection.The results showed that the chemical sand consolidation weakens in the face of brine production along with crude oil which can lead to increasing cost of oil production and treating wellbore again.

Hubble Tension Explanation from This Cosmological Model AΛΩ (Slow Bang Model, SB)

In this article we present a model of Hubble-Lemaître law using the notions of a transmitter (galaxy) and a receiver (MW) coupled to a model of the universe (Slow Bang Model, SB), based on a quantum approach of the evolution of space-time as well as an equation of state that retains all the infinitesimal terms. We find an explanation of the Hubble tension H0. Indeed, we have seen that this constant depends on the transceiver pair which can vary from the lowest observable value, from photons of the CMB (theoretical [km/s/Mpc]) to increasingly higher values depending on the earlier origin of the formation of the observed galaxy or cluster (ETG ~0.3 [Gy], ~74 [km/s/Mpc]). We have produced a theoretical table of the values of the constant according to the possible pairs of transmitter/receiver in the case where these galaxies follow the Hubble flow without large disturbance. The calculated theoretical values of the constant are in the order of magnitude of all values mentioned in past studies. Subsequently, we applied the models to 9 galaxies and COMA cluster and found that the models predict acceptable values of their distances and Hubble constant since these galaxies mainly follow the Hubble flow rather than the effects of a galaxy cluster or a group of clusters. In conclusion, we affirm that this Hubble tension does not really exist and it is rather the understanding of the meaning of this constant that is questioned.

基于流体振荡器阵列的S型流道主动控制实验研究

本文针对一个典型的大折转角、大尺度S弯流道,设计并制造了一个由16个流体振荡器组成的大型阵列,并对S弯内部流动进行了主动控制实验研究。首先采用高频响热线风速仪、高精度质量流量计等手段测量了流体振荡器的频率、速度、流量等随进口压力的响应变化规律及其在大型阵列中的工作特性一致性。其次采用壁面压力采集、五孔探针等手段测量了不同激励条件下,S弯流道的壁面压力分布以及出口截面的总压分布情况。结果表明,所设计的脉冲型流体振荡器能够产生1 kHz以上,峰值速度高于300 m/s的高频高速振荡射流,且阵列中多个振荡器的流量、频率、振荡速度范围等工作特性保持了较好的一致性。流体振荡器阵列在S弯流道上壁面一弯前缘形成了一排开孔率仅为10%的脉冲射流孔,在与主流成45°射流角度、进口马赫数Ma=0.15,激励速度比uR=4.31条件下,仅使用激励质量流量比Cm=0.39%的激励质量流量,就使S弯流道的出口平均总压损失改善了10.6%。本研究验证了流体振荡器阵列控制大尺寸分离流动的高效能力。

胎盘生长因子联合脐动脉S/D值对子痫前期的预测价值

目的:探讨胎盘生长因子(PLGF)联合脐血流S/D对子痫前期的预测价值。方法:采用病例对照研究,回顾性选取2020年4月—2021年4月就诊于我院产科并最终诊断为子痫前期的孕产妇52例作为研究组,并选取同期正常分娩的产妇122例作为对照组,将孕期划分为三个阶段,孕早期(12~20周)、孕中期(20~34周)、孕晚期(34~42周),收集并分析两组孕妇早中晚期的胎盘生长因子(PLGF)、孕中晚期脐动脉收缩末期最大血流速度(S)与舒张末期最大血流速度(D)比值(S/D),评估PLGF、S/D值单独及联合预测子痫前期的效能。结果:研究组血清PLGF在妊娠各阶段平均值均明显低于对照组(P<0.05),研究组脐动脉S/D平均值高于对照组,孕中期两组间比较差异无统计学意义(P=0.21),孕晚期两组间比较差异有统计学意义(P=0.047),血清PLGF联合脐动脉S/D值在孕中期的特异度、灵敏度、AUC(ROC曲线下面积)分别为80.0%、63.6%、0.664,孕晚期的特异度、灵敏度、AUC分别为71.9%、81.8%、0.804。结论:研究组妊娠各个时期PLGF值均低于对照组,可以单独作为子痫前期患者的预测指标,S/D值单独预测价值与PLGF联合S/D值的预测价值在孕晚期优于孕中期,推测与纳入研究组患者的病情严重程度有关。

S Zorb装置转剂线腐蚀风险评估与磨损特性分析

催化裂化汽油吸附脱硫技术(S Zorb)是一种清洁汽油生产的核心技术,近年来,S Zorb装置中出现的转剂线磨损和泄漏等问题已成为石油化工行业内的共性难点问题。某公司2号S Zorb装置自2013年投用以来,转剂线频繁出现磨损和泄漏问题,以该案例为研究对象,对转剂线开展腐蚀风险评估以及气固两相流流态和磨损机理等综合特性分析,同时对弯管弯径比和气速对磨损的影响进行了讨论,为转剂线的设计优化以及运行可靠性的提升提供了参考。

