Failure pressure calculation of fracturing well based on fluid-structure interaction

Failure pressure is a key parameter in reservoir hydrofracturing operation. Existing analytical methods for calculating the failure pressure are based on the assumption that borehole fluid is under two extreme conditions: non-infiltration or complete infiltration. The assumption is not suitable for the actual infiltration process, and this will cause a great error in practical calculation. It shows that during the injection process, the dynamic variation in effective stress-dependent permeability has an influence on the infiltration, and the influence also brings about calculation errors. Based on the fluid-structure interaction and finite element method (FEM), considering partial infiltration during injection process, a numerical model for calculating rock failure pressure is established. According to the analysis of permeability test results and response-surface method, a new variation rule of rock permeability with the change of effective stress is presented, and the relationships among the permeability, confining pressure and pore pressure are proposed. There are some differences between the dynamic value of permeability-effective-stress coefficient observed herein and the one obtained by the classical theory. Combining with the numerical model and the dynamic permeability, a coupling method for calculating failure pressure is developed. Comparison of field data and calculated values obtained by various methods shows that accurate values can be obtained by the coupling method. The coupling method can be widely applied to the calculation of failure pressure of reservoirs and complex wells to achieve effective fracturing operation.

Mechanical synergistic interaction between adjacent corrosion defects and its effect on pipeline failure

This work provides a new comprehensive assessment method to determine the complex mechanical interaction of adjacent corrosion defects.Firstly,a three-dimensional(3D)finite element model of pipelines containing adjacent defects(involving longitudinally aligned,circumferentially aligned,and diagonally aligned defects)was developed and validated by full-scale burst tests.Then,the synergistic stress interaction between adjacent defects was analyzed,and the relationship between the burst position of the pipeline and defect spacing was determined.At last,the applicability of several commonly used critical spacing rules for identifying the interaction between adjacent defects was compared and discussed in detail.The results show that the failure position of the pipeline containing adjacent defects is related to the relative position of defects.For longitudinally aligned corrosion defects,the stronger the interaction between defects(i.e.,the shorter the distance between two defects),the closer the failure position of the pipeline to the center of the defect spacing.For circumferentially aligned corrosion defects,the failure position of the pipe tends to move from the defect edge to the geometric center of the defect with increasing defect spacing.For diagonally aligned defects,the failure position is generally located on the path connecting the defect and the spacing.The currently available evaluation criteria for identifying circumferentially interacting defects display the most accuracy,and the identification effect of diagonally aligned defects is the poorest.In addition,the critical spacing rule proposed by Li presents the highest precision in identifying the interacting defects.The results are expected to provide a stress synergistic failure assessment method for pipelines containing cluster corrosion defects in engineering.

Drug-Drug Interactions in Patients with Breast Cancer

The research paper investigates the intricate landscape of drug-drug interactions (DDIs) within the context of breast cancer treatment, with a particular focus on the elderly population and the use of complementary and alternative medicine (CAM). The study underscores the heightened susceptibility of elderly patients to DDIs due to the prevalence of polypharmacy and the widespread utilization of CAM among breast cancer patients. The potential ramifications of DDIs, encompassing adverse drug events and diminished treatment efficacy, are elucidated. The paper accentuates the imperative for healthcare providers to comprehensively understand both conventional and CAM therapies, enabling them to provide patients with informed guidance regarding safe and efficacious treatment options, culminating in enhanced patient outcomes.

Study on Interaction Relationship for Submarine Pipeline with Axial Corrosion Defects

Corrosion is one of the main reasons to cause the operation accident of submarine oil and gas transmission pipelines. As the major corrosion pattern in submarine pipelines, the effects of corrosion clusters consisting of the adjacent corrosion defects on failure pressure are investigated through non-linear large-deformation finite element method. Typically, the failure behavior and limit strength of submarine pipeline with axial groove- groove corrosion defect pair exposed to interhal pressure are analyzed. The effects of corrosion depth and axial spacing between a pair of corrosion defects on failure pressure are concluded. An interaction relationship for corrosion defects in pipelines, as well as prediction formulations for assessing the remaining strength of corroded pipelines are proposed. The expressions based on the proposed interaction relationship give more accurate results than the methods used in the existing design guidelines.

