Simulation of Corrosion-Induced Cracking of Reinforced Concrete Based on Fracture Phase Field Method

Accurate simulation of the cracking process caused by rust expansion of reinforced concrete(RC)structures plays an intuitive role in revealing the corrosion-induced failure mechanism.Considering the quasi-brittle fracture of concrete,the fracture phase field driven by the compressive-shear term is constructed and added to the traditional brittle fracture phase field model.The rationality of the proposed model is verified by a mixed fracture example under a shear displacement load.Then,the extended fracture phase model is applied to simulate the corrosion-induced cracking process of RC.The cracking patterns caused by non-uniform corrosion expansion are discussed for RC specimens with homogeneous macroscopically or heterogeneous with different polygonal aggregate distributions at the mesoscopic scale.Then,the effects of the protective layer on the crack propagation trajectory and cracking resistance are investigated,illustrating that the cracking angle and cracking resistance increase with the increase of the protective layer thickness,consistent with the experimental observation.Finally,the corrosion-induced cracking process of concrete specimens with large and small spacing rebars is simulated,and the interaction of multiple corrosion cracking is easily influenced by the reinforcement spacing,which increases with the decrease of the steel bar interval.These conclusions play an important role in the design of engineering anti-corrosion measures.The fracture phase field model can provide strong support for the life assessment of RC structures.

A Coupled Thermomechanical Crack Propagation Behavior of Brittle Materials by Peridynamic Differential Operator

This study proposes a comprehensive,coupled thermomechanical model that replaces local spatial derivatives in classical differential thermomechanical equations with nonlocal integral forms derived from the peridynamic differential operator(PDDO),eliminating the need for calibration procedures.The model employs a multi-rate explicit time integration scheme to handle varying time scales in multi-physics systems.Through simulations conducted on granite and ceramic materials,this model demonstrates its effectiveness.It successfully simulates thermal damage behavior in granite arising from incompatible mineral expansion and accurately calculates thermal crack propagation in ceramic slabs during quenching.To account for material heterogeneity,the model utilizes the Shuffle algorithm andWeibull distribution,yielding results that align with numerical simulations and experimental observations.This coupled thermomechanical model shows great promise for analyzing intricate thermomechanical phenomena in brittle materials.

Evaluation of Clinical Efficacy of Wumen Acupuncture in the Adju-vant Treatment of Non-arteriticAnterior Ischemic Optic Neuropathy

[Objectives]To explore the clinical efficacy of Wumen acupuncture in the adjuvant treatment of non-arteritic anterior ischemic op-tic neuropathy(NAION).[Methods]From June 2023 to April 2024,40 NAION patients were randomly divided into treatment group(Wu-men acupuncture method+methylprednisolone sodium succinate+compound Danshen dripping pills orally)and control group(methylpred-nisolone sodium succinate+compound Danshen dripping pills orally).The clinical symptoms such as fundus condition and visual field were compared between the two groups before treatment,after 2 courses of treatment and 6 months after the first diagnosis.[Results](i)After 2 courses of treatment,the patients with optic disc edema in the treatment group were more than those in the control group,and the difference was significant(P<0.05).The number of patients with retinal hemorrhage in the treatment group was less than that in the control group,and the difference was significant(P<0.05).The color of the optic nerve in the treatment group was less than that in the control group,and the difference was not significant(P>0.05).(ii)Six months after the first diagnosis,the improvement of fundus in the treatment group was bet-ter than that in the control group(P<0.05).After 2 courses of treatment and 6 months after the first diagnosis,the visual evoked potential was significantly improved compared with the control group(P<0.05).After 2 courses of treatment and 6 months from the first diagnosis,the number of lines of visual acuity improvement in the treatment group was greater than that in the controlgroup(P<0.05).After 2 courses of treatment and 6 months from the first diagnosis,the average visual field defect in the treatment group was lower than that in the control group(P<0.05).[Conclusions]Wumen acupuncture method can significantly improve the symptoms of patients with non-arteritic anterior ische-mic optic neuropathy,which is worthy of clinical promotion.