脐动脉血流S/D值联合孕妇血清CX3CL1 HIF-1α对胎儿窘迫的诊断价值

目的探讨脐动脉血流收缩期末最大血流速度/舒张期末最大血流速度(S/D)、血清趋化因子C-X3-C配体1(CX3CL1)、血清缺氧诱导因子-1α(HIF-1α)对胎儿窘迫(FD)的诊断价值。方法选取2020年5月至2022年5月在青岛市妇女儿童医院妇产科分娩且出现FD的128例孕妇为研究对象(FD组),根据新生儿Apgar评分将FD孕妇分为轻度窘迫组74例和重度窘迫组54例,另取同期在本院定期产检并分娩的健康且未出现FD的孕妇78例为正常组;超声检测FD孕妇脐动脉血流S/D值;ELISA法检测FD孕妇血清CX3CL1、HIF-1α水平;Pearson法分析FD孕妇血清CX3CL1、HIF-1α水平与脐动脉血流S/D值的相关性;受试者工作特征(ROC)曲线分析血清CX3CL1、HIF-1α水平及脐动脉血流S/D值对胎儿重度窘迫的诊断价值。结果FD组孕妇脐动脉血流阻力指数(RI)、搏动指数(PI)、S/D值、血清CX3CL1及HIF-1α水平均显著高于正常组(P<0.05),重度窘迫组孕妇RI值、PI值、S/D值、血清CX3CL1及HIF-1α水平均高于轻度窘迫组(P<0.05)。FD组血清CX3CL1、HIF-1α与脐动脉血流S/D值均呈正相关(r=0.531、0.489,P<0.05)。脐动脉血流S/D值、血清CX3CL1、HIF-1α以及3项联合诊断胎儿重度窘迫的AUC分别为0.870、0.802、0.731、0.941,联合诊断的灵敏度为87.04%,特异度为90.54%,3项联合优于脐动脉血流S/D值、血清CX3CL1、HIF-1α各自单独诊断(Z3项联合-S/D=2.775、Z3项联合-CX3CL1=3.998、Z3项联合-HIF-1α=4.925,P均<0.05)。结论FD孕妇脐动脉血流S/D值、血清CX3CL1、HIF-1α水平均上升,且血清CX3CL1、HIF-1α水平与脐动脉血流S/D值均呈正相关,3项联合对诊断胎儿重度窘迫有更高的价值。

红细胞比容、血流S/D比值及同型半胱氨酸在妊娠期糖尿病患者中的表达及对妊娠结局的影响

目的探究红细胞比容、血流S/D比值及同型半胱氨酸在妊娠期糖尿病患者中的表达及对妊娠结局的影响。方法选取我院2021年1月~2023年1月纳入的86例妊娠期糖尿病患者为研究组,另外选取同时期86例妊娠期健康孕妇作为对照组,分别对两组孕妇以及研究组不同疾病严重程度孕妇之间的红细胞比容、血流S/D比值、同型半胱氨酸表达水平进行比较,观察记录两组孕妇不良妊娠结局的发生情况。结果研究组孕妇的红细胞比容明显低于对照组,血流S/D比值及同型半胱氨酸表达水平均明显高于对照组,差异有统计学意义(P<0.05);轻度、中度、重度妊娠期糖尿病患者的红细胞比容、血流S/D比值及同型半胱氨酸水平存在明显差异,且随着疾病严重程度的增高,红细胞比容越低,血流S/D比值及同型半胱氨酸水平越高,差异有统计学意义(P<0.05);研究组孕妇的不良妊娠结局总发生率明显高于对照组,差异有统计学意义(P<0.05)。结论红细胞比容、血流S/D比值及同型半胱氨酸在妊娠期糖尿病患者中的表达水平异于健康孕妇,同时还与孕妇的妊娠结局存在一定的关联,血流S/D比值及同型半胱氨酸较高水平的表达与红细胞比容较低的情况增加了妊娠期糖尿病孕妇不良妊娠结局的发生率。

Ramsay Hunt′s 29例临床分析

目的探讨RamsayHunt’s(RHS)的治疗方法、疗效。方法对29例患者临床资料回顾性分析。结果通过抗病毒、消除水肿等综合治疗,近期痊愈显效率达93.1%。结论早期识别和正规治疗是关键。

基于S-A模型的覆冰输电线绕流数值分析

基于Spalart-Allmaras湍流模型(S-A模型)封闭的雷诺平均N-S方程,采用沿均匀流线的三阶Runge-Kutta法和Galerkin法分别进行时间和空间离散,得到了湍流方程的有限元格式。采用自编Matlab程序,数值模拟了不同风攻角下覆冰输电线绕流问题,得到了覆冰输电线绕流瞬态和时均流场、气动力系数时程曲线和平均气动力系数随风攻角的变化关系,并与试验结果进行对比,验证了该算法的有效性。基于流场演化和平均压力分布,分析表明风攻角变化引起的边界层分离点转移是产生升力系数尖峰突跳现象的主要原因。

S翼型水力优化及非稳态绕流研究

为了揭示S翼型绕流性能提升的水力诱因,探索其水力性能与非稳态绕流特性间的内在关联,基于构造的自动寻优流程得到了水动力特性较优的新翼型,并利用LES方法和LDA试验探究了优化前、后S翼型的非稳态绕流特性及其差异。研究结果表明:优化翼型的最大升阻比为29,较原始翼型提升了30%,其对应最优攻角为8°,并大于OR翼型对应的6°攻角;优化后椭圆形的前缘可以有效地降低S翼型前缘处的表面摩擦系数;吸力侧流动分离现象的抑制可以显著优化S翼型的非稳态绕流结构,进而实现其水力性能的大幅提升。研究结果有助于为S翼型的水力设计提供理论指导,同时也可为双向轴流式水力机械提供水动力特性优异的S翼型。