A Comparative Study on the Post-Buckling Behavior of Reinforced Thermoplastic Pipes(RTPs)Under External Pressure Considering Progressive Failure

The collapse pressure is a key parameter when RTPs are applied in harsh deep-water environments.To investigate the collapse of RTPs,numerical simulations and hydrostatic pressure tests are conducted.For the numerical simulations,the eigenvalue analysis and Riks analysis are combined,in which the Hashin failure criterion and fracture energy stiffness degradation model are used to simulate the progressive failure of composites,and the“infinite”boundary conditions are applied to eliminate the boundary effects.As for the hydrostatic pressure tests,RTP specimens were placed in a hydrostatic chamber after filled with water.It has been observed that the cross-section of the middle part collapses when it reaches the maximum pressure.The collapse pressure obtained from the numerical simulations agrees well with that in the experiment.Meanwhile,the applicability of NASA SP-8007 formula on the collapse pressure prediction was also discussed.It has a relatively greater difference because of the ignorance of the progressive failure of composites.For the parametric study,it is found that RTPs have much higher first-ply-failure pressure when the winding angles are between 50°and 70°.Besides,the effect of debonding and initial ovality,and the contribution of the liner and coating are also discussed.

White Matter Lesions in Young-Middle Aged Migraineurs with Patent Foreman Ovale: A Case-Control Study

Background:White matter lesion(WML)is common in aging brain and is associated with cognitive impairment and dementia.However,recent studies reported an association between patent foramen ovale(PFO)and WML in migraineurs,especially in young,middle-aged migraineurs.Our retrospective,case-control study aims to describe the clinical characteristics of WML in this population and to explore potential risk factors.Methods:226 patients with migraine and PFO were consecutively initially screened.Relevant factors were selected by the least absolute shrinkage and selection operator(LASSO)regression and multivariable logistic regression model.A Nomogram was employed to visualize the prediction model conveniently.The discrimination and calibration abilities were evaluated using the Receiver Operating Characteristic(ROC)curve,the Hosmer-Lemeshow test,and calibration curves.Results:One hundred and nineteen participants were ultimately enrolled in our study,with a median age of 36.9±12.7 years and 80.7%of females.Brain magnetic resonance imaging MRI showed 67(56.3%)patients had WML,whereas 52(43.7%)patients were categorized into the non-WML group.LASSO regression screened out potential variables and subsequent multivariate analysisfinally identified age,mean platelet volume,andfibri-nogen(FIB)as independent predictive factors of WML.The area under the ROC curve(AUC)was 0.807.Hos-mer-Lemeshow test and calibration curve verified a consistency between the predicted and actual probability.Conclusion:The predictive nomogram established and validated in our study may assist clinicians in screening WML among young middle-aged migraineurs with PFO and developing individualized preventive and treatment strategies.

Multiple paradoxical embolisms caused by central venous catheter thrombus passing through a patent foramen ovale: A case report

BACKGROUND To date,this is the first case of a paradoxical embolism(PDE)that concurrently manifested in the coronary and lower limb arteries and was secondary to a central venous catheter(CVC)thrombus via a patent foramen ovale(PFO).CASE SUMMARY Here,we report a case of simultaneous coronary and lower limb artery embolism in a PFO patient carrier of a CVC.The patient presented to the hospital with acute chest pain and lower limb fatigue.Doppler ultrasound showed a large thrombus in the right internal jugular vein,precisely at the tip of the CVC.Transthoracic and transesophageal echocardiography confirmed the existence of a PFO,with inducible right-to-left shunting by the Valsalva maneuver.The patient was administered an extended course of anticoagulation therapy,and then the CVC was successfully removed.Percutaneous PFO closure was not undertaken.There was no recurrence during follow-up.CONCLUSION Thus,CVC-associated thrombosis is a potential source for multiple PDE in PFO patients.

