Recent Construction Technology Innovations and Practices for Large-Span Arch Bridges in China

Arch bridges provide significant technical and economic benefits under suitable conditions.In particular,concrete-filled steel tubular(CFST)arch bridges and steel-reinforced concrete(SRC)arch bridges are two types of arch bridges that have gained great economic competitiveness and span growth potential due to advancements in construction technology,engineering materials,and construction equipment over the past 30 years.Under the leadership of the author,two record-breaking arch bridges—that is,the Pingnan Third Bridge(a CFST arch bridge),with a span of 560 m,and the Tian’e Longtan Bridge(an SRC arch bridge),with a span of 600 m—have been built in the past five years,embodying great technological breakthroughs in the construction of these two types of arch bridges.This paper takes these two arch bridges as examples to systematically summarize the latest technological innovations and practices in the construction of CFST arch bridges and SRC arch bridges in China.The technological innovations of CFST arch bridges include cable-stayed fastening-hanging cantilevered assembly methods,new in-tube concrete materials,in-tube concrete pouring techniques,a novel thrust abutment foundation for nonrocky terrain,and measures to reduce the quantity of temporary facilities.The technological innovations of SRC arch bridges involve arch skeleton stiffness selection,the development of encasing concrete materials,encasing concrete pouring,arch rib stress mitigation,and longitudinal reinforcement optimization.To conclude,future research focuses and development directions for these two types of arch bridges are proposed.

ESMO2023:恩扎卢胺联合雄激素剥夺治疗对比安慰剂联合雄激素剥夺治疗在中国转移性激素敏感性前列腺癌患者中的疗效和安全性(中国ARCHES)

2019年发表的全球ARCHES试验(NCT02677896)结果显示,与安慰剂(placebo,PBO)+雄激素剥夺治疗(androgen deprivation therapy,ADT)相比,恩扎卢胺+ADT延长了转移性激素敏感性前列腺癌(metastatic hormone-sensitive prostate cancer,mHSPC)患者的总生存期和放射影像学无进展生存期(radiographic progression-free survival,rPFS)^([1])。然而,该试验无中国患者入组。欧洲肿瘤内科学会(European Society for Medical Oncology,ESMO)2023年会议报道了中国ARCHES研究(NCT04076059)的初步结果,这是一项评估恩扎卢胺+ADTvs.PBO+ADT在中国m HSPC患者中的疗效和安全性的多中心、随机、双盲、PBO对照的Ⅲ期试验^([2])。

Numerical Simulation Analysis of Welded Joints in Arch Ribs of Large Span Steel Pipe Arch Bridges

In order to study the residual stress distribution law of welded joints of arch ribs of large-span steel pipe concrete arch bridges,numerical simulation of temperature,stress and strain fields based on ABAQUS for welded joints of arch-ribbed steel tubes using 7-,8-and 9-layer welds is carried out and its accuracy is demonstrated.The steel pipe welding temperature changes,residual stress distribution,different processes residual stress changes in the law,the prediction of post-weld residual stress distribution and deformation are studied in this paper.The results show that the temperature field values and test results are more consistent with the accuracy of numerical simulation of welding,the welding process is mainly in the form of heat transfer;Residual high stresses are predominantly distributed in the Fusion zone(FZ)and Heat-affected zone(HAZ),with residual stress levels tending to decrease from the center of the weld along the axial path,the maximum stress appears in the FZ and HAZ junction;The number of welding layers has an effect on the residual stress distribution,the number of welding layers increases,the residual stress tends to decrease,while the FZ and HAZ high stress area range shrinks;Increasing the number of plies will increase the amount of residual distortion.

Health diagnosis of ultrahigh arch dam performance using heterogeneous spatial panel vector model

Currently,more than ten ultrahigh arch dams have been constructed or are being constructed in China.Safety control is essential to long-term operation of these dams.This study employed the flexibility coefficient and plastic complementary energy norm to assess the structural safety of arch dams.A comprehensive analysis was conducted,focusing on differences among conventional methods in characterizing the structural behavior of the Xiaowan arch dam in China.Subsequently,the spatiotemporal characteristics of the measured performance of the Xiaowan dam were explored,including periodicity,convergence,and time-effect characteristics.These findings revealed the governing mechanism of main factors.Furthermore,a heterogeneous spatial panel vector model was developed,considering both common factors and specific factors affecting the safety and performance of arch dams.This model aims to comprehensively illustrate spatial heterogeneity between the entire structure and local regions,introducing a specific effect quantity to characterize local deformation differences.Ultimately,the proposed model was applied to the Xiaowan arch dam,accurately quantifying the spatiotemporal heterogeneity of dam performance.Additionally,the spatiotemporal distri-bution characteristics of environmental load effects on different parts of the dam were reasonably interpreted.Validation of the model prediction enhances its credibility,leading to the formulation of health diagnosis criteria for future long-term operation of the Xiaowan dam.The findings not only enhance the predictive ability and timely control of ultrahigh arch dams'performance but also provide a crucial basis for assessing the effectiveness of engineering treatment measures.