Pedestrian evacuation simulation in multi-exit case:An emotion and group dual-driven method

This paper analyzes the characteristics of emotion state and group behavior in the evacuation process.During the emergency evacuation,emotion state and group behavior are interacting with each other,and indivisible.The emotion spread model with the effect of group behavior,and the leader-follower model with the effect of emotion state are proposed.On this basis,exit choice strategies with the effect of emotion state and group behavior are proposed.Fusing emotion spread model,leader-follower model,and exit choice strategies into a cellular automata(CA)-based pedestrian simulation model,we simulate the evacuation process in a multi-exit case.Simulation results indicate that panic emotion and group behavior are two negative influence factors for pedestrian evacuation.Compared with panic emotion or group behavior only,pedestrian evacuation efficiency with the effects of both is lower.

Engineered nitrogen doping on VO_(2)(B)enables fast and reversible zinc-ion storage capability for aqueous zinc-ion batteries

Vanadium-based compounds with high theoretical capacities and relatively stable crystal structures are potential cathodes for aqueous zinc-ion batteries(AZIBs).Nevertheless,their low electronic conductivity and sluggish zinc-ion diffusion kinetics in the crystal lattice are greatly obstructing their practical application.Herein,a general and simple nitrogen doping strategy is proposed to construct nitrogen-doped VO_(2)(B)nanobelts(denoted as VO_(2)-N)by the ammonia heat treatment.Compared with pure VO_(2)(B),VO_(2)-N shows an expanded lattice,reduced grain size,and disordered structure,which facilitates ion transport,provides additional ion storage sites,and improves structural durability,thus presenting much-enhanced zinc-ion storage performance.Density functional theory calculations demonstrate that nitrogen doping in VO_(2)(B)improves its electronic properties and reduces the zinc-ion diffusion barrier.The optimal VO_(2)-N400 electrode exhibits a high specific capacity of 373.7 mA h g^(-1)after 100 cycles at 0.1 A g^(-1)and stable cycling performance after 2000 cycles at 5 A g^(-1).The zinc-ion storage mechanism of VO_(2)-N is identified as a typical intercalation/de-intercalation process.

An Early Minor-Fault Diagnosis Method for Lithium-Ion Battery Packs Based on Unsupervised Learning

Dear Editor,Any fault of a battery system that is not handled timely can cause catastrophic consequences.Therefore,it is significant to diagnose battery faults early and accurately.Due to the complex nonlinear features and inconsistency of lithium batteries,traditional fault diagnosis methods usually fail to detect battery minor faults in the early stages.

零碳及碳中和燃料内燃机应用进展

随着交通领域日益增长的能源需求,气候变化以及能源安全问题不断凸显,发展可再生燃料受到关注.氢和氨的生产来源广泛,本身不含碳,在未来的脱碳进程中将会扮演重要角色.各类醇、醚和生物燃料可通过合成捕集的二氧化碳和氢气及利用生物材料获得,是实现碳中和的有效途径,其本身具有类似于汽油或柴油的燃烧特性.回顾了各类替代燃料在点燃式(spark ignition,SI)和压燃式(compression ignition,CI)内燃机中的应用,并分析了它们对发动机性能及排放特性的影响.零碳燃料氢气具有良好的燃烧特性,单独使用可以实现零碳排放,作为添加剂可以促进主燃料的燃烧,降低碳排放.零碳燃料氨的抗爆性能优良,可与氢气混合使用,但需要考虑较高的氮氧化物(NO;)排放.碳中和燃料能够单独在发动机中使用,也可与零碳燃料氢气混合使用,实现发动机高效、低排放.

