期刊文献+
共找到7,716篇文章
< 1 2 250 >
每页显示 20 50 100
On the Lebesgue Integral and the Lebesgue Measure: Mathematical Applications in Some Sectors of Chern-Simons Theory and Yang-Mills Gauge Theory and Mathematical Connections with Some Sectors of String Theory and Number Theory
1
作者 Michele Nardelli 《Journal of Modern Physics》 2025年第1期93-132,共40页
In this paper, in Section 1, we have described some equations and theorems concerning the Lebesgue integral and the Lebesgue measure. In Section 2, we have described the possible mathematical applications, of Lebesgue... In this paper, in Section 1, we have described some equations and theorems concerning the Lebesgue integral and the Lebesgue measure. In Section 2, we have described the possible mathematical applications, of Lebesgue integration, in some equations concerning various sectors of Chern-Simons theory and Yang-Mills gauge theory, precisely the two dimensional quantum Yang-Mills theory. In conclusion, in Section 3, we have described also the possible mathematical connections with some sectors of String Theory and Number Theory, principally with some equations concerning the Ramanujan’s modular equations that are related to the physical vibrations of the bosonic strings and of the superstrings, some Ramanujan’s identities concerning π and the zeta strings. 展开更多
关键词 Lebesgue Integral Chern-Simons Theory Yang-Mills Gauge Theory string Theory Number Theory
在线阅读 下载PDF
Numerical investigation of wellbore damage due to drill string lateral vibration
2
作者 Hadi Haghgouei Anders Nermoen Alexandre Lavrov 《Journal of Rock Mechanics and Geotechnical Engineering》 2025年第3期1287-1301,共15页
During drilling operations,cyclic loading is exerted on the wellbore wall by the vibrations of the drill string.This loading could lead to rock fatigue,which in turn might result in wellbore failure.In this study,a nu... During drilling operations,cyclic loading is exerted on the wellbore wall by the vibrations of the drill string.This loading could lead to rock fatigue,which in turn might result in wellbore failure.In this study,a numerical model is developed to simulate the effects of repeated loading on rock fatigue and failure.The simulation is based on an elasto-plastic constitutive model coupled with a damage mechanics approach,which allows us to examine the wellbore instability due to drill string vibrations.The model is verified with the existing data in the literature related to experiments on impact of a steel ball against a curved wall.The findings indicate that cyclic loading increases the development of plastic strain around the wellbore significantly compared to static conditions,promoting rock fatigue.Furthermore,the cyclic loading expands the radius of the yielded zone substantially,a critical factor for maintaining wellbore integrity.The proposed model can be used to evaluate the wellbore stability under repetitive loading caused by the drill string action. 展开更多
关键词 Wellbore stability Damage mechanics Fatigue modeling Drill string vibration
在线阅读 下载PDF
Prediction of Injection-Production Ratio with BP Neural Network
3
作者 袁爱武 郑晓松 王东城 《Petroleum Science》 SCIE CAS CSCD 2004年第4期62-65,共4页
