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Dynamic stabilization of plasma instability
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作者 S.Kawata T.Karino Y.J.Gu 《高功率激光科学与工程:英文版》 CAS CSCD 2019年第1期17-26,共10页
The paper presents a review of dynamic stabilization mechanisms for plasma instabilities. One of the dynamic stabilization mechanisms for plasma instability was proposed in the paper [Kawata, Phys. Plasmas 19, 024503(... The paper presents a review of dynamic stabilization mechanisms for plasma instabilities. One of the dynamic stabilization mechanisms for plasma instability was proposed in the paper [Kawata, Phys. Plasmas 19, 024503(2012)],based on a perturbation phase control. In general, instabilities emerge from the perturbations. Normally the perturbation phase is unknown, and so the instability growth rate is discussed. However, if the perturbation phase is known, the instability growth can be controlled by a superimposition of perturbations imposed actively. Based on this mechanism we present the application results of the dynamic stabilization mechanism to the Rayleigh–Taylor instability(RTI) and to the filamentation instability as typical examples in this paper. On the other hand, in the paper [Boris, Comments Plasma Phys. Control. Fusion 3, 1(1977)] another mechanism was proposed to stabilize RTI, and was realized by the pulse train or the laser intensity modulation in laser inertial fusion [Betti et al., Phys. Rev. Lett. 71, 3131(1993)]. In this latter mechanism, an oscillating strong force is applied to modify the basic equation, and consequently the new stabilization window is created. Originally the latter was proposed by Kapitza. We review the two stabilization mechanisms, and present the application results of the former dynamic stabilization mechanism. 展开更多
关键词 DYNAMIC INSTABILITY STABILIZATION FILAMENTATION INSTABILITY PLASMA INSTABILITY RAYLEIGH-TAYLOR INSTABILITY STABILIZATION of INSTABILITY
Mitigating self-excited flame pulsating and thermoacoustic oscillations using perforated liners
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作者 Dan Zhao Ephraim Gutmark Arne Reinecke 《科学通报:英文版》 SCIE EI CSCD 2019年第13期941-952,共12页
Open-loop control of self-excited flame pulsating oscillations and thermo-acoustic instability is considered in this work.The performance of the control strategy is numerically evaluated in a 2 D Rij ke-type combustor... Open-loop control of self-excited flame pulsating oscillations and thermo-acoustic instability is considered in this work.The performance of the control strategy is numerically evaluated in a 2 D Rij ke-type combustor with a perfo rated pipe implemented.It is found that approximately 38 dB sound pressure level(SPL)reduction can be achieved by actively tuning the cooling flow through the perforated pipe.Furthermore,the vorticity-induced damping performance is contributing to the breaking up of flame-acoustics coupling.However,the shedding of vortices is not uniformly distributed along the perforated pipe.To apply the control strategy in practice and to validate the findings,experimental studies are performed on a customerdesigned Rij ke-type combustor with a perfo rated liner implemented.To mimic practical engines,a cooling flow generated by a centrifugal pump is provided to pass through the perforated pipe.Properly tuning the cooling flow rate is found to lead to the unstable combustor being successfully stabilized.SPL is red uced by approximately 35 dB at ω1/2π≈245 Hz,and harmonic thermoacoustic modes are completely attenuating.Further study is conducted by suddenly re moving the perforated pipe section.The combustion system is found to be associated with not only classical thermo-acoustic limit cycle oscillations with a dominant mode at 2.45 × 102 Hz,but also beating oscillations at 1.4 × 1 00 Hz.It is revealed that increasing acoustic losses by implementing the perforated pipe is another critical mechanism contributing to attenuating flame pulsating instability.The present work opens up an applicable means to attenuate both selfexcited high-frequency thermoacoustic and low-frequency flame pulsating oscillations. 展开更多
关键词 FLAME BEATING Combustion INSTABILITY Thermo-acoustic INSTABILITY Thermal-diffusive INSTABILITY Perforated pipe ACOUSTIC LOSSES
A review on the flow instability of nanofluids 预览
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作者 Jianzhong LIN Hailin YANG 《应用数学和力学:英文版》 SCIE EI CSCD 2019年第9期1227-1238,共12页