Modeling pipe-soil interaction under vertical downward relative offset using B-spline material point method

To analyze the pipeline response under permanent ground deformation,the evolution of resistance acting on the pipe during the vertical downward offset is an essential ingredient.However,the efficient simulation of pipe penetration into soil is challenging for the conventional finite element(FE)method due to the large deformation of the surrounding soils.In this study,the B-spline material point method(MPM)is employed to investigate the pipe-soil interaction during the downward movement of rigid pipes buried in medium and dense sand.To describe the density-and stress-dependent behaviors of sand,the J2-deformation type model with state-dependent dilatancy is adopted.The effectiveness of the model is demonstrated by element tests and biaxial compression tests.Afterwards,the pipe penetration process is simulated,and the numerical outcomes are compared with the physical model tests.The effects of pipe size and burial depth are investigated with an emphasis on the mobilization of the soil resistance and the failure mechanisms.The simulation results indicate that the bearing capacity formulas given in the guidelines can provide essentially reasonable estimates for the ultimate force acting on buried pipes,and the recommended value of yield displacement may be underestimated to a certain extent.

Wave-ice dynamical interaction:a numerical model and its application

In this paper,an ice floe inner stress caused by the wave-induced bending moment is derived to estimate the stress failure of ice floe.The strain and stress failures are combined to establish a wave-induced ice yield scheme.We added ice stress and strain failure module in the Finite-Volume Community Ocean Model(FVCOM),which already includes module of ice-induced wave attenuation.Thus a fully coupled wave-ice dynamical interaction model is established based on the ice and wave modules of FVCOM.This model is applied to reproduce the ice and wave fields of the breakup events observed during the second Sea Ice Physics and Ecosystem Experiment(SIPEX-2)voyage.The simulation results show that by adopting the combined wave-induced ice yield scheme,the model can successfully predict the ice breakup events,which the strain failure model is unable to predict.By comparing the critical significant wave height deduced from strain and stress failure schemes,it is concluded that the ice breakup is caused by the strain failure when wave periods are shorter than a threshold value,while the stress failure is the main reason for the ice breakup when wave periods are longer than the threshold value.Neglecting either of these two ice-break inducement mechanisms could overestimate the ice floe size,and thus underestimate the velocity of the ice lateral melt and increase the error of simulation of polar ice extent.

Coulomb stress and gravity changes associated with the 2016 Mw 7.8 Kaikoura Earthquake, New Zealand: Application for aftershock triggering and fault interaction process analysis

The Kaikoura earthquake on November 14,2016 is one of the largest and most complex earthquakes in New Zealand since 1947.Despite the fact that it has ruptured about 12 separate faults,triggered 2132 aftershocks within one week of the mainshock and induced considerable stress changes,few studies have been conducted to comprensively investigate the characteristics.The current study examines the horizontal and vertical displacements as well as the stress and gravity changes,aftershock distributions and also find out whether these changes affect the surrounding regions along the complex fault systems.The study covers the entire area affected by the Kaikoura event,which includes the northern part of the South Island and the southern part of the North Island.The dislocation theory was employed to evaluate the coseismic slip model on the multiple faults.The displacement results revealed that the maximum horizontal displacement is about 6 m and the vertical about 2 m,which are reasonably consistent with earlier study findings.Besides,the stress and gravity changes are quite complicated and inhomogeneous as evidenced by our coseismic model,demonstrating the complexity of the Kaikoura earthquake as well.Almost all the aftershocks are distributed in places where the stress and gravity change are found to be significant.In order to investigate the stability of our stress change models,we applied different friction coefficients and receiver fault parameters.The results justify the friction coefficient(μ=0.4)and the receiver fault parameters(230°,70°,150°)are suitable to define good stress change estimates.According to the stress change results at 15 km depth,the northern parts of the mainshock region,Hundalee fault,Humps fault and Jordan thrust areas together with the Wellington area are closer to failure and situated in a seismic risk zone.The multidimensional analysis adopted in this paper is helpful for making decisions and applications of stress and gravity change models in assessing seismic hazards.