Safety and Efficacy of Biodegradable Patent Foramen Ovale Occluder in Patients with Migraine:A Clinical Trial

Background:Transcatheter closure of patent foramen ovale(PFO)has been widely accepted as a highly effective way to treat high-risk PFO-related diseases.However,traditional non-degradable occluders made of metal alloys will permanently exist in the body,resulting in thrombosis,valve damage,hemolysis,arrhythmia,or other complications.The biodegradable PFO occluder developed by Shanghai Mallow Medical Instrument Co.,Ltd.,China can be fully absorbed and degrade into nontoxic ingredients,reducing postoperative complications.Objectives:To study the safety and efficacy of biodegradable PFO occluders in treating PFO.Methods:This single-center clinical trial collected 30 patients treated with a biodegradable PFO occluder.The follow-up period lasted 12 months to analyze the echocardiographic characteristics and headache relief through HIT-6 scores.Results:The immediate success rate was 100%,with no intraoperative severe occlusion-related complications.The contrast transcranial Doppler(cTCD)at 12 months showed that all patients’right-to-left shunts(RLS)were grade I or 0 with no serious postoperative complications,indicating the overall success rate was 100%.The biodegradable PFO occluder mostly degraded six months after the occlusion.Conclusion:PFO closure with a Mallow biodegradable occluder is safe and effective and has no severe complications.

Platypnea-Orthodeoxia Syndrome in an Elderly Patient Treated with Percutaneous Patent Foramen Ovale Closure: Report of a Case and Review of the Literature

Introduction: Platypnea-Orthodeoxia syndrome is characterized by dyspnea and hypoxia in the upright position, usually improving in the supine position. Two components are required: an interatrial or intrapulmonary shunt, and a functional component. Diagnosis is made by contrast ultrasonography. We report a case of Platypnea-Orthodeoxia syndrome revealed by positional dyspnea in an 87-year-old patient. The aim of this study is to describe the clinical, therapeutic and evolutionary profile of this syndrome. Case Presentation: This is an 87-year-old patient with a history of pulmonary embolism (PE) and stroke. He was seen for dyspnea and desaturation in orthostatism, revealing a patent foramen ovale (PFO). Progression was favorable after closure of the PFO. Conclusion: Platypnea-Orthodeoxia syndrome may be presented as simple exertional dyspnea. The clinician should check for improvement in symptoms and/or oxygenation during decubitus. Definitive treatment consists of percutaneous closure of the shunt.

The calculation of the Reproducibility Error in the technological system with the clamp on the gas power

The paper deduced a calculation formula by the classic control theory on the Reproducibility Error of parts processing in the technology system,the flexible clamp system, with the clamping device on the gas power,and analyzed its influencing factor with examples,the Reproducibility Error law:\ The larger the diameter of the cylinder,the smaller the error; the slower the tool speed,(k values smaller),the smaller the error.

基于OVAL的新型漏洞评估系统

漏洞评估技术基于防患于未然思想,采用主动探测方法发现系统存在的安全漏洞并提供相应解决方案.针对目前漏洞评估系统存在误报率高、扫描时间长且需要开发攻击代码的缺点,本文提出一种基于OVAL的新型漏洞评估系统.该系统由控制台、数据中心和检测代理3大模块组成,这三个模块协同实现漏洞评估.与现有漏洞评估系统相比,具有精度高、对目标系统性能影响小、评估时间短和可扩展性强的优点,而且免除传统漏洞评估系统所需的攻击代码开发工作.

Variable-stiffness composite cylinder design under combined loadings by using the improved Kriging model

The large design freedom of variable-stiffness (VS) composite material presupposes its potential for wide engineering application. Previous research indicates that the design of VS cylindrical structures helps to increase the buckling load as compared to quasi-isotropic (QI) cylindrical structures. This paper focuses on the anti-buckling performance of VS cylindrical structures under combined loads and the efficient optimization design method. Two kinds of conditions, bending moment and internal pressure, and bending moment and torque are considered. Influences of the geometrical defects, ovality, on the cylinder's performances are also investigated. To increase the computational efficiency, an adaptive Kriging meta-model is proposed to approximate the structural response of the cylinders. In this improved Kriging model, a mixed updating rule is used in constructing the meta-model. A genetic algorithm (GA) is implemented in the optimization design. The optimal results show that the buckling load of VS cylinders in all cases is greatly increased as compared with a QI cylinder.