Nanofluid flow occurs in extensive applications, and hence has received widespread attention. The transition of nanofluids from laminar to turbulent flow is an important issue because of the differences in pressure dr... Nanofluid flow occurs in extensive applications, and hence has received widespread attention. The transition of nanofluids from laminar to turbulent flow is an important issue because of the differences in pressure drop and heat transfer between laminar and turbulent flow. Nanofluids will become unstable when they depart from the thermal equilibrium or dynamic equilibrium state. This paper conducts a brief review of research on the flow instability of nanofluids, including hydrodynamic instability and thermal instability. Some open questions on the subject are also identified. 展开更多
关键词 NANOFLUID THERMAL INSTABILITY HYDRODYNAMIC INSTABILITY REVIEW
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Charney’s Model—the Renowned Prototype of Baroclinic Instability—Is Barotropically Unstable As Well 预览
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作者 Yuan-Bing ZHAO X.San LIANG 《大气科学进展:英文版》 SCIE CAS CSCD 2019年第7期733-752,共20页
The Charney model is reexamined using a new mathematical tool, the multiscale window transform(MWT), and the MWT-based localized multiscale energetics analysis developed by Liang and Robinson to deal with realistic ge... The Charney model is reexamined using a new mathematical tool, the multiscale window transform(MWT), and the MWT-based localized multiscale energetics analysis developed by Liang and Robinson to deal with realistic geophysical fluid flow processes. Traditionally, though this model has been taken as a prototype of baroclinic instability, it actually undergoes a mixed one. While baroclinic instability explains the bottom-trapped feature of the perturbation, the second extreme center in the perturbation field can only be explained by a new barotropic instability when the Charney–Green number γ 1, which takes place throughout the fluid column, and is maximized at a height where its baroclinic counterpart stops functioning.The giving way of the baroclinic instability to a barotropic one at this height corresponds well to the rectification of the tilting found on the maps of perturbation velocity and pressure. Also established in this study is the relative importance of barotropic instability to baroclinic instability in terms of γ. When γ 1, barotropic instability is negligible and hence the system can be viewed as purely baroclinic;when γ 1, however, barotropic and baroclinic instabilities are of the same order;in fact, barotropic instability can be even stronger. The implication of these results has been discussed in linking them to real atmospheric processes. 展开更多
关键词 Charney’s MODEL multiscale window transform CANONICAL transfer BAROCLINIC INSTABILITY BAROTROPIC INSTABILITY
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The intrinsic nonlinear multiscale interactions among the mean flow, low frequency variability and mesoscale eddies in the Kuroshio region
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作者 Yang YANG X.San LIANG 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2019年第3期595-608,共14页
Using a new functional analysis tool, multiscale window transform(MWT), and the MWT-based localized multiscale energetics analysis and canonical transfer theory, this study reconstructs the Kuroshio system on three sc... Using a new functional analysis tool, multiscale window transform(MWT), and the MWT-based localized multiscale energetics analysis and canonical transfer theory, this study reconstructs the Kuroshio system on three scale windows, namely,the mean flow window, the interannual-scale(low-frequency) window, and the transient eddy window, and investigates the climatological characteristics of the intricate nonlinear interactions among these windows. Significant upscale energy transfer is observed east of Taiwan, where the mean Kuroshio current extracts kinetic energy from both the interannual and eddy windows.It is found that the canonical transfer from the interannual variability is an intrinsic source that drives the eddy activities in this region. The multiscale variabilities of the Kuroshio in the East China Sea(ECS) are mainly controlled by the interaction between the mean flow and the eddies.The mean flow undergoes mixed instabilities(i.e., both barotropic and baroclinic instabilities) in the southern ECS, while it is barotropically stable but baroclinically unstable to the north. The multiscale interactions are found to be most intense south of Japan, where strong mixed instabilities occur;both the canonical transfers from the mean flow and the interannual scale are important mechanisms to fuel the eddies. It is also found that the interannual-scale energy mainly comes from the barotropically unstable jet, rather than the upscale energy transfer from the high frequency eddies. 展开更多
关键词 KUROSHIO Multiscale window transform CANONICAL transfer Multiscale ENERGETICS analysis Multiscale interaction BAROTROPIC INSTABILITY BAROCLINIC INSTABILITY
Secondary instability of separated shear layers
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作者 Zhiyin YANG 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第1期37-44,共8页