Service Failures in 3- to 5-Star Hotels in Accra, Ghana

This paper examines service failures in 3- to 5-star hotels in the Accra Metropolis in Ghana. The objectives of the research were to ascertain the categories of service failures commonly experienced by guests and assess guests＇ level of dissatisfaction with the service failures. Descriptive survey design using critical incident questionnaires （CIQ） was used to collect data from a purposive sample of 174 guests who experienced service failures in ten 3- to 5-star hotels. The data were analyzed using SPSS. The most dominant service failures experienced by guests were service system failures, such as unavailable/irregular service and defective products, occurring mostly in the housekeeping departments. With the revelation of potential service failures experienced by guests and their effect on guests, this study offers suggestions to managers to revamp some policies to curtail some service failures and improve service delivery. This study contributes to the literature on service failure in the context of a developing country.

Progressive failure processes of reinforced slopes based on general particle dynamic method

In order to resolve grid distortions in finite element method(FEM), the meshless numerical method which is called general particle dynamics(GPD) was presented to simulate the large deformation and failure of geomaterials. The Mohr-Coulomb strength criterion was implemented into the code to describe the elasto-brittle behaviours of geomaterials while the solid-structure(reinforcing pile) interaction was simulated as an elasto-brittle material. The Weibull statistical approach was applied to describing the heterogeneity of geomaterials. As an application of general particle dynamics to slopes, the interaction between the slopes and the reinforcing pile was modelled. The contact between the geomaterials and the reinforcing pile was modelled by using the coupling condition associated with a Lennard-Jones repulsive force. The safety factor, corresponding to the minimum shear strength reduction factor "R", was obtained, and the slip surface of the slope was determined. The numerical results are in good agreement with those obtained from limit equilibrium method and finite element method. It indicates that the proposed geomaterial-structure interaction algorithm works well in the GPD framework.

Predicting heartbeat arrival time for failure detection over internet using auto-regressive exogenous model

Predicting heartbeat message arrival time is crucial for the quality of failure detection service over intemet. However, intemet dynamic characteristics make it very difficult to understand message behavior and accurately predict heartbeat arrival time. To solve this problem, a novel black-box model is proposed to predict the next heartbeat arrival time. Heartbeat arrival time is modeled as auto-regressive process, heartbeat sending time is modeled as exogenous variable, the model＇ s coefficients are estimated based on the sliding window of observations and this result is used to predict the next heartbeat arrival time. Simulation shows that this adaptive auto-regressive exogenous （ARX） model can accurately capture heartbeat arrival dynamics and minimize prediction error in different network environments.

交互失误情境下交互式人工智能拟人化的负面影响——基于ChatGPT和搜索引擎的实验证据

[目的/意义]对人机交互失误情境下用户产生的情绪和态度展开研究,旨在验证人工智能拟人化理论的负面效应并探索交互式人工智能拟人化产生负面影响的缓解机制。[方法/过程]以人机交互失误为情境,基于期望一致性理论和拟人化理论,通过实验法分别从交互的结果失误和调用失误两个角度,探索了交互式人工智能不同的拟人化程度对用户产生负面态度的影响机制。[结果/结论]研究发现,人机交互失误时,高拟人化的交互式人工智能会加剧用户对其的厌恶感和负面态度。验证了算法可解释性能够缓解厌恶感和负面态度。综合上述分析,从人机交互健康长远发展角度,提出了人工智能应采用有限拟人化的设计框架和具有可解释性的算法架构等建议。

