Accuracy and Utility of Vessel Analysis Using Non-Contrast CT for Planning Endovascular Aortic Repair

Objectives: This study aimed to determine whether errors in vascular measurements would affect device selection in endovascular aortic repair (EVAR) by comparing measurements obtained using non-contrast computed tomography (NCT) with those obtained using contrast-enhanced CT (CECT). Materials and Methods: This single-center, retrospective study included 25 patients who underwent EVAR for abdominal aortic aneurysm at our institution. A 1-mm horizontal cross-sectional slice of NCT and CECT from each patient was retrospectively reviewed. The area from the abdominal aorta to the common iliac artery was divided into four zones. A centerline was created using the NCT by manually plotting the center points. Subsequently, the centerlines were automatically extracted and manually corrected during the arterial phase of CECT. The diameter and length of each zone were measured for each modality. The mean diameters and lengths of the target vessels were compared between NCT and CECT. Results: The measurements obtained using both methods were reproducible and demonstrated good agreement. The mean differences in vessel length and diameter measurements for each segment between NCT and CECT were not statistically significant, indicating good consistency. Conclusion: NCT may be useful for preoperative EVAR evaluation in patients with renal dysfunction or allergies to contrast agents.

Exploration on the Optimization Strategy for the Layup of Composite Material Pressure Vessels Based on Advanced Algorithms

This study aims to explore the influence of the laying angle on the pressure shell structure made of composite materials under the condition of a fixed shape. By using a composite material composed of a mixture of T800 carbon fiber and AG80 epoxy resin to design pressure vessels, this material combination can significantly improve the interlaminar shear strength and heat resistance. The article elaborates on the basic concepts and failure criteria of composite materials, such as the maximum stress criterion, the maximum strain criterion, the Tsai-Hill criterion, etc. With the help of the APDL parametric modeling language, the arc-shaped, parabolic, elliptical, and fitting curve-shaped pressure vessel models are accurately constructed, and the material property settings and mesh division are completed. Subsequently, APDL is used for static analysis, and the genetic algorithm toolbox built into Matlab is combined to carry out optimization calculations to determine the optimal laying angle. The research results show that the equivalent stress corresponding to the optimal laying angle of the arc-shaped pressure vessel is 5.3685e+08 Pa, the elliptical one is 5.1969e+08 Pa, the parabolic one is 5.8692e+08 Pa, and the fitting curve-shaped one is 5.36862e+08 Pa. Among them, the stress distribution of the fitting curve-shaped pressure vessel is relatively more uniform, with a deformation of 0.568E−03 m, a minimum equivalent stress value of 0.261E+09 Pa, a maximum equivalent stress value of 0.537E+09 Pa, and a ratio of 0.48, which conforms to the equivalent stress criterion. In addition, the fitting curve of this model can adapt to various models and has higher practical value. However, the stress distribution of the elliptical and parabolic pressure vessels is uneven, and their applicability is poor. In the future, further exploration can be conducted on the application of the fitting curve model in composite materials to optimize the design of pressure vessels. This study provides important theoretical support and practical guidance for the design of composite material pressure vessels.