A Nonlinear Explicit Model of A Non-Circular Subsea Tunnel-Liner System with An FGM Inverted Arch Under Mechanical Loading and Fire Fields

This paper proposes an explicit scheme to analyze the failure of a subsea polyhedral tunnel-liner system with an inverted arch under mechanical loading and fire fields.The thin-walled liner is made of Functionally Graded Materials(FGMs),which may improve the stability behavior of the tunnel-liner system.Hydrostatic pressure is inevitable in the liner since underground water may penetrate the cracks of the tunnel,and reach the outer surface of the liner.In addition,an elevated temperature loading is taken into account,considering that fire may occur in the tunnel-liner system.Under the combination of mechanical loading and thermal loading,the liner deforms into a single-lobe shape,which is depicted by a trigonometric function.The total potential energy is expressed quantitatively after the energy approach and thin-walled shell theory are used.The minimum potential energy is obtained when the critical buckling occurs.The critical buckling pressure is calculated,which considers the effect of the thermal field.The present analytical prediction is subsequently compared precisely with other closed-form solutions.Finally,the effects of several parameters,such as the geometric shapes,temperature variations,and volume fraction indices,are discussed to further survey the buckling performance of the nonlinear buckling of an FGM polyhedral liner with an inverted arch.One may address a polyhedral liner with fewer polyhedral sides,and a lower volume fraction index is recommended to rehabilitate cracked tunnels in engineering applications.

Effects of comprehensive nursing with cognitive behavioral therapy in orthodontic osteodilated arch treatment

BACKGROUND This work explored the effects of cognitive behavior therapy(CBT)-based comprehensive nursing intervention(CNI)mode in arch expansion to treat patients with orthodontic osteodilated arch(OOA).AIM To explore the application effect of CBT-based CNI model in orthodontic expansion arch treatment.METHODS Using convenient sampling method,81 patients with OOA were selected and rolled into a control group(Ctrl group,40 cases)and an observation group(Obs group,41 cases).During the treatment,patients in the Ctrl group received routine nursing intervention mode,and the those in the Obs group received CBT mode on the basis of this.Before and after intervention,the incidence of oral mucositis,the mastery rate of correct arch expansion method,self-rating anxiety scale score,soft scale index,and plaque index were compared for patients in different groups.In addition,satisfaction and complications were comparatively analyzed.RESULTS Incidence of oral mucositis in the Obs group was lower(14.6%vs 38.5%),and the mastery rate of correct arch expansion method was obviously higher(90.2%vs 55.0%)was obviously higher(all P<0.05).Meanwhile,the soft scale index and plaque index in the Obs group were much lower(P<0.05).The compliance(90.24%)and satisfaction(95.12%)in the Obs group were greatly higher(P<0.05).CONCLUSION The CBT-based CNI mode greatly improved the mastery rate of correct arch expansion method during arch expansion in treating patients with OOA and enhanced the therapeutic effect of arch expansion and the oral health of patients,improving the patient compliance.

基于SARIMA-ARCH的电量预测模型

电量预测是供电单位购电的重要依据,是电力经济稳定运行的根本基础。提出采用SARIMA-ARCH融合模型对某地区售电量进行预测。首先,采用季节时间序列分析方法(SARIMA)对月度电量时间序列进行建模,通过ACF和PACF图筛选确定出最佳模型阶数,得到季节性时间序列模型(SARIMA)基础预测模型;提取模型残差的波动性,建立自回归条件异方差(ARCH)模型;最后,将SARIMA-ARCH模型与常规SRIAM和ARIMA的预测值进行对比分析。结果表明,SARIMAARCH混合模型的预测精度较高。

基于ARCH族模型的股票超高频数据的波动性研究——以浦发银行为例

论文基于浦发银行股票的逐笔交易数据,利用ARCH族模型对其超高频数据中的波动性进行了研究。论文首先通过对数据的预处理和单位根检验,确保了数据的平稳性,随后应用多种ARCH族模型对波动性进行建模与比较,最终选择TGARCH(2,1,1)模型作为最优模型。该模型不仅能够捕捉数据中的波动集聚效应,还揭示了显著的波动非对称性。研究结果表明,浦发银行的股票收益波动性具有显著的持久性和杠杆效应,负面冲击对波动的影响大于正面冲击。基于这些发现,论文提出了加强高频交易监管、优化投资策略和强化风险管理等政策启示。