三维动静加载下煤的本构模型及卸荷破坏特征

为研究非静水压条件下煤体动力学性能及动力扰动后卸荷破坏特征,在三维动静加载实验的基础上,研究了卸荷方式对动力扰动后卸荷煤样宏观破坏特性的影响。首先,采用Ф50 mm的分离式霍普金森压杆系统,开展三维动静加载下煤样的动力学实验,研究轴压、应变率对煤样动力学响应规律的影响;其次,基于响应曲面理论,借助中心复合试验法,构建考虑因素交互作用的回归模型,并分析单因素及因素交互作用的显著性;然后,结合因素交互作用、Weibull分布、Drucker-Prager准则,修正煤的强度型统计损伤本构模型,对比理论与实验结果,验证模型可靠性;最后,借助加卸荷电液伺服装置,探究轴压、冲击气压、卸荷方式对煤样破坏特征的影响及作用机制。结果表明,构建的强度型统计损伤模型,相关系数R~2≥0.88,可表征煤样动力学响应行为。冲击后同步卸荷的煤样多呈层裂破坏,拉伸界面随轴压增大而后移直至消失,无法形成层裂破坏;非同步卸荷下煤样破坏形式主要包括整体完整、层裂、压剪破坏,而当冲击气压0.4~0.6 MPa,轴压14.5 MPa时,表现为“层裂+压剪”混合破坏。

动态心电图与血清FOXO3、TXNIP蛋白水平对慢性心力衰竭的诊断价值

目的 探讨叉头转录蛋白O亚族3(FOXO3)、硫氧还蛋白相互作用蛋白(TXNIP)在慢性心力衰竭患者血清中的表达及联合动态心电图检查对慢性心力衰竭的诊断价值。方法 前瞻性选取2022年6月至2023年1月期间于湖北省鄂州市中心医院收治的68例慢性心力衰竭患者作为心力衰竭组,另选取68例同期门诊健康体检者为对照组。比较两组血清FOXO3,TXNIP蛋白水平;ROC曲线分析血清FOXO3、TXNIP对慢性心力衰竭的诊断效能;四表格法分析动态心电图联合血清FOXO3,TXNIP对慢性心力衰竭的诊断效能。结果 心力衰竭组血清FOXO3蛋白表达水平为(1.28±0.34)ng/ml低于对照组(1.73±0.36)ng/ml(P<0.05),TXNIP蛋白表达水平为(126.42±12.98)pg/ml高于对照组(108.86±12.73)pg/ml,差异有统计学意义(P<0.05)。动态心电图联合血清FOXO3,TXNIP诊断慢性心力衰竭的准确率为94.85%,敏感性为97.06%,特异性为92.65%;三项联合诊断的准确率和敏感性均高于单独诊断(P<0.05)。结论 慢性心力衰竭患者血清FOXO3表达水平降低,TXNIP表达水平升高,动态心电图联合血清FOXO3,TXNIP蛋白水平对慢性心力衰竭具有较高的诊断价值。

复合磨损套管爆裂失效机理及剩余强度预测

超深井、水平井、大位移井等复杂油气井服役工况异常恶劣,套管复合磨损严重,将对井筒完整性构成巨大威胁,且磨损套管剩余强度难以精准预测。为此,基于塔里木盆地塔中北坡顺南区块501井套管磨损数据及P110管材应力—应变本构关系,建立了充分考虑钻杆本体和接头联合造成的磨损模式、夹角、磨损重叠深度及磨损深度的复合磨损套管有限元力学模型,并开展了多种复合磨损模式下套管弹塑性变形、屈服、裂纹萌生、扩展及爆裂行为模拟,得到了不同复合磨损套管应力分布、剩余抗内压屈服强度及爆裂强度。研究结果表明:(1)月牙夹角在0°~90°时,应力干涉削弱应力集中,月牙夹角在90°~180°时,应力干涉增强应力集中,这种交互作用机制导致磨损套管剩余强度随着月牙夹角增加而先增加后降低;(2)裂纹萌生并起始于等效应力最大的位置即磨损月牙中心,并垂直于最大环向应力沿径向从套管内壁向外壁扩展,且裂纹一旦萌生,裂纹将迅速扩展并发生爆裂失效;(3)灰色关联度分析确定了复合磨损套管剩余强度对磨损深度、月牙夹角、复合磨损形式、月牙重叠深度的敏感性,分析结果表明磨损深度是决定套管剩余强度的主控因素。结论认为,该认识为套管强度设计与优化提供了技术参考,并对准确预测复合磨损套管剩余强度和确保井筒安全及完整性具有重要意义。