不同静电纺丝膜上骨髓间充质干细胞的黏附、增殖与成血管平滑肌分化

背景:临床上迫切需要小口径人工血管来治疗冠状动脉和外周动脉疾病,目前,血管组织工程已成为制备小口径人工血管的主要方法,选择合适的生物材料和细胞来源是小口径组织工程血管构建成功的关键因素。目的:观察4种静电纺丝膜材料对骨髓间充质干细胞增殖、黏附及分化为血管平滑肌细胞的影响。方法:分离提取SD大鼠骨髓间充质干细胞。将骨髓间充质干细胞分别接种于聚己内酯(PCL)、聚己内酯-透明质酸(PCL-HA)、聚己内酯-丝素蛋白(PCL-SF)、聚己内酯-明胶(PCL-GEL)静电纺丝膜材料上,培养1,3,7 d后,扫描电镜下观察材料上的细胞排布,鬼笔环肽染色观察材料上的细胞增殖与黏附,qRT-PCR检测材料上细胞分泌的CD90、Meflin、转化生长因子βmRNA表达;向血管平滑肌细胞诱导分化7 d后,qRT-PCR检测材料上细胞ɑ-平滑肌肌动蛋白mRNA表达。结果与结论:①扫描电镜下可见骨髓间充质干细胞在4种静电纺丝膜上均沿着静电纺丝膜的纤维走向排列;②鬼笔环肽染色显示,骨髓间充质干细胞在4种静电纺丝膜上分布规律,均沿着纤维走向呈现平行分布,并且PCL-HA、PCL-SF、PCL-GEL静电纺丝膜较PCL静电纺丝膜更有利于骨髓间充质干细胞的增殖、黏附,PCL-SF静电纺丝膜相较于PCL-HA、PCL-GEL静电纺丝膜更有利于骨髓间充质干细胞的增殖、黏附;③qRT-PCR检测显示,4种静电纺丝膜材料均可维持骨髓间充质干细胞CD90和Meflin的mRNA表达,组间比较差异无显著性意义(P>0.05);PCL-HA、PCL-SF、PCL-GEL组培养1,7 d的转化生长因子βmRNA表达高于PCL组(P<0.05),PCL-SF组培养3,7 d的转化生长因子βmRNA表达高于其他3组(P<0.05),PCL-HA组培养7 d的转化生长因子βmRNA表达高于PCL-GEL组(P<0.05);④qRT-PCR检测显示,PCL-SF组ɑ-平滑肌肌动蛋白mRNA表达高于其他3组(P<0.05),PCL-HA组ɑ-平滑肌肌动蛋白mRNA表达高于PCL组(P<0.05);⑤结果表明:相较于PCL、PCL-HA、PCL-GEL静电纺丝膜,PCL-SF静电纺丝膜与骨髓间充质干细胞结合更适合制备小口径组织工程血管。

抗纤维化与促“H”型血管核壳结构生物支架修复临界骨缺损

背景:在骨组织愈合过程中,促进新生骨的血管化是加速骨组织修复的常用策略,然而骨缺损修复过程中过快的纤维化进程常常被忽略。目的:设计并制备一种具有调节新生骨痂内纤维化及血管化进程的核壳结构仿生支架,表征其物理学特征,验证其体内外抗纤维化与促成骨性能。方法:制备具有调节新生骨痂内纤维化及血管化进程的核壳结构仿生支架,外层壳结构由聚己内酯静电纺丝纳米纤维负载成纤维细胞活化蛋白抑制剂组成,内层核结构由甲基丙烯酸酐明胶水凝胶负载去铁胺组成,表征静电纺丝和水凝胶的物理学特征,利用活死染色与CCK-8实验验证材料的生物相容性。通过成纤维细胞体外实验分析支架壳结构的抗纤维化作用,通过MC3T3-E1细胞体外实验分析支架壳结构中成纤维细胞活化蛋白抑制剂的促成骨作用,通过人脐静脉内皮细胞分析支架核结构中去铁胺的促血管形成作用。通过大鼠临界骨缺损实验评估核壳结构仿生支架的骨修复作用。结果与结论:①核壳结构仿生支架具有良好的生物相容性,静电纺丝技术制备的聚己内酯电纺纤维具有疏水性,在物理层面上有效阻隔外源性纤维组织长入,电纺纤维膜在2周内可有效释放抗纤维化药物成纤维细胞活化蛋白抑制剂,释放的抗纤维化药物可以抑制骨缺损周围成纤维细胞的生长、黏附,有效降低成纤维相关蛋白的表达,同时可促进MC3T3-E1细胞成骨蛋白的表达,加快其矿化速度;支架核结构中的去铁胺可促进人脐静脉内皮细胞的迁移、成管能力,并促进其强烈表达“H”血管特征性蛋白。②在SD大鼠的股骨制造临界骨缺损模型中,相较于聚己内酯膜,核壳结构仿生支架实现了骨缺损的有效修复。③结果表明,核壳结构仿生支架在预防骨痂过度纤维化的同时促进新生骨痂内“H”血管形成,能有效避免骨不连的发生,加速临界骨缺损修复进程。