我国股市波动的ARCH类模型分析

股票价格的频繁波动是股票市场最明显的特征之一。 ARCH类模型可以成功地预测金融资产收益率的方差。通过对我国股价指数的统计描述 ,表明我国金融资产收益率存在自回归条件异方差特征 ,并表现出非正态性。利用 ARCH类模型对深圳成份指数的波动进行拟合 ,结果表明 。

Persistent left superior vena cava in right hemiarch replacement under deep hypothermic circulatory arrest:A case report

BACKGROUND Persistent left superior vena cava(PLSVC),a relatively rare thoracic vascular malformation,can inconvenience perfusionists and operators when encountered during deep hypothermic circulatory arrest(DHCA).CASE SUMMARY Herein,we describe the case of a patient with concurrent giant aortic arch aneurysm,aortic stenosis,and PLSVC.To treat these conditions,we performed right hemiarch and aortic valve replacements under DHCA.Notably,we applied“bilateral superior vena cava retrograde cerebral perfusion(RCP)”for cerebral protection,which significantly optimized the surgical procedure and reduced the risk of postoperative complications.The patient was discharged 14 d after surgery with no complications.CONCLUSION Surgical intervention for PLSVC under DHCA can be performed using the bilateral superior vena cava RCP approach.

基于GARCH族模型人民币离岸价格收益率波动预测分析

我国是个外贸依存度很高的国家,汇率的较大波动会对我国经济造成重大影响,准确预测汇率波动性能够为降低中国企业的外贸、投资的汇率风险规避提供一定的参考价值。因此,本文选取了2022年1月3日~2023年7月15日香港美元人民币市场的每日收盘价格,用2022年1月3日至2022年6月30日的样本内数据建模,并用模型进行2023年7月3日至2023年7月21日的样本外预测以评价模型的预测能力。研究结果显示,IGARCH模型是数据拟合模型最优的,反映了人民币离岸价格收益波动率受冲击影响持久。

基于ARMA-EGARCH-M模型的沪深股市波动性分析

文章讨论了ARCH模型族的拟合波动性的优缺点,建立ARMA-EGARCH-M模型,简要说明了此模型的优点;以2000年1月11日-2006年3月15日上证综指和深证成指收盘价为样本,对我国沪深股市收益率分布用ARMA-EGARCH-M模型进行拟合分析,结果表明该模型能更有效地拟合我国沪深股市的波动性;最后解释实证结果和分析了我国股市的行为。

Comparison and Selection of Arch-Rib Construction Schemes for Continuous Beam arch Composite Bridge of High Speed Railway

The paper summarizes the four different construction schemes based on engineering cases for the arch rib construction of continuous beam-arch composite bridges for high-speed railways.These methods include in-situ assembly,segmental lifting,incremental launching and longitudinal moving,and vertical rotation.The temporary structural designs,process methods,and technological equipment for each construction scheme are described in detail.The advantages and disadvantages of each scheme and its application scope under various conditions are analyzed,and opinions and suggestions for guiding the application of each scheme are proposed.The comparison and selection analyses show that the four arch rib construction schemes have certain applicability under different conditions such as bridge site status,bridge span,and construction environment.With the continuous increase of bridge span and progress of construction technological equipment,the arch rib construction technology is developing towards the overall erection direction.This leads to more obvious technical advantages of the segmental lifting method,incremental launching and longitudinal moving method,and vertical rotation method.Therefore,it is necessary to select the best construction scheme according to the construction status and technical conditions during application.

ARCH类模型研究及其在沪市A股中的应用

本文主要介绍ARCH(AutoregressiveConditionalHeteroskedasticity)模型、GARCH模型和E GARCH模型 ,分析这些模型的特点和适用范围 ,并在模型中引入t分布取代正态分布假设 ,最后利用这些模型对上证指数进行了实证分析。

基于比较视角的我国股票市场波动ARCH效应研究

我国同期的主板市场不存在ARCH效应,中小板市场存在弱势ARCH效应,创业板市场存在明显的ARCH效应;GARCH(1,2)模型能较好地刻画中小板指数,GARCH(1,1)模型能较好地刻画创业板指数;EGARCH(1,2)能较好地刻画中小板市场波动的非对称性,EGARCH(1,1)模型能较好地刻画创业板市场波动的非对称性;GARCH(1,2)-M模型不能有效刻画中小板指数,GARCH(1,1)-M也不能有效刻画创业板指数,表明中小板市场及创业板市场日收益序列对风险溢价的敏感性不强。

Mechanical properties and influence mechanism of confined concrete arches in high-stress tunnels