TNIP1基因单核苷酸多态性及其mRNA表达水平与老年慢性心力衰竭患者肺部感染的相关性分析

目的探讨肿瘤坏死因子诱导蛋白3相互作用蛋白1(TNFAIP3-interacting protein 1,TNIP1)基因单核苷酸多态性及其mRNA表达水平与老年慢性心力衰竭患者肺部感染的相关性。方法选择2019年10月至2022年10月于上海建工医院重症医学科就诊的130例老年慢性心力衰竭患者作为研究对象,根据是否于院内发生肺部感染分为感染组(32例)和未感染组(98例)。对TNIP1基因的两个SNP位点rs6889239(T>C)、rs17728338(A>G)进行基因分型,并检测外周血TNIP1基因的mRNA表达水平。结果TNIP1基因rs6889239位点在感染组和非感染组之间的基因型分布以及等位基因频率的差异均无统计学意义(P>0.05);两组的rs17728338位点AA、AG、GG基因型分布比较差异有统计学意义(P<0.05),且感染组等位基因G的频率显著高于未感染组(P<0.05)。相较于未感染组,感染组患者的外周血TNIP1基因mRNA表达水平显著增加,差异有统计学意义(P<0.001)。受试者工作特征(Receiver operating characteristic,ROC)曲线分析结果显示外周血TNIP1基因表达水平预测慢性心力衰竭患者发生肺部感染的灵敏度和特异度分别为71.9%和95.9%。感染组和非感染组TNIP1基因rs6889239位点不同基因型患者的外周血TNIP1基因的表达水平比较差异均无统计学意义(P>0.05),而rs17728338位点不同基因型患者的外周血TNIP1基因表达水平比较差异有统计学意义(P<0.05)。结论TNIP1基因rs17728338表达水平与老年慢性心力衰竭患者发生肺部感染有关。

多馈入直流输电系统后续换相失败安全裕度评估及抑制方法

换相失败可能引起直流输电系统(line commutated converter based high voltage direct current,LCC-HVDC)闭锁,严重影响电网的安全稳定运行。多馈入直流输电系统中电气耦合紧密,控制响应造成多回LCC-HVDC交互影响,使换相失败的产生机理变得更加复杂。现有后续换相失败抑制方法多以单回LCC-HVDC为对象,无法兼顾自身换相恢复和相邻直流换相失败抑制的需求。为此,提出了一种适应于多馈入直流输电系统的后续换相失败抑制方法。分析了LCC-HVDC首次换相失败恢复过程中逆变站控制系统的响应时序及条件,提出了考虑故障严重程度和LCC-HVDC控制影响的后续换相失败安全裕度评估方法,进而提出了基于电压安全裕度的后续换相失败抑制方法,并在CIGRE HVDC标准测试系统验证了所提方法的有效性。仿真结果表明,所提方法根据换流母线电压自适应地调节直流电流,能够有效降低多馈入直流输电系统中无功电压耦合影响,有效抑制相邻回LCC-HVDC发生后续换相失败。

基于故障物理的风力机叶片可靠性仿真分析方法

提出一种基于故障物理的风力机叶片可靠性仿真分析方法,通过绘制任务剖面和载荷剖面图,将叶片材料、结构、环境条件和使用方式等参数加载到数值计算模型中,进行瞬态热力学、振动应力和多应力耦合分析。结果表明,最大应力和热集中主要发生在叶片根部,变形主要发生在叶片中部到叶尖这段区间。从故障原因和机理出发研究叶片的故障规律,运用FMECA(故障模式、影响和危害性分析)处理收集到的故障信息。将定性评价指标予以定量化,以此建立叶片危害性矩阵和FMECA表格,在失效模式下对高危性故障数据进行可靠性评估,为工程实际提供必要的理论支持。该方法相较于传统基于手册的可靠性分析方法精度更高,与研制、生产、维修和管理并行,通过不断更新迭代,以保证产品可靠性要求的实现,为风力机叶片的可靠性分析提供了新的思路和实施方法。