Studies on the Molecular Structure of Vessels in Secondary Xylem of Stem from Three Carambola Varieties

[Objective] The aim of this study was to provide the theoretical basis for variety identification of carambola and pomiculture.[Method] The molecular structure of vessels in stem secondary xylem from three carambola varieties of Malaysia 8,Misi and Malaysia B17 were studied by cell image analysis system and microphotography.[Result] The molecular structure of vessels in stem secondary xylem from carambola was as follows:the first type had tails in two ends,the second type had tail in one end,and the third type had no tails in two ends.The average length of vessel elements was from 328.88 to 366.09 μm,while its average width was from 44.61 to 52.43 μm.Most of the end wall was simple perforation plates,while the alternate-opposite pitting was the major forms of pitting.[Conclusion] Most characteristics of vessel elements from carambola were evolutionary characters of vessel elements in the process of phylogeny,but there were more primitive characters,for example,both two ends of vessel had tails or just one end had tail,and end wall was inclined.The molecular structure of vessel from carambola was in accordance with its ecological adaptability,and the growth characteristics of different varieties were also in accordance with the difference of molecular structure of vessel.

Choke Vessels扩展的研究进展

穿支皮瓣是创伤修复的研究热点,穿支皮瓣研究的重点和难点则在于choke vessels。我们对近年来choke vessels扩展研究的相关文献进行综述,目前的研究主要聚焦于形态学的描述,其扩张机制很可能是剪切力变化,激活TRPV4,通过NF-kb通路而导致choke vessels扩张。

干细胞在小口径人工血管内皮化中的应用

背景:小口径人工血管移植后由于血栓形成和内膜增生等原因造成管腔狭窄甚至闭塞,运用干细胞作为种子细胞实现人工血管的内皮化有助于改善血管移植后的远期通畅率。目的:总结干细胞在小口径人工血管内皮化中应用的研究进展。方法:由第一作者检索Pub Med和万方数据库2013-2023年发表的相关文献,英文检索词为“vascular graft,tissue-engineered blood vessel/vascular tissue engineering,endothelialization,stem cells,endothelial progenitor cells,mesenchymal stem cells,induced pluripotent stem cells,embryonicstemcells”,中文检索词为“人工血管,组织工程血管/血管组织工程,内皮化,干细胞,内皮祖细胞,间充质干细胞,诱导多能干细胞,胚胎干细胞”,检索近10年国内外关于干细胞应用于小口径人工血管内皮化的相关文献,初检文献552篇,根据纳排标准最终选取81篇文献进行综述。结果与结论:(1)远期通畅率不理想限制了小口径人工血管的临床应用,造成远期通畅率低下的主要原因是血栓形成和内膜增生。天然血管内皮层具有良好的抗血栓及内膜增生性能,内皮化可以模拟天然血管的特性,是提升远期通畅率的有效手段。(2)小口径人工血管植入体内后会经历体内内皮化过程,但难以形成完整的内皮层。干细胞具有分化为内皮细胞的潜能,体内招募干细胞或将其作为种子细胞种植在人工血管内表面是实现内皮化的研究策略。(3)将内皮祖细胞、间充质干细胞、诱导多能干细胞及胚胎干细胞等作为种子细胞种植均能够一定程度改善小口径人工血管的远期通畅率,且它们各具优势。内皮祖细胞便于获取且可直接用于种植;间充质干细胞来源广泛且具有旁分泌和调节免疫的功能;诱导多能干细胞来源丰富且可消除免疫原性;胚胎干细胞增殖能力强且能多向分化。(4)将干细胞用于人工血管的研究目前仍未转化至临床,未来需要进一步研究并促进临床转化。