Injection of water to enhance oil production is commonplace, and improvements in understanding the process are economically important. This study examines predictive models of the injection-to-production ratio. First... Injection of water to enhance oil production is commonplace, and improvements in understanding the process are economically important. This study examines predictive models of the injection-to-production ratio. Firstly, the error between the fitting and actual injection-production ratio is calculated with such methods as the injection-production ratio and water-oil ratio method, the material balance method, the multiple regression method, the gray theory GM (1,1) model and the back-propogation (BP) neural network method by computer applications in this paper. The relative average errors calculated are respectively 1.67%, 1.08%, 19.2%, 1.38% and 0.88%. Secondly, the reasons for the errors from different prediction methods are analyzed theoretically, indicating that the prediction precision of the BP neural network method is high, and that it has a better self-adaptability, so that it can reflect the internal relationship between the injection-production ratio and the influencing factors. Therefore, the BP neural network method is suitable to the prediction of injection-production ratio. 展开更多
关键词 injection-production ratio (IPR) BP neural network gray theory PREDICTION
在线阅读 下载PDF
Synchronous injection-production energy replenishment for a horizontal well in an ultra-low permeability sandstone reservoir: A case study of Changqing oilfield in Ordos Basin, NW China 被引量:1
4
作者 WANG Jing LIU Jungang +7 位作者 LI Zhaoguo LI Hongchang ZHANG Jiaosheng LI Wenqing ZHANG Yuanli PING Yi YANG Huanying WANG Ping 《Petroleum Exploration and Development》 2020年第4期827-835,共9页
It is difficult to build an effective water flooding displacement pressure system in the middle section of a horizontal well in an ultra-low permeability sandstone reservoir.To solve this problem,this study proposes t... It is difficult to build an effective water flooding displacement pressure system in the middle section of a horizontal well in an ultra-low permeability sandstone reservoir.To solve this problem,this study proposes to use packers,sealing cannula and other tools in the same horizontal well to inject water in some fractures and produce oil from other fractures.This new energy supplement method forms a segmental synchronous injection-production system in a horizontal well.The method can reduce the distance between the injection end and the production end,and quickly establish an effective displacement system.Changing the displacement between wells to displacement between horizontal well sections,and point water flooding to linear uniform water flooding,the method can enhance water sweeping volume and shorten waterflooding response period.The research shows that:(1)In the synchronous injection and production of horizontal well in an ultra-low-permeability sandstone reservoir,the water injection section should select the section where the natural fractures and artificial fractures are in the same direction or the section with no natural fractures,and the space between two sections should be 60?80 m.(2)In addition to controlling injection pressure,periodic water injection can be taken to reduce the risk of re-opening and growth of natural fractures or formation fracture caused by the gradual increase of water injection pressure with water injection going on.(3)Field tests have verified that this method can effectively improve the output of single well and achieve good economic benefits,so it can be widely used in the development of ultra-low permeability sandstone reservoirs. 展开更多