基于FMEA和RCA的适老化智能家电产品交互设计研究

目的为了进行智能家电产品的适老化升级,提升老年人的用户体验。方法提出基于失效模式与效应分析(FMEA)和根本原因分析(RCA)的适老化智能家电产品交互设计方法。首先,通过构建老年人使用智能家电的用户旅程图识别失效模式,利用FMEA对失效模式进行分析并评估风险优先指数;其次,根据风险优先指数绘制帕累托图确定重点失效模式,并运用石川图分析其发生的根本原因;再次,围绕根本原因对智能家电产品交互设计进行改良;最后,对改良后的设计进行测试并评估改良效果。结论选取智能洗衣机作为案例进行研究,结果表明所提出方法能够有效识别老年人使用智能家电时发生的失效模式,并对其发生的根本原因进行分析,可为适老化智能家电产品的设计优化提供方法参考,帮助老年人享受技术红利,跨越数字鸿沟。

Proper interpretation of sectional analysis results

Displacement control algorithms commonly used to evaluate axial force-bending moment(PM)diagrams may lead to incorrect interpretations of the strength envelopes for asymmetric sections.This paper aims to offer valuable insights by comparing existing displacement control algorithms with a newly proposed force control algorithm.The main focus is on the PM diagrams of three example sections that exhibit varying degrees of asymmetry.The comparative study indicates that conventional displacement control algorithms inevitably introduce non-zero out-of-plane bending moments.The reported PM diagram in such cases erroneously neglects the out-of-plane moment and fails to represent the strength envelope accurately.This oversight results in significant and unconservative errors when verifying the strength of asymmetric sections.

RIPK3在LPS/D-GalN诱导急性肝衰竭中的作用研究

目的研究受体相互作用蛋白激酶3(receptor-interacting protein kinases 3,RIPK3)在脂多糖(lipopolysaccharide,LPS)/D-氨基半乳糖(D-galactosamine,D-GalN)诱导的急性肝衰竭(acute liver failure,ALF)中的作用。方法体内实验使用SPF级雄性BALB/c小鼠15只,随机分为对照组(Control),模型组(LPS/D-GalN),抑制剂预处理组(GSK872+LPS/D-GalN),每组5只。ALF动物模型采用LPS联合D-GalN腹腔注射的方式制备。药物腹腔注射前1 h,分别以0.1%DMSO和RIPK3特异性拮抗剂GSK872(溶于0.1%DMSO)尾静脉注射进行预处理。肝损伤程度采用血生化检测和肝脏组织学变化来评估;基因mRNA表达采用PCR检测,蛋白表达采用蛋白质印迹和免疫组化分析。结果动物实验结果显示,与正常对照组(Control)相比,模型组(LPS/D-GalN)小鼠肝组织见显著炎症出血坏死性损伤,肝内F4/80+细胞浸润增多,血清ALT和AST水平明显升高(P_(均)<0.01)。同时,肝组织F4/80、Mcp-1、Tnf-α、Il-6、Ripk3和Mlkl mRNA,以及RIPK3蛋白和p-MLKL/MLKL蛋白比值均上调,差异均存在统计学意义(P_(均)<0.05)。与模型组相比,预处理组(GSK872+LPS/D-GalN)小鼠肝脏炎症损伤程度明显减轻,肝内F4/80+细胞浸润明显减少,且血清ALT和AST水平显著下降(P_(均)<0.01)。肝组织F4/80、Mcp-1、Tnf-α、Il-6、Ripk3和Mlkl mRNA,以及RIPK3蛋白和p-MLKL/MLKL蛋白比值下调,差异均有统计学意义(P_(均)<0.05)。结论在LPS/D-GalN联合诱导的小鼠急性肝衰竭模型中,RIPK3抑制剂的应用可能直接通过靶向肝细胞,减少肝细胞的坏死性凋亡,从而减少巨噬细胞浸润,最终改善肝脏炎症状态。这提示RIPK3可能通过对肝细胞坏死性凋亡通路分子的影响促进ALF的发生和发展。