社会流动感知和预期如何影响居民幸福感?——公共服务满意度的中介作用和社会公平感的调节作用

民众幸福感的提升,不仅源于经济流动(即相对收入的提高),还源于社会流动(即社会地位的改善)。基于2015年中国综合社会调查(CGSS)数据,采用Bootstrap方法检验社会流动感知和预期对居民幸福感的作用机制,研究发现,社会流动感知和社会流动预期均对居民幸福感存在正向影响;公共服务满意度在社会流动预期与幸福感之间具有遮掩效应,在社会流动感知与居民幸福感之间具有中介效应;社会公平感在社会流动感知与幸福感之间、社会流动预期与幸福感之间、社会流动预期与公共服务满意度之间,均发挥着调节作用。该研究不仅揭示了社会流动感知和预期对幸福感的作用机制,还具有新的公共政策价值,即社会政策的目标定位可从弱势群体向非弱势群体拓展,回应社会流动高预期人群对公共服务治理(尤其是公平性)的关切,从而带来提升民众幸福感和获得感之效。

国家监测能力的建构与提升——公共卫生危机背景下的反思

国家的监测能力既是国家能力的重要组成部分之一,也是公共治理体系的核心构成要素之一。国家监测能力有助于确保政府充分了解社会运行情况,作为其决策和政策执行的依据。新冠肺炎疫情对国家治理能力提出了巨大挑战,而国家监测能力的建构和提升对于危机管理的实施和绩效,具有重要意义。世界各国各地在实施某些疫情防控措施上的差异化表现,在一定程度上缘于其国家监测能力的差异。在对国家监测能力提升所带来的伦理、政治和社会问题予以关注并预警的同时,如何完善治理体系,提升治理能力,充分挖掘技术赋能的积极作用,尤其是在公共卫生危机应急管理中的应用,依然是公共管理学界亟待发展的研究领域。

基于1-DCNN-LSTM的滚动轴承自适应故障诊断方法研究

针对滚动轴承故障振动信号的非线性和非平稳特征,提出了一种自适应的一维卷积神经网络(1-Dimensional Convolutional Neutral Networks,1-DCNN)和长短期记忆网络(Long Short-Term Memory,LSTM)融合的轴承故障诊断方法。首先,将原始一维振动信号通过有重叠取样的方式分别输入1-DCNN和LSTM两个通道,然后通过Concatenate层进行空间和时间维度上特征信息的融合,最后,通过Softmax分类器进行故障类别的分类输出。该方法可以直接从原始振动信号中自适应提取特征,实现了"端到端"的故障诊断。采用CTU-2实验平台故障数据,通过对滚动轴承的不同故障类型、不同传感器采集方位、不同故障直径进行实验分析,结果表明:该方法在识别轴承故障类别上与其他方法相比具有更高的识别精度,并具有良好的有效性和稳定性。

中国政府创新与公共治理变革:文献综述和理论探索

政府创新及其引发的政策创新不仅是中国新时代改革与开放的重大实践问题,而且也是公共管理学的重大理论问题。论文围绕政府创新的研究概况、内涵外延、行动层级、行动类型、政策领域和理论建构等议题,对1990—2021年间发表的584篇关于中国政府创新的中英文文献进行了系统性的回顾,并探索其理论意涵。研究发现:(1)研究取向和方法有所偏倾,以规范研究和定性研究为主。(2)政府创新定义相对模糊,在行动类型上偏重风险性小的渐进型创新。(3)注重市级创新,不大重视基层创新,也相对忽视省级、国家级和跨国的重大创新。(4)政策领域较为单一,忽视了跨领域的变革力量。(5)理论探索虽有一些成果,但对治理变革的理论缺乏贡献。基于此,论文提出,未来中国政府创新研究的深化,除了在取向和方法上发展多样性之外,还应引入创新经济学中“创造性破坏”思想和治理理论前沿的协作/互动治理视角,进一步挖掘和归纳中国实践对公共治理变革的意涵,讲好政府创新的中国故事,为国际学界业已出现的“协作性政府创新”理论的拓展做出应有的贡献。