从OVAL漏洞信息转换到Nessus扫描插件的研究与实现

网络安全漏洞扫描应充分考虑执行的效率和信息的共享。本文通过对OVAL和Nessus的介绍,分析O- VAL Definition与Nessus plugin之间的异同,提出并实现了一种将OVAL公布的漏洞信息转换成Nessus扫描插件的方法,共享了漏洞信息,并提升了漏洞检测的品质。最后经过实验说明该方法的可行性。

Three-roller continuous setting round process for longitudinally submerged arc welding pipes

In order to solve the problems of excess ovality and cross-section distortion of longitudinally submerged arc welding pipes after forming,a new three-roller continuous setting round process was proposed.This process can be divided into three stages:loading stage,roll bending stage and unloading stage.Based on the discretization idea,the mechanical model of the primary statically indeterminate problem of the longitudinally submerged arc welding pipes at the roll bending stage was established,and the deformation response was obtained.The simulation and theoretical results show that there are three positive bending regions and three reverse bending regions along the circumference of the pipe.The loading force of each roller shows growth,stability and downward trend with time.The error between the theoretical fitting curve and the simulated data point is very small,and the simulation results verify the reliability of the theoretical calculation.The experimental results show that the residual ovality decreases with the increase of the reduction,and the reduction of the turning point is the optimum reduction.In addition,the residual ovality of the pipe is less than 0.7%without cross-section distortion,which verifies the feasibility of this process.

Collapse Analysis of Imperfect Subsea Pipelines Based on 2D High-Order Nonlinear Model

To study the collapse of imperfect subsea pipelinos, a 2D high-order nonlinear model is developed. In this model, the large deformation of the pipes is considered by raiaining the high-order nonlinear terms of strain. In addi-tion, the J2 plastic flow theory is adopted to describe the elasioplastic constitutive relations of material. The quasi-static process of collapse is analyzed by the increment method. For each load step, the equations based on the principle of virtual work are presented and solved by the discrete Newton＇s method. Furthermore, finite element simulations and full-scale experiments were preformed to validate the results of the model. Research on the major influencing factors of collapse pressure, including D/t, material type and initial ovality, is also presented.

Theoretical analysis on quasi-static lateral compression of elliptical tube between two rigid plates

Based on the rigid plastic theory; the load-deflection functions with and without considering the effect of strain hardening are respectively derived for an elliptical tube under quasi-static compression by two parallel rigid plates. The non-dimensional load-deflection responses predicted by the present theory and the finite element simula- tions are compared, and the favorable agreement is found. The results show that strain hardening may have a noticeable influence on the load-deflection curves of an elliptical tube under quasi-static compression. Compared with the circular counterpart, the ellip- tical tube exhibits different energy absorption behavior due to the difference between the major axis and the minor axis. When loaded along the major axis of a slightly oval tube, a relative even and long plateau region of the load-deflection curve is achieved, which is especially desirable for the design of energy absorbers.

Correlations between the optic nerve head morphology and ocular biometrics in highly myopic eyes

AIM： To analyze peripapillary atrophy β/γ zone （PPA-β/γ） and the optic disc ovality index, and to assess their associations with the axial length （AL）, refractive error, best corrected visual acuity （BCVA）, choroidal thickness （CT）, and age in highly myopic eyes. METHODS： This was a retrospective observational case series. The study included 667 patients consecutively examined for highly myopic eyes [spherical equivalent ≤-6.0 diopters （D） and AL≥26 mm] with or without myopic retinopathy. Each patient went through a comprehensive ophthalmological examination that included spectral domain optical coherence tomography （SD-OCT） of the macula, A-mode ultrasonography, and a cycloplegic refraction test. The ovality index and PPA-β/γ area were measured from optic disc photographs. RESULTS： A significant association was seen between PPA-β/γ area and the ovality index （P=0.000, r=-0.232）. The PPA-β/γ area increased significantly with a longer AL, older age, worse BCVA, higher refractive error, and thinner choroid （P〈0.01）. The oval disc was significantly correlated with a longer AL, older age, worse BCVA, higher refractive error, larger PPA-β/γ area, and thinner choroid （P〈0.01）. CONCLUSION： The PPA-β/γ zone and ovality index in highly myopic eyes show distinct associations with the AL, refractive error, BCVA, age, and CT.

汽车试验场高速环道几何线形设计研究及程序开发

在既有高速环道理论基础上对高速环道几何线形设计进行深入研究,在对比了麦克康奈尔(McConnell)和布劳斯(Bloss)缓和曲线设计法的特点后,引入积分算法对麦克康奈尔曲线的计算进行优化,并结合实际应用开发了汽车试验场高速环道几何线形设计程序(OTD)。

OVALS海洋资料同化系统并行计算研究

海洋数值预报技术的发展与高性能计算密切相关。为提高OVALS海洋资料同化系统的时效性,本文实现了OVALS系统的并行化。在温盐资料同化模块并行化过程中,本文提出了层优先处理器划分算法,并研究了基于该算法的并行I/O、全局通讯等实现方法;在高度计资料同化模块并行化过程中,设计实现了基于预处理的非规则区域分解算法,较好地实现了OVALS并行计算负载平衡。数值实验表明,OVALS并行系统在36并行规模下取得了17.45的并行加速比。