神经纤毛因子1在骨折愈合中促进骨-血管偶联的作用

背景:神经纤毛因子1在骨折愈合过程中发挥重要作用,尤其是在促进骨-血管偶联方面。骨-血管偶联是骨折愈合过程中的关键事件之一,包括血管(尤其是H型血管)、新骨形成以及它们之间的关联。目的:回顾神经纤毛因子1在骨折愈合过程中促骨-血管偶联作用的研究进展。方法:在中国知网、PubMed数据库检索1982年1月至2024年4月发表的文献,以“Neuropilin-1,neuropilin 1,NRP1,neuropilin-1,NRP-1,Neuropilin 1,Nrp1,Nrp-1”为检索词,从中选择与骨折愈合、H型血管、动脉、骨细胞、骨-血管偶联关系紧密的文献43篇,增加手工检索的文献24篇,最终得到67篇文献。结果与结论:(1)在骨折愈合过程中骨-血管偶联的关键事件包括血管生成、新骨形成以及它们之间的关联,其中H型血管生成是骨折愈合过程中的关键事件之一,H型血管由血管内皮细胞以及周细胞组成;新骨形成主要是由成骨细胞、破骨细胞以及软骨细胞等骨细胞共同完成的;(2)神经纤毛因子1可以通过血管内皮生长因子和血小板衍生生长因子促进内皮细胞迁移、稳定,增强周细胞稳定性及其与内皮细胞之间的关联,从而促进血管再生;(3)神经纤毛因子1通过促进成骨细胞和软骨细胞形成、抑制破骨细胞生成来促进骨再生;(4)神经纤毛因子1可能是血管和骨偶联的关键因子之一;(5)局部应用神经纤毛因子1及其生物制剂,或将神经纤毛因子1、纳米载药系统以及高分子智能聚合材料等生物工程材料融合,为骨折治疗提供了新思路,有着广阔的应用前景。

MSCT图像后处理Add Vessel技术在髂动脉闭塞侧支血管成像中的应用价值

目的 :探讨MSCT的VR血管生长(AV)技术在髂动脉(IA)闭塞侧支血管成像中的临床应用价值。方法 :选择IA闭塞行MSCTA检查的患者19例,在ADW 4.3工作站采用Add Vessel技术对侧支循环行选择性血管重建。结果:19例共出现侧支血管93支,其中腹壁上动脉与腹壁下动脉19支;第11、12肋间动脉于腹壁上部与腹壁下动脉交通19支;第12肋间动脉与旋髂深动脉交通3支;双侧旋髂浅动脉交通19支;第4腰动脉与髂腰动脉交通20支,其中1例合并左侧第1腰动脉与骶外侧动脉交通1支;直肠上动脉与直肠下动脉交通3支;骶正中动脉与直肠下动脉交通1支;骶外侧动脉与旋髂深动脉交通8支。结论:AV技术显示血管具有选择性、整体感强及解剖细节清楚等特点,可为临床选择合理的治疗方案提供可靠依据。

Revisiting tumor angiogenesis:vessel co-option,vessel remodeling,and cancer cell-derived vasculature formation

Tumor growth and metastasis depend on the establishment of tumor vasculature to provide oxygen,nutrients,and other essential factors.The well-known vascular endothelial growth factor(VEGF) signaling is crucial for sprouting angiogenesis as well as recruitment of circulating progenitor endothelial cells to tumor vasculature,which has become therapeutic targets in clinical practice.However,the survival benefits gained from targeting VEGF signaling have been very limited,with the inevitable development of treatment resistance.In this article,we discuss the most recent findings and understanding on how solid tumors evade VEGF-targeted therapy,with a special focus on vessel co-option,vessel remodeling,and tumor cell-derived vasculature establishment.Vessel co-option may occur in tumors independently of sprouting angiogenesis,and sprouting angiogenesis is not always required for tumor growth.The differences between vessel-like structure and tubule-like structure formed by tumor cells are also introduced.The exploration of the underlying mechanisms of these alternative angiogenic approaches would not only widen our knowledge of tumor angiogenesis but also provide novel therapeutic targets for better controlling cancer growth and metastasis.