专栏导语:医疗卫生健康治理现代化的挑战与解决路径

医疗卫生健康事业如何达致善治(Good Governance),对于任何一个国家和地区的公共治理体系现代化来说,都是一项异常严峻的挑战。这一挑战的严峻性之所以异乎寻常,远甚于其他公共服务的治理,缘于医疗卫生健康服务具有高度多样性、多维性和多层性以及治理机制的嵌入性三大特征。

供方竞争的强化能否抑制中国医疗费用的上涨?--基于省级面板数据的实证分析

医疗供给侧供方竞争的强化对医疗费用的水平有何影响,在卫生经济学、产业组织经济学和医疗政策研究领域中一向是有争议的。基于传统的经济学原理,既有文献中存在着"竞争降费命题",但另有不少文献发现了反命题,即供方竞争的强化反而会推高医疗费用的宏观水平。论文基于2002—2016年中国省级面板数据进行计量分析,发现了两个貌似矛盾的现象:第一,医院密度的提高确有降费之效;第二,市场集中度提高(即大医院的兴起)也有降费之效。第一个现象确证了竞争降费命题,而第二个现象表面上看与竞争降费命题相悖,但实际上并非如此。大医院兴起的降费之效,是由一系列结构和制度性因素联合作用的结果。由此可以推测,在现阶段,中国新医改中两项貌似方向相反的举措,即提升供方竞争强度和推进医联体建设,都能产生一定的控费之效。

Two-level percutaneous endoscopic lumbar discectomy for highly migrated upper lumbar disc herniation: A case report

BACKGROUND The technique of percutaneous endoscopic lumbar discectomy(PELD)as a transforaminal approach has been used to treat highly migrated lower lumbar disc herniations.However,due to the different anatomic characteristics of the upper lumbar spine,conventional transforaminal PELD may fail to remove the highly migrated upper lumbar disc nucleus pulposus.Therefore,the purpose of this study was to describe a novel surgical technique,two-level PELD,for the treatment of highly migrated upper lumbar disc herniations and to report its related clinical outcomes.CASE SUMMARY A 60-year-old male presented with a complaint of pain at his lower back and right lower limb.The patient received 3 mo of conservative treatments but the symptoms were not alleviated.Physical examination revealed a positive femoral nerve stretch test and a negative straight leg raise test for the right leg,and preoperative visual analog scale(VAS)score for the lower back was 6 points and for the right leg was 8 points.Magnetic resonance imaging(MRI)demonstrated L2-L3 disc herniation on the right side and the herniated nucleus pulposus migrated to the upper margin of L2 vertebral body.According to physical examination and imaging findings,surgery was the primary consideration.Therefore,the patient underwent surgical treatment with two-level PELD.The pain symptom was relieved and the VAS score for back and thigh pain was one point postoperatively.The patient was asymptomatic and follow-up MRI scan 1 year after operation revealed no residual nucleus pulposus.CONCLUSION Two-level PELD as a transforaminal approach can be a safe and effective procedure for highly migrated upper lumbar disc herniation.