关键词 ultra-low permeability reservoir sandstone reservoir horizontal well staged fracturing synchronous injection-production intersegment displacement development effect
在线阅读 下载PDF
Detachable string magnetically controlled capsule endoscopy for the noninvasive diagnosis of esophageal diseases:A prospective,blind clinical study 被引量:1
5
作者 Yan-Ling Yang Huang-Wen Qin +5 位作者 Zhao-Yu Chen Hui-Ning Fan Yi Yu Wei Da Jin-Shui Zhu Jing Zhang 《World Journal of Gastroenterology》 SCIE CAS 2024年第9期1121-1131,共11页
BACKGROUND Traditional esophagogastroduodenoscopy(EGD),an invasive examination method,can cause discomfort and pain in patients.In contrast,magnetically controlled capsule endoscopy(MCE),a noninvasive method,is being ... BACKGROUND Traditional esophagogastroduodenoscopy(EGD),an invasive examination method,can cause discomfort and pain in patients.In contrast,magnetically controlled capsule endoscopy(MCE),a noninvasive method,is being applied for the detection of stomach and small intestinal diseases,but its application in treating esophageal diseases is not widespread.AIM To evaluate the safety and efficacy of detachable string MCE(ds-MCE)for the diagnosis of esophageal diseases.METHODS Fifty patients who had been diagnosed with esophageal diseases were pros-pectively recruited for this clinical study and underwent ds-MCE and conven-tional EGD.The primary endpoints included the sensitivity,specificity,positive predictive value,negative predictive value,and diagnostic accuracy of ds-MCE for patients with esophageal diseases.The secondary endpoints consisted of visualizing the esophageal and dentate lines,as well as the subjects'tolerance of the procedure.RESULTS Using EGD as the gold standard,the sensitivity,specificity,positive predictive value,negative predictive value,and diagnostic accuracy of ds-MCE for esophageal disease detection were 85.71%,86.21%,81.82%,89.29%,and 86%,respectively.ds-MCE was more comfortable and convenient than EGD was,with 80%of patients feeling that ds-MCE examination was very comfortable or comfortable and 50%of patients believing that detachable string v examination was very convenient.CONCLUSION This study revealed that ds-MCE has the same diagnostic effects as traditional EGD for esophageal diseases and is more comfortable and convenient than EGD,providing a novel noninvasive method for treating esophageal diseases. 展开更多
关键词 Clinical trial Detachable string magnetically controlled capsule endoscopy ESOPHAGOGASTRODUODENOSCOPY Noninvasive diagnosis Esophageal diseases
在线阅读 下载PDF
Injection-production parameters optimization research SAGD production stage
6
作者 Fu Yu Qu Wenchi Song Xin 《International Journal of Technology Management》 2014年第9期119-120,共2页
Steam assisted gravity drainage (SAGD) technology has been industrialized popularization and application in our country, according to the characteristics of Xing group I SAGD experimental zone in liaohe oilfield, SA... Steam assisted gravity drainage (SAGD) technology has been industrialized popularization and application in our country, according to the characteristics of Xing group I SAGD experimental zone in liaohe oilfield, SAGD production stage injection-production parameters such as the operating pressure, Sub - Cool control, steam injection rate, steam dryness, production factor are studied and selected. 展开更多