Experiments on the Resistance of a Large Transport Vessel Navigating in the Arctic Region in Pack Ice Conditions

In this study, we carried out model tests to investigate the ice failure process and the resistance experienced by a transport vessel navigating in the Arctic region in pack ice conditions. We tested different navigation velocities, ice plate sizes, and ice concentrations. During the tests, we closely observed several phenomena, including the modes of interaction of the ice ship and the moving and failure modes of ice. We also measured the vessel resistances under different conditions. The test results indicate that the navigation velocity is a significant determinant of the moving and failure modes of ice. Moreover, vessel resistance is remarkably dependent on the ice concentration and navigation velocity. The variances of the mean and maximum resistance are also compared and discussed in detail.

FVID: Fishing Vessel Type Identification Based on VMS Trajectories

Vessel Monitoring System(VMS) provides a new opportunity for quantified fishing research. Many approaches have been proposed to recognize fishing activities with VMS trajectories based on the types of fishing vessels. However, one research problem is still calling for solutions, how to identify the fishing vessel type based on only VMS trajectories. This problem is important because it requires the fishing vessel type as a preliminary to recognize fishing activities from VMS trajectories. This paper proposes fishing vessel type identification scheme(FVID) based only on VMS trajectories. FVID exploits feature engineering and machine learning schemes of XGBoost as its two key blocks and classifies fishing vessels into nine types. The dataset contains all the fishing vessel trajectories in the East China Sea in March 2017, including 10031 pre-registered fishing vessels and 1350 unregistered vessels of unknown types. In order to verify type identification accuracy, we first conduct a 4-fold cross-validation on the trajectories of registered fishing vessels. The classification accuracy is 95.42%. We then apply FVID to the unregistered fishing vessels to identify their types. After classifying the unregistered fishing vessel types, their fishing activities are further recognized based upon their types. At last, we calculate and compare the fishing density distribution in the East China Sea before and after applying the unregistered fishing vessels, confirming the importance of type identification of unregistered fishing vessels.

Retrospective evaluation of lymphatic and blood vessel invasion and Borrmann types in advanced proximal gastric cancer

BACKGROUND The Borrmann classification system is used to describe the macroscopic appearance of advanced gastric cancer,and Borrmann typeⅣdisease is independently associated with a poor prognosis.AIM To evaluate the prognostic significance of lymphatic and/or blood vessel invasion(LBVI)combined with the Borrmann type in advanced proximal gastric cancer(APGC).METHODS The clinicopathological and survival data of 440 patients with APGC who underwent curative surgery between 2005 and 2012 were retrospectively analyzed.RESULTS In these 440 patients,LBVI+status was associated with Borrmann typeⅣ,low histological grade,large tumor size,and advanced pT and pN status.The 5-year survival rate of LBVI+patients was significantly lower than that of LBVI– patients,although LBVI was not an independent prognostic factor in the multivariate analysis.No significant difference in the prognosis of patients with Borrmann typeⅢ/LBVI+disease and patients with Borrmann typeⅣdisease was observed.Therefore,we proposed a revised Borrmann typeⅣ(r-BorⅣ)as Borrmann typeⅢplus LBVI+,and found that r-BorⅣwas associated with poor prognosis in patients with APGC,which outweighed the prognostic significance of pT status.CONCLUSION LBVI is related to the prognosis of APGC,but is not an independent prognostic factor.LBVI status can be used to differentiate Borrmann typesⅢandⅣ,and the same approach can be used to treat r-BorⅣand Borrmann typeⅣ.