Construction of Ad-EGFP-BDNF vector and its expression in neural stem cells

BACKGROUND： Brain-derived neurotrophic factor （BDNF） provides nourishment to injured neurons. Neural stem cells can differentiate into neurons to repair neuronal injury in vivo. It has been hypothesized that continuous secretion of BDNF from neural stem cells could benefit brain injury repair. OBJECTIVE： To transfect BDNF and enhanced green fluorescent protein （EGFP） into neural stem cells with adenovirus vector and to observe expression of BDNF and EGFP in transfected neural stem cells. DESIGN, TIME AND SETTING： Observational, cellular, molecular study was performed at the Biochemistry Laboratory, Tongji University School of Medicine, China from July 2004 to September 2006. MATERIALS： Neural stem cells were provided by the Anatomy and Histoembryology Laboratory of Fudan University Medical School, China. METHODS： BDNF cDNA was extracted by reverse transcription polymerase chain reaction from the rat hippocampus. Following gene cloning and packaging by HEK293.BDNF, the EGFP gene was transfected into cultured neural stem cells with the Ad-EGFP-BDNF vector. BDNF-expressing neural stem cell clones were selected by G418 selection. MAIN OUTCOME MEASURES： EGFP expression and cell morphology were observed by fluorescent microscopy; neural stem cell expressing BDNF mRNA was examined by reverse transcription polymerase chain reaction; BDNF expression was detected by enzyme-linked immunosorbent assay from supematant of infected neural stem cells. RESULTS： High transfection efficiency was obtained using 5×10^8 virus titers to transfect neural stem cells. G418-resistant neural stem cell clones integrated BDNF mRNA fragments. Enzyme-linked immunosorbent assay results showed that BDNF expression in the supernatant increased with increasing culture time and peaked at 72 hours. CONCLUSION： Adenovirus-mediated BDNF and EGFP genes were successfully transfected into neural stem cells and were expressed in neural stem cells for a long period of time.

专栏导语:公共管理学术研究的“新冠”大考

新冠疫情对世界各地的国家治理体系都是一种考验。3月10日,国家主席习近平专程赴湖北省武汉市考察新冠肺炎疫情防控工作并发表重要讲话,明确指出,“这次新冠肺炎疫情防控,是对治理体系和治理能力的一次大考,既有经验,也有教训”(习近平,2020)。由此延伸,全球性爆发的新冠疫情已经成为对社会科学所有领域既有学问的一次大考,也为公共管理学界重新考察公共治理体系建设和治理能力的提升,提供了一个机会。

Reliability Analysis of Slope Stability Considering Temporal Variations of Rock Mass Properties

Temporal variation of rock mass properties,especially the strength degradation due to drying-wetting cycles as well as the acidic wetting fluid(rainfall or reservoir water)is crucial to stability of reservoir rock slopes.Based on a series of drying-wetting cycling and experiments considering the influences of pH values,the degradation degree models of the reduced cohesion𝑐𝑐′,friction angle𝜑𝜑′are developed.2D stability analysis of the slope is subsequently carried out to calculate the factor of safety(Fs)via limit equilibrium method(LEM)and a predictive model of Fs is built using multivariate adaptive regression splines(MARS),revealing the effect of the drying-wetting cycles and pH value.The reliability analysis by Monte Carlo simulation is performed to rationally consider the uncertainty and the temporal variation of the shear strength parameters of rock mass.Results indicate that the MARS-based model can estimate the Fs accurately.The Fs and the reliability indexβdecrease with increase of drying-wetting cycles,and the temporal variation of rock mass properties has significant influence on the slope reliability.Overlooking the temporal variation of rock properties may overestimate the Fs and reliability indexβin the longer term.

Laboratory Model Tests and DEM Simulations of Unloading-Induced Tunnel Failure Mechanism

Tunnel excavation is a complicated loading-unloading-reloading process characterized by decreased radial stresses and increased axial stresses.An approach that considers only loading,is generally used in tunnel model testing.However,this approach is incapable of characterizing the unloading effects induced by excavation on surrounding rocks and hence presents radial and tangential stress paths during the failure process that are different from the actual stress state of tunnels.This paper carried out a comparative analysis using laboratory model testing and particle flow code(PFC2D)-based numerical simulation,and shed light upon the crack propagation process and,microscopic stress and force chain variations during the loading-unloading process.The failure mode observed in the unloading model test is shear failure.The force chains are strongly correlated with the concrete fracture propagation.In addition,the change patterns of the radial and tangential stresses of surrounding rocks in the broken region,as well as the influence of the initial stress on failure loads are revealed.The surrounding soil of tunnel failure evolution as well as extent and shape of the damage zone during the excavation-induced unloading were also studied.