Deep underground projects(e.g., coal mines), are often faced with complex conditions such as high stress and extremely soft rock. The strength and rigidity of the traditional support system are often insufficient,which makes it difficult to meet the requirements of ground control under complex conditions. As a new support form with high strength and rigidity, the confined concrete arch plays an important role in controlling the rock deformation under complex conditions. The section shape of the tunnel has an important impact on the mechanical properties and design of the support system. However, studies on the mechanical properties and influence mechanism of the new confined concrete arch are rarely reported. To this end, the mechanical properties of traditional U-shaped steel and new confined concrete arches are compared and comparative tests on arches of circular and straight-leg semicircular shapes in deep tunnels are conducted. A large mechanical testing system for underground engineering support structure is developed. The mechanical properties and influence mechanism of confined concrete arches with different section shapes under different loading modes and cross-section parameters are systematically studied. Test results show that the bearing capacity of the confined concrete arch is 2.10 times that of the U-shaped steel arch, and the bearing capacity of the circular confined concrete arch is 2.27 times that of the straight-leg semicircular arch. Among the various influencing factors and their engineering parameters,the lateral stress coefficient has the greatest impact on the bearing capacity of the confined concrete arch,followed by the steel pipe wall thickness, steel strength, and core concrete strength. Subsequently, the economic index of bearing capacity and cost is established, and the optimization design method for the confined concrete arch is proposed. Finally, this design method is applied to a high-stress tunnel under complex conditions, and the deformation of the surrounding rock is effectively controlled.

我国创业板市场波动的ARCH效应研究

相对于主板市场而言,创业板上市公司具有明显的高科技、高成长、波动性大等特点。ARCH类模型较好地拟合了资本市场中资产收益的"尖峰厚尾"、"波动率集聚"等一系列的特征,广泛应用于资产收益与波动率的分析。选取2010/6/1—2012/5/31的创业板指数日收盘价,运用GARCH族模型对我国创业板指数的日收益及波动率进行研究的结果表明,我国创业板市场存在明显的ARCH效应,且GARCH(1,1)、EGARCH(1,1)模型都能较好地拟合,而GARCH(1,1)-M在验证指数波动对收益影响却不显著,表明创业板市场收益与波动关联性不强。

Deformation critical threshold estimation of Xiaowan ultrahigh arch dam with time-varying grey model

The structural behavior of the Xiaowan ultrahigh arch dam is primarily influenced by external loads and time-varying characteristics of dam concrete and foundation rock mass during long-term operation. According to overload testing with a geological model and the measured time series of installed perpendicular lines, the space and time evolution characteristics of the arch dam structure were analyzed, and its mechanical performance was evaluated. Subsequently, the deformation centroid of the deflective curve was suggested to indicate the magnitude and unique distribution rules for a typical dam section using the measured deformation values at multi-monitoring points. The ellipse equations of the critical ellipsoid for the centroid were derived from the historical measured time series. Hydrostatic and seasonal components were extracted from the measured deformation values with a traditional statistical model, and residuals were adopted as a grey component. A time-varying grey model was developed to accurately predict the evolution of the deformation behavior of the ultrahigh arch dam during future operation. In the developed model, constant coefficients were modified so as to be time-dependent functions, and the prediction accuracy was significantly improved through introduction of a forgetting factor. Finally, the critical threshold was estimated, and predicted ellipsoids were derived for the Xiaowan arch dam. The findings of this study can provide technical support for safety evaluation of the actual operation of ultrahigh arch dams and help to provide early warning of abnormal changes.

Structural Damage Identification System Suitable for Old Arch Bridge in Rural Regions: Random Forest Approach

A huge number of old arch bridges located in rural regions are at the peak of maintenance.The health monitoring technology of the long-span bridge is hardly applicable to the small-span bridge,owing to the absence of technical resources and sufficient funds in rural regions.There is an urgent need for an economical,fast,and accurate damage identification solution.The authors proposed a damage identification system of an old arch bridge implemented with amachine learning algorithm,which took the vehicle-induced response as the excitation.A damage index was defined based on wavelet packet theory,and a machine learning sample database collecting the denoised response was constructed.Through comparing three machine learning algorithms:Back-Propagation Neural Network(BPNN),Support Vector Machine(SVM),and Random Forest(R.F.),the R.F.damage identification model were found to have a better recognition ability.Finally,the Particle Swarm Optimization(PSO)algorithm was used to optimize the number of subtrees and split features of the R.F.model.The PSO optimized R.F.model was capable of the identification of different damage levels of old arch bridges with sensitive damage index.The proposed framework is practical and promising for the old bridge’s structural damage identification in rural regions.