Point association analysis of vessel target detection with SAR, HFSWR and AIS

A space-borne synthetic aperture radar （SAR）, a high frequency surface wave radar （HFSWR）, and a ship automatic identification system （AIS） are the main remote sensors for vessel monitoring in a wide range. These three sensors have their own advantages and weaknesses, and they can complement each other in some situations. So it would improve the capability of vessel target detection to use multiple sensors including SAR, HFSWR, and A/S to identify non-cooperative vessel targets from the fusion results. During the fusion process of multiple sensors＇ detection results, point association is one of the key steps, and it can affect the accuracy of the data fusion and the efficiency of a non-cooperative target＇s recognition. This study investigated the point association analyses of vessel target detection under different conditions： space- borne SAR paired with AIS, as well as HFSWR, paired with AIS, and the characteristics of the SAR and the HFSWR and their capability of vessel target detection. Then a point association method of multiple sensors was proposed. Finally, the thresholds selection of key parameters in the points association （including range threshold, radial velocity threshold, and azimuth threshold） were investigated, and their influences on final association results were analyzed.

Electro-acupuncture at Conception and Governor vessels and transplantation of umbilical cord bloodderived mesenchymal stem cells for treating cerebral ischemia/reperfusion injury

Mesenchymal stem cell transplantation is a novel means of treating cerebral ischemia/reper- fusion, and can promote angiogenesis and neurological functional recovery. Acupuncture at Conception and Governor vessels also has positive effects as a treatment for cerebral ischemia/ reperfusion. Therefore, we hypothesized that electro-acupuncture at Conception and Governor vessels plus mesenchymal stem cell transplantation may have better therapeutic effects on the promotion of angiogenesis and recovery of neurological function than either treatment alone. In the present study, human umbilical cord blood-derived mesenchymal stem cells were isolated, cultured, identified and intracranially transplanted into the striatum and subcortex of rats at 24 hours following cerebral ischemia/reperfusion. Subsequently, rats were electro-acupunctured at Conception and Governor vessels at 24 hours after transplantation. Modified neurological severity scores and immunohistochemistry findings revealed that the combined interventions of electro-acupuncture and mesenchymal stem cell transplantation clearly improved neurological impairment and up-regulated vascular endothelial growth factor expression around the isch- emic focus. The combined intervention provided a better outcome than mesenchymal stem cell transplantation alone. These findings demonstrate that electro-acupuncture at Conception and Governor vessels and mesenchymal stem cell transplantation have synergetic effects on promot- ing neurological function recovery and angiogenesis in rats after cerebral ischemia/reperfusion.

WATER WAVES IN AN ELASTIC VESSEL

Linear and nonlinear analyses of water waves in an elastic vessel are carried out to study the dramatic phenomena of Dragon Wash as well as related controllable experiments. It is proposed that the capillary edge waves are generated by parametric resonance, which is shown to be a possible mechanism for both rectangular an circular vessels. For circular vessel, the normal geometric resonance is also operating, thus greatly. enhance the dramatic effect. The mechanism of nonlinear mode-mode interaction is proposed far the generation of axisymmetric low-frequency gravity waves by the high-frequency external excitation. A simple model system is studied numerically to demonstrate explicitly this interaction mechanism.

Robust Leader-Follower Formation Tracking Control of Multiple Underactuated Surface Vessels

This paper is concerned with the formation control problem of multiple underactuated surface vessels moving in a leader-follower formation. The formation is achieved by the follower to track a virtual target defined relative to the leader. A robust adaptive target tracking law is proposed by using neural network and backstepping techniques. The advantage of the proposed control scheme is that the uncertain nonlinear dynamics caused by Coriolis/centripetal forces, nonlinear damping, unmodeled hydrodynamics and disturbances from the environment can be compensated by on line learning. Based on Lyapunov analysis, the proposed controller guarantees the tracking errors converge to a small neighborhood of the origin. Simulation results demonstrate the effectiveness of the control strategy.