p75 NTR受体在视网膜色素上皮细胞氧化损伤中的作用及机制

目的:研究p75 NTR受体在视网膜色素上皮细胞(retinal pigment epithelial cells,RPE)氧化损伤过程中的作用及机制。方法:将转染p75 NTR受体的RPE细胞作为实验组,未转染的RPE细胞作为对照组。Brd U检测法检测细胞增殖活性;PI/Annexin V-FITC双染法检测细胞凋亡率;激光显微镜观察细胞内ROS的表达情况;流式细胞仪检测细胞内ROS、线粒体标志物、细胞色素C表达水平;Western blot法检测细胞中Fas蛋白、裂解Caspase-3、VEGF165蛋白的表达水平。结果:随着p75 NTR受体转染时间的延长,实验组RPE细胞的增殖活性呈逐渐降低趋势,各转染时间点的RPE细胞增殖活性比较,差异有统计学意义(P<0.05);实验组各转染时间点的RPE细胞增殖活性均明显低于对照组,差异均有统计学意义(P<0.05)。随着转染时间的延长,实验组RPE细胞凋亡率呈逐渐增加趋势,各转染时间点的RPE细胞凋亡率比较,差异有统计学意义(P<0.01);实验组各转染时间点的RPE细胞凋亡率均明显高于对照组,差异均有统计学意义(P<0.01)。实验组ROS荧光信号明显强于对照组。流式细胞仪检测结果显示,实验组RPE细胞中ROS、细胞色素C水平均明显高于对照组,线粒体标志物水平明显低于对照组,差异均有统计学意义(P<0.01)。Western blot法检测结果表明,实验组细胞内Fas蛋白、Caspase-3、VEGF165蛋白的表达水平均明显高于对照组,差异均有统计学意义(P<0.01)。结论:p75 NTR受体高表达可导致RPE细胞线粒体发生损伤,同时促进细胞凋亡,最终导致脉络膜新生血管的形成,表明p75 NTR受体可能是导致RPE细胞发生损伤的因素之一。

The gene expression of adenosine receptors in the processes of contrast induced nephropathy in mouse kidney

Objective: Contrast induced nephropathy (CIN) is the third leading cause of hospital acquired renal failure. The mechanism of CIN is not fully understood. The objectives of this study were to investigate the expression changes of the four subtypes of adenosine receptors (A1AR, A2AAR, A2BAR, and A3AR) following administration of contrast media in mice. Methods: C57BL/6J mice were randomized into treatment and control groups. Iodixanol (IDX) was administered to two treatment groups through retroorbital injection at two different dosages, 0.75 gI/kg and 2.75 gI/kg. Phosphate buffered saline (PBS) was given to the control group. Mice kidneys were harvested at day 3 and day 7 after Iodixanol administration. Kidney injuries and function were evaluated according to Hematoxylin and eosin stain, Ki67 protein expression, and TUNEL assay of paraffin embedded kidney sections, and plasma creatinine assay. RNA and protein were extracted from the kidney specimens. A1AR, A2AAR, A2BAR, and A3AR RNA and protein level of the samples were assessed using qRT-PCR and Western blotting, with GAPDH as an endogenous control. Results: H&E staining showed no significant histopathology injuries after Iodixanol administration. No evidence of kidney injury and functional impairment was found. However, there was an increased number of A1AR, A2AAR, A2BAR, and A3AR RNA transcripts detected in the kidney 3 days after Iodixanol injection. The RNA levels in all the four subtypes of adenosine receptors were increased 2-3 fold in the day 3 specimens and back to normal at day 7. Western blot demonstrated that A1AR, A2AAR, and A3AR expression increased 1.5 to 2 fold at day 3 and day 7 following Iodixanol injection. A2BAR baseline expression was low in normal physiological conditions and no significant change was detected by Western blot. Conclusions: Iodixanol significantly increases adenosine receptors gene expression in mice. This suggests that adenosine receptors may play a role in the development of CIN.