Study on First-Yield Collapse of Submarine Pipelines

The first-yield collapse of submarine pipelines with an initial out-of-roundness imperfection under combined bending and external pressure load is formulated by means of the Von. Mises yield criterion. The formula reduces to Timoshenko and Gere's expression in the case of external pressure load alone. The influence curves of various parameters on the yield strength are presented, the collapse of submarine pipelines in a deep water region is numerically predicted, and the effect of pre-yield nonlinear bending on the yield strength is also examined.

Microstructural features of parapapillary gamma zone and beta zone in non-myopic eyes

Background:To investigate the microstructural features of parapapillary gamma zone and beta zone and their relationship with three-dimensional optic disc shape in non-myopic eyes.Methods:This cross-sectional study included 62 non-myopic eyes with parapapillary gamma or beta zone and 70 control eyes.On the spectral domain optical coherent tomography(SD-OCT)images,we measured the area of gamma zone and beta zone,the length of border tissue,and related disc parameters.The disc ovality index,disc rotation degrees around three axes,Bruch’s membrane opening(BMO)ovality ratio were calculated based on the SD-OCT images.Results:The parapapillary gamma zone composed by externally oblique border tissue was found in inferior,nasal and temporal quadrants of the non-myopic eyes.The presence of gamma zone in non-myopic eyes was correlated with smaller disc ovality index,larger rotation degree around vertical and horizontal axes,and larger BMO ovality ratio(P<0.001).Compared with the non-temporal gamma zone group,eyes with temporal gamma zone had a longer axial length and rotated more around vertical axes(P<0.001).Multivariate analysis showed that the area of gamma zone was correlated with the disc ovality index(P<0.001).The presence and area of beta zone was correlated with age(P<0.01).Conclusions:In non-myopic eyes,the parapapillary gamma zone composed by external oblique border tissue was significantly associated with the disc ovality and disc rotations around vertical and horizontal axes.From a biomechanical perspective,parapapillary gamma zone may contribute to the optic disc stability in association with the structure of BMO.

基于OVAL新型漏洞检测器漏洞库的设计与实现

针对目前主流的漏洞扫描技术中漏洞库的不完整,本文提出了一种新型的基于OVAL的漏洞检测器,其漏洞库可根据需要扫描系统软件、硬件和配置信息等,并以此确定系统中存在的安全漏洞。此检查器所能扫描的操作系统很多,该篇文章以RedHat为载体讲述工作原理和实现。

分布式漏洞检测系统的设计与实现

针对目前主流的漏洞检测工具检测时间长、误报率高以及使用攻击代码影响系统运行等缺点,提出了一种基于OVAL的分布式漏洞检测系统,采用基于主机的漏洞检测方法发现系统存在的安全漏洞.该系统由检测代理和中心管理子系统组成,其中检测代理执行检测插件对目标主机系统进行漏洞检测,而中心管理子系统提供安全知识定义和检测算法.经实验测试,与其他漏洞检测工具相比,具有检测速度快、精度高、对网络运行状况影响小和可扩展性强的优点.适用于检测大规模局域网中各主机系统的漏洞状况.

川芎内生菌Pseudeurotium ovale代谢产物研究

通过大孔树脂柱层析、凝胶柱层析和高效液相色谱等方法对川芎中分离得到的内生菌Pseudeurotium ovale的代谢物进行分离纯化,从中分离得到5个化合物,并通过核磁共振和质谱等波谱学技术手段确认所有化合物的结构,其中包含一个新的化合物4-methoxy-3-methyl-6-(1 E,3 E)-1,3-pentadien-1-yl-2 H-pyran-2-one(1)和四个首次从中分离得到的已知化合物:(2 E,4 E)-1-(2,6-dihydroxy-3,5-dimethylphenyl)-2,4-hexadien-1-one(2)、2-deoxy-sohirnone C(3)、trichodimerol(4)、3,7-dihydroxy-1,9-dimethyl-dibenzofuran(5)。体外抗炎活性测试表明化合物1可抑制经脂多糖(LPS)处理的RAW 264.7细胞中NO、IL-6和TNF-α等炎症因子的分泌。