穿支皮瓣中choke vessels的新生过程研究及“血管体”概念

背景:穿支皮瓣是临床修复皮肤软组织缺损的常用方法,choke vessels作为穿支血管之间相互沟通的桥梁,在跨区穿支皮瓣成活方面起着重要作用。目的:对穿支皮瓣中choke vessels新生过程的研究进展作一综述。方法:计算机检索1984至2017年Pub Med、中国知网和中国生物医学文献数据库等数据库收录的关于穿支皮瓣和穿支皮瓣中choke vessels新生的基础研究、临床报道和研究进展文献,英文检索词为"perforator flap,perforator vessels,choke vessels,choke zone",中文检索词为"穿支皮瓣,穿支血管,闭塞血管,choke血管"。结果与结论:最终纳入文献51篇进行总结综述。穿支皮瓣在临床广泛应用于修复各种原因导致的皮肤软组织缺损。相邻穿支血管之间通过choke vessels进行吻合,跨区穿支皮瓣成活与choke vessels的扩张新生密切相关。choke vessels新生与血管新生机制可能存在重叠,缺血缺氧预处理和炎性环境可能促进choke vessels新生。

Load Bearing Capacity and Safety Analysis for Strain-hardening Austenitic Stainless Steel Pressure Vessels

By increasing the yield strengths of austenitic stainless steels for pressure vessels with strain hardening techniques,the elastic load bearing capacity of austenitic stainless steel pressure vessels can be significantly improved.Two kinds of strain hardening methods are often used for austenitic stainless steel pressure vessels：Avesta model for ambient temperature applications and Ardeform model for cryogenic temperature applications.Both methods are obtained from conventional design rules based on the linear elastic theory,and only consider the hardening effect from materials.Consequently this limits the applications of strain hardening techniques for austenitic stainless steel pressure vessels because of safety concerns.This paper investigates the effect of strain hardening on the load bearing capacity of austenitic stainless steel pressure vessels under large deformation,based on the elastic-plastic theory.Firstly,to understand the effect of strain hardening on material behavior,the plastic instability loads of a round tensile bar specimen are derived under two different loading paths and validated by experiments.Secondly,to investigate the effect of strain hardening on pressure vessels strength, the plastic instability pressure under strain hardening is derived and further validated by finite element simulations.Further,the safety margin of pressure vessels after strain hardening is analyzed by comparing the safety factor values calculated from bursting tests,finite element analyses,and standards.The researching results show that the load bearing capacity of pressure vessels at ambient temperature is independent of the loading history when the effects of both material strain hardening and structural deformation are considered.Finite element simulations and bursting tests results show that the minimum safety factor of austenitic stainless steel pressure vessels with 5% strain hardening is close to the recommended value for common pressure vessels specified in the European pressure vessel standard.The proposed study also shows that in the strain hardening design of austenitic stainless steel pressure vessels,the calculation for plastic instability pressure could use theoretical formula or finite element analyses based on geometrical dimensions and material property parameters before strain hardening,but a 5%strain should be employed as a design limit.The proposed research can be used for the strain hardening design of austenitic stainless steel pressure vessels safely.

THEORY OF WATER WAVES IN AN ELASTIC VESSEL

Recent experiments related to the Dragon Wash phenomena showed that axisymmetric capillary waves appear first from excitation, and circumferential capillary waves appear after increase of the excitation strength. Based on this new finding, a theory of parametric resonance is developed in detail to explain the on- set of the prominent circumferential capillary waves. Numerical computation is also carried out and the results agree generally with the experiments. Analysis and nu- merical computation are also presented to explain the generation of axisymmetric low-frequency gravity waves by tile high-frequency external excitation.