关键词 injection-production parameters PRESSURE steam injection rate steam quality production factor
在线阅读 下载PDF
Practice of Effectively Tapping the Potential of Grass-roots Injection-production System
7
作者 LIUWeidong 《外文科技期刊数据库(文摘版)工程技术》 2022年第8期148-152,共5页
The process of enterprise development is a management process of finding responsibility, releasing responsibility and implementing responsibility. The production technology department of our unit is mainly responsible... The process of enterprise development is a management process of finding responsibility, releasing responsibility and implementing responsibility. The production technology department of our unit is mainly responsible for controlling injection and production indicators, eliminating system shortcomings, preventing and controlling safety risks, and improving system quality and efficiency. How to tap, release and enhance potential under the new performance appraisal policy is our responsibility. Based on the concept of "the simplest management, the most advanced technology, the most economical cost and the most efficient management", this paper has carried out beneficial practice in exploring and effectively tapping the potential of grass-roots injection-production system, releasing and effectively improving the technical potential of injection-production system. 展开更多
关键词 MINING potential of grass-roots injection-production system method of work
在线阅读 下载PDF
Elementary Fermions: Strings, Planck Constant, Preons and Hypergluons
8
作者 Doron Kwiat 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第1期82-100,共19页
Using real fields instead of complex ones, it is suggested here that the fermions are pairs of coupled strings with an internal tension. The interaction between the two coupled strings is due to an exchange mechanism ... Using real fields instead of complex ones, it is suggested here that the fermions are pairs of coupled strings with an internal tension. The interaction between the two coupled strings is due to an exchange mechanism which is proportional to Planck’s constant. This may be the result of two massless bosons (hypergluons) coupled by a preon (prequark) exchange. It also gives a physical explanation to the origin of the Planck constant, and origin of spin. 展开更多
关键词 FERMIONS Preons Hypergluons strings Real Fields Planck Constant INTERFERENCE SPIN
在线阅读 下载PDF
Stringy Phenomenology with Preon Models
9
作者 Risto Raitio 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第1期1-7,共7页
We compare, following Pati, global symmetries, our topological supersymmetric preon model with the heterotic E<sub>8</sub> × E<sub>8</sub> string theory. We include Pati’s supergravity ba... We compare, following Pati, global symmetries, our topological supersymmetric preon model with the heterotic E<sub>8</sub> × E<sub>8</sub> string theory. We include Pati’s supergravity based preon model in this work and compare the preon interactions of his model to ours. Based on preon-string symmetry comparison and preon phenomenological results, we conclude that the fundamental particles are likely preons rather than standard model particles. . 展开更多
关键词 Topological Field Theory Chern-Simons Theory SUPERSYMMETRY string Theory
在线阅读 下载PDF
Towards 6D Little String Theory of Particles
10
作者 Risto Raitio 《Journal of High Energy Physics, Gravitation and Cosmology》 CAS 2024年第2期546-561,共16页
A model for particles based on preons in chiral, vector and tensor/graviton supermultiplets of unbroken global supersymmetry is engineered. The framework of the model is little string theory. Phenomenological predicti... A model for particles based on preons in chiral, vector and tensor/graviton supermultiplets of unbroken global supersymmetry is engineered. The framework of the model is little string theory. Phenomenological predictions are discussed. 展开更多
关键词 Standard Model Composite Models SUPERSYMMETRY Little string Theory T-DUALITY HOLOGRAPHY
在线阅读 下载PDF
Study on Injection-Production System Adjustment of Fault Block Reservoir Based on Equilibrium Displacement
11
作者 Ming Yang Cunliang Chen +2 位作者 Yu Wang Xiaohui Wu Dong Ma 《Open Journal of Yangtze Oil and Gas》 2020年第2期35-45,共11页
This paper proposed a method of injection-production system adjustment to solve the problem that the water flooding effect was restricted because of the horizontal and vertical contradictions during the development pr... This paper proposed a method of injection-production system adjustment to solve the problem that the water flooding effect was restricted because of the horizontal and vertical contradictions during the development process of fault block reservoirs. Considering the heterogeneity of reservoir, the Buckley-Leverett water flooding theory was applied to establish the relationship between the recovery and cumulative water injection. In order to achieve the goal of vertically balanced recovery of each section, the calculation method of vertical sectional injection allocation was proposed. The planar triangular seepage unit was assumed and sweep coefficients of different oil-water distribution patterns were characterized using multi-flow tube method. In order to balance and maximize the plane sweep coefficient, the calculation method of plane production system optimization was obtained. Then the injection-production system stereoscopic adjustment method based on equilibrium displacement was proposed with vertical sectional injection allocation and plane production system optimization. This method was applied to injection and production adjustment of BZ oilfield in southern Bohai. The effect of water control and oil increase was obvious. This method can greatly improve the effect of water flooding of offshore fault block reservoirs with the adjustment of injection-production system. 展开更多
关键词 Fault Block Reservoir Equilibrium Displacement Vertical Sectional Injection Allocation Planar Production System Optimization Adjustment of injection-production System
在线阅读 下载PDF
Investigating the expression profiles of cysteine string proteins(CSPs)in cochlear tissue
12
作者 Shili Zhang Caiji Wang +1 位作者 Yuehua Qiao Xi Shi 《Journal of Otology》 CAS CSCD 2024年第4期193-199,共7页
Objective:This study aims to explore the expression patterns of cysteine string protein alpha(CSPα)and cysteine string protein beta(CSPβ)in the mammalian inner ear,with an emphasis on their temporal dynamics during ... Objective:This study aims to explore the expression patterns of cysteine string protein alpha(CSPα)and cysteine string protein beta(CSPβ)in the mammalian inner ear,with an emphasis on their temporal dynamics during the developmental stages of C57BL/6 mice.Methods:We utilized immunofluorescence staining to assess the localization and distribution of CSPαand CSPβwithin the inner ears of C57BL/6 mice and miniature pigs.Additionally,this method facilitated the investigation of their temporal expression profiles.Results:In adult C57BL/6 mice and miniature pigs,CSPαand CSPβwere identified in the cytoplasm of inner hair cells and spiral ganglion cells,yet were absent in outer hair cells.Both proteins were found to colocalize with Ctbp2 on the basal side of the cytoplasm in inner hair cells’basilar membrane.Expression of CSPαwas observed at the nerve fiber termini at the basilar membrane’s base of inner and outer hair cells 10 days postnatally in C57BL/6 mice.Notably,expression of both CSPαand CSPβin the cytoplasm of inner hair cells emerged on the 12th day post-birth,aligning with the timeline for registering cochlear potentials.The expression levels of both proteins increased with age,but were consistently absent in outer hair cells.Contrastingly,expression of CSPαand CSPβwas present in the cytoplasm of inner hair cells in miniature pigs as early as one day post-birth,yet remained absent in the three rows of outer hair cells.Conclusion:CSPαand CSPβexhibit predominant and specific expression in inner hair cells and spiral ganglion cells.A unique expression pattern was observed for CSPα,which was also present at the nerve fiber endings of both inner and outer hair cells.The developmental expression trajectory of CSPαand CSPβin mouse inner hair cells is characterized by an initial absence,followed by a gradual increase.Moreover,the timing of expression onset between mice and miniature pigs indicates distinct temporal dynamics,suggesting a potential role in auditory development. 展开更多
关键词 Cysteine string protein CSPα CSPβ Miniature pig C57BL/6 mouse
在线阅读 下载PDF
Edward Witten: The father of modern string theory
13
作者 孙启禄 《疯狂英语(新读写)》 2024年第12期27-30,75,76,共6页
Edward Witten has been described as“the most brilliant physicist of his generation”,and some even compare him to Isaac Newton.A deeply original and dedicated theoretical physicist,Witten's primary focus is strin... Edward Witten has been described as“the most brilliant physicist of his generation”,and some even compare him to Isaac Newton.A deeply original and dedicated theoretical physicist,Witten's primary focus is string theory—a“theory of everything”that proposes the universe's fundamental components are curves,or“strings”arranged in loops.in loops.He has been a leading advocate and influential contributor in this field,famously stating,“It was very clear that if I didn't spend my life concentrating on string theory,I would simply be missing my life's calling.” 展开更多
关键词 THEORY simply string
在线阅读 下载PDF
分簇射孔管串泵送排量模型及影响因素分析
14
作者 柳军 袁明健 杜智刚 《中国海上油气》 北大核心 2025年第2期198-209,共12页
针对非常规油气开采过程中分簇射孔管串下入泵送排量问题,考虑井眼轨迹、井筒约束、变径工具串、管串变形以及沿程压降等作用的影响,采用微元法建立了分簇射孔管串泵送排量模型。借助2口实例井现场作业数据,验证了本文所建模型的正确性... 针对非常规油气开采过程中分簇射孔管串下入泵送排量问题,考虑井眼轨迹、井筒约束、变径工具串、管串变形以及沿程压降等作用的影响,采用微元法建立了分簇射孔管串泵送排量模型。借助2口实例井现场作业数据,验证了本文所建模型的正确性。基于现场数据,分析了“4簇射孔枪+1桥塞”管串在M3井中的泵送排量。基于此,探究了分簇数量、射孔枪规格及下入速度对泵送排量的影响,结果表明分簇数量、射孔枪规格的增加会提高管串下入的摩擦力,导致下入困难,下入速度的增加会降低整个射孔过程效率,因此在现场作业时应当同时考虑效率和安全作业。研究成果可为现场泵送射孔管串下入作业参数优选和操作提供有效的分析方法和理论指导。 展开更多
关键词 管串变形 工具串变径 泵送排量 影响因素 泵送射孔
在线阅读 下载PDF
充填射孔枪的射孔液压力脉动及管柱应力分析
15
作者 窦益华 饶一伍 +3 位作者 李明飞 张伟 朱松青 梁经纬 《石油机械》 北大核心 2025年第4期56-63,共8页
射孔液充填射孔枪时的负压使射孔段管柱产生很大的下曳力,影响管柱和封隔器中心管的强度安全,但负压的量化一直是难点。建立射孔液压力脉动数值分析模型,分析射孔液充填射孔枪的压力脉动和负压及负压下的管柱安全。研究结果表明:16孔/m... 射孔液充填射孔枪时的负压使射孔段管柱产生很大的下曳力,影响管柱和封隔器中心管的强度安全,但负压的量化一直是难点。建立射孔液压力脉动数值分析模型,分析射孔液充填射孔枪的压力脉动和负压及负压下的管柱安全。研究结果表明:16孔/m、10 mm孔径,射孔液压力在1 ms达到最大值226.70 MPa,5 ms达到最小值24.80 MPa,随后做振幅减小的往复波动;孔密(16孔/m)不变,8、10、12 mm孔径时,最小压力分别为26.25、24.80、22.79 MPa,压差分别为214.23、201.9、189.2 MPa,说明孔径与负压呈负相关,最小降低到22.79 MPa;孔径10 mm不变,孔密为16、20、24孔/m时,最小压力分别为24.80、24.19、23.23 MPa,最大压差分别为201.9、211.81、215.19 MPa,说明孔密与负压呈负相关,最小降低到23.23 MPa。根据负压和鼓胀效应,得到了射孔段管柱和封隔器中心管的安全系数为1.43和1.24,说明射孔负压引起的下曳力可能是引发封隔器中心管损伤的主要因素。研究结果可为射孔段管柱安全强度分析提供新思路。 展开更多
关键词 射孔参数 射孔液 气液耦合 压力脉动 负压 管柱强度安全
在线阅读 下载PDF
储气库生产管柱的气固冲蚀性能
16
作者 李明星 刘广胜 +3 位作者 王娜 朱方辉 李文升 付安庆 《腐蚀与防护》 北大核心 2025年第2期66-72,共7页
结合榆3×储气库的注采工况,构建了气固冲蚀预测模型,研究了采气量、采气压力、颗粒属性等生产参数对冲蚀速率的影响规律,针对N80油管分析了发生不同程度冲蚀风险的极限生产工况。结果表明:在榆3×储气库预设采气指标范围内,最... 结合榆3×储气库的注采工况,构建了气固冲蚀预测模型,研究了采气量、采气压力、颗粒属性等生产参数对冲蚀速率的影响规律,针对N80油管分析了发生不同程度冲蚀风险的极限生产工况。结果表明:在榆3×储气库预设采气指标范围内,最大冲蚀速率随采气量的增大而增大;采气压力的增加会一定程度上降低管柱的冲蚀程度;冲蚀程度随出砂量的增加呈现线性增加趋势,颗粒直径的增大会导致冲蚀速率的增大,而颗粒球度的减小会导致冲蚀速率的增大。基于预测模型,建立了N80油管的临界生产参数图版,以实现基于现场易获取参数的冲蚀风险评估。 展开更多
关键词 储气库 注采管柱 气固冲蚀 临界生产参数 冲蚀风险评估
在线阅读 下载PDF
环空多级压裂工具串冲蚀磨损成因分析
17
作者 刘巨保 许靖扬 +3 位作者 刘玉喜 杨明 刘欢 黄茜 《石油机械》 北大核心 2025年第3期94-101,共8页
针对水平井连续管环空多级压裂中,喷枪及其上部工具均出现不同程度的冲蚀磨损和失效问题,采用数值模拟方法,依据ø139.7 mm(5.5 in)套管内连续管环空压裂工艺和工具结构参数,建立了压裂液颗粒流和工具冲蚀的数值模型及计算方法;通... 针对水平井连续管环空多级压裂中,喷枪及其上部工具均出现不同程度的冲蚀磨损和失效问题,采用数值模拟方法,依据ø139.7 mm(5.5 in)套管内连续管环空压裂工艺和工具结构参数,建立了压裂液颗粒流和工具冲蚀的数值模型及计算方法;通过正交试验设计了工具串窜动、管内流速、环空流速、含砂体积分数以及地层破裂压力5因素5水平的25种计算工况。数值模拟结果表明:喷枪上部工具出现冲蚀磨损的主要因素是工具串窜动,在工具串未窜动时最大冲蚀速率出现在喷嘴下方附近,在工具串窜动时最大冲蚀速率出现在距离喷嘴约为窜动位移的上部工具区域;未窜动时的最大冲蚀速率值明显高于窜动时的结果,并随着环空流道间隙的减小而增大。所得结果可为工具串的冲蚀磨损分析及控制提供理论依据和分析方法。 展开更多
关键词 水平井多级分段压裂 压裂工具 冲蚀磨损 数值模拟 工具串窜动
在线阅读 下载PDF
四分跨对称双集中阻尼弦系统的振动特性
18
作者 郑罡 曾广榕 +2 位作者 张永顺 杨钰峰 王保權 《科学技术与工程》 北大核心 2025年第1期30-36,共7页
带有集中黏滞阻尼的张紧弦系统在力学模型上属于混杂动力学系统,为满足工程应用一般采用近似方法求解其本征问题。为进一步明确该系统振动特性,以两项集中阻尼对称布置于四等分跨的阻尼弦系统作为基础研究对象,并对其复本征值进行解析... 带有集中黏滞阻尼的张紧弦系统在力学模型上属于混杂动力学系统,为满足工程应用一般采用近似方法求解其本征问题。为进一步明确该系统振动特性,以两项集中阻尼对称布置于四等分跨的阻尼弦系统作为基础研究对象,并对其复本征值进行解析求解。推导系统的复频率方程和本征函数表达式,将超越函数形式的复频率方程换元处理为代数形式,利用代数方程给出系统复本征值的显式解。分析系统复本征值的结构和性质,讨论振动特性随阻尼系数的变化规律。结果表明:系统本征解可归为3个解支,在同一解支内本征值实部(相反数即为衰减率)不随系统运动阶次而改变,本征值虚部(即频率)则随运动阶次以4π为周期依次递增;各解支所对应的衰减率曲线均随阻尼系数呈先递增、后递减的趋势,且在衰减率曲线连续变化的阻尼区间内,系统各阶运动的频率相等。 展开更多
关键词 集中阻尼 张紧弦 动力特性 复本征值 复模态
在线阅读 下载PDF
多自由度体系的动力放大系数解析研究
19
作者 张超 周桢干 +2 位作者 赖志超 付馨迪 杨晓强 《振动工程学报》 北大核心 2025年第3期550-557,共8页
在结构动力冲击响应分析中,通常采用动力放大系数(DAF)简化计算结构的动力响应。但是,目前工程结构中对DAF的取值还存在争议。针对此问题,本文推导了多自由度(MDOF)体系的DAF解析表达式,分析了DAF大于2.0的前提条件;分别通过单自由度(SD... 在结构动力冲击响应分析中,通常采用动力放大系数(DAF)简化计算结构的动力响应。但是,目前工程结构中对DAF的取值还存在争议。针对此问题,本文推导了多自由度(MDOF)体系的DAF解析表达式,分析了DAF大于2.0的前提条件;分别通过单自由度(SDOF)体系和MDOF体系算例模型验证了解析表达式的准确性,解释了MDOF体系的DAF大于2.0的原因。基于所提出的DAF解析表达式分析了张弦梁剩余结构在断索冲击作用下的DAF分布规律。分析结果表明:当某一阶模态振型的分量与静力响应值反向时,张弦梁的DAF可能会大于2.0;即使在有阻尼情况下,张弦梁的DAF也可能会大于2.0。 展开更多
关键词 多自由度体系 张弦梁 动力放大系数 断索冲击
在线阅读 下载PDF
多层压裂充填施工管柱侧向出流孔冲蚀损坏机理及结构优化
20
作者 徐凤祥 刘洪刚 +4 位作者 王浩宇 张伦 徐海珍 董长银 李经纬 《中国海上油气》 北大核心 2025年第2期220-230,共11页
海上油田多层压裂充填施工管柱的侧向出流孔的冲蚀损坏问题较为严重,显著影响管柱使用寿命。针对出流孔冲蚀机理不明确且缺乏结构优化依据的问题,使用现场实际施工材料和泵注条件,开展了管柱出流孔冲蚀损坏模拟实验。结果表明:砂比与排... 海上油田多层压裂充填施工管柱的侧向出流孔的冲蚀损坏问题较为严重,显著影响管柱使用寿命。针对出流孔冲蚀机理不明确且缺乏结构优化依据的问题,使用现场实际施工材料和泵注条件,开展了管柱出流孔冲蚀损坏模拟实验。结果表明:砂比与排量对冲蚀速率影响最大,黏度影响相对较小;出流孔间的返溅作用加速了冲蚀过程,在排量22 m^(3)/h、砂比80%条件下,出流孔平均冲蚀速率达到0.05 g/h,说明携砂液砂比与排量以及不同出流孔之间的返溅作用是影响出流孔侧向冲蚀的重要原因。基于冲蚀损坏模拟实验结果并结合金属表面微观分析,构建了冲蚀损坏程度评价方法,并提出尖端侧向切削机理、端面侧向切削机理及颗粒返溅正面啃噬机理三种冲蚀破坏机理。基于冲蚀损坏机理与规律,提出两项结构优化方案,即增厚保护套2.5 mm及出流孔倾斜角度改为38.42°。优化实验结果表明,优化后方案可延长出流孔使用寿命约30%。本研究为非常规低渗透储层的水力压裂增产改造,以及中高渗储层的多层压裂充填防砂施工管柱结构优化提供了直接依据。 展开更多
关键词 多层压裂充填防砂管柱 侧向出流口 冲蚀损坏机理 影响因素 结构优化
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部