The process through which a laminar flow undergoes transition to turbulence is of great fundamental and practical interest. Such a process is hugely complex as there are many diverse routes for a laminar flow to becom... The process through which a laminar flow undergoes transition to turbulence is of great fundamental and practical interest. Such a process is hugely complex as there are many diverse routes for a laminar flow to become turbulent flow. The transition process is usually initiated by flow instabilities-a primary instability stage followed by a secondary instability stage. This forms a rational framework for the early stage of a transition process and it is crucially important to understand the physics of instabilities leading to turbulence. This article reviews the results of studies on secondary instability of separated shear layers in separation bubbles and summaries the current status of our understanding in this area. 展开更多
关键词 Primary INSTABILITY SECONDARY INSTABILITY SEPARATED SHEAR LAYERS Separation BUBBLES Transition
Glycerophospholipids pathways and chromosomal instability in gastric cancer: Global lipidomics analysis 预览
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作者 Cheng-Yu Hung Ta-Sen Yeh +7 位作者 Cheng-Kun Tsai Ren-Chin Wu Ying-Chieh Lai Meng-Han Chiang Kuan-Ying Lu Chia-Ni Lin Mei-Ling Cheng Gigin Lin 《世界胃肠肿瘤学杂志:英文版(电子版)》 CAS 2019年第3期181-194,共14页
BACKGROUND Based on the breakthrough of genomics analysis, The Cancer Genome Atlas Research Group recently proposed an integrative genomic analysis, dividing gastric cancer(GC) into four subtypes, characterized by the... BACKGROUND Based on the breakthrough of genomics analysis, The Cancer Genome Atlas Research Group recently proposed an integrative genomic analysis, dividing gastric cancer(GC) into four subtypes, characterized by the chromosomal instability(CIN) status. However, the CIN status of GC is still vaguely characterized and lacking the valuable easy-to-use CIN markers to diagnosis in molecular and histological detection.AIM To explore the associations of CIN with downstream lipidomics profiles.METHODS We collected cancerous and noncancerous tissue samples from 18 patients with GC;the samples were divided into CIN and non-CIN types based on the system of The Cancer Genome Atlas Research Group and 409 sequenced oncogenes and tumor suppressor genes. We identified the lipidomics profiles of the GC samples and samples of their adjacent noncancerous tissues by using liquid chromatography–mass spectrometry. Furthermore, we selected leading metabolites based on variable importance in projection scores of > 1.0 and P <0.05.RESULTS Twelve men and six women participated in this study;the participants had a median age of 67.5 years(range, 52–87 years) and were divided into CIN(n = 9)and non-CIN(n = 9) groups. The GC samples exhibited distinct profiles of lysophosphocholine, phosphocholine, phosphatidylethanolamine,phosphatidylinositol, phosphoserine, sphingomyelin, ceramide, and triglycerides compared with their adjacent noncancerous tissues. The glycerophospholipid levels(phosphocholine, phosphatidylethanolamine, and phosphatidylinositol)were 1.4-to 2.3-times higher in the CIN group compared with the non-CIN group(P < 0.05). Alterations in the glycerolipid and glycerophospholipid pathways indicated progression of GC toward CIN.CONCLUSION The lipidomics profiles of GC samples were distinct from those of their adjacent noncancerous tissues. CIN status of GC is primarily associated with downstream lipidomics in the glycerophospholipid pathway. 展开更多
关键词 CHROMOSOMAL INSTABILITY Gastric cancer GLYCEROPHOSPHOLIPIDS Metabolomics LIPIDOMICS profile
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基于可靠度理论的混凝土重力坝失事概率计算 预览
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作者 郑昊尧 金先龙 +1 位作者 林绍清 杨士龚 《山西建筑》 2019年第12期167-169,共3页
基于可靠度理论对混凝土重力坝失稳失效概率进行计算,完成混凝土重力坝的风险评估,该方法可为混凝土重力坝风险评估提供一定的技术支撑。
关键词 可靠度 混凝土重力坝 失稳 失效
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钢管拱安装施工过程结构受力特性分析 预览
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作者 高喆 《上海公路》 2019年第2期75-78,M0005共5页
针对位于曲线上的某新建铁路(66+132+66)m连续梁拱桥,根据先梁后拱的施工方案,对中跨132 m钢管拱安装的支架结构、拱肋的稳定、应力和支座反力等展开计算分析,研究结果显示:此类安装支架设计安全可靠;施工过程中拱肋应力呈对称分布,拱... 针对位于曲线上的某新建铁路(66+132+66)m连续梁拱桥,根据先梁后拱的施工方案,对中跨132 m钢管拱安装的支架结构、拱肋的稳定、应力和支座反力等展开计算分析,研究结果显示:此类安装支架设计安全可靠;施工过程中拱肋应力呈对称分布,拱肋各关注截面顶、底部应力实测值和计算值基本吻合;桥跨结构失稳的一阶模态以拱肋横向弯曲为主,稳定系数为37;成桥时主梁边墩的内外侧支座反力相差约4.6%,中墩的内外侧支座反力相差约7.4%。 展开更多
关键词 连续梁拱桥 拱肋 支架 稳定 实测值 支座反力
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Investigation of convergent Richtmyer–Meshkov instability at tin/xenon interface with pulsed magnetic driven imploding
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作者 张绍龙 刘伟 +6 位作者 王贵林 章征伟 孙奇志 张朝辉 李军 池原 张南川 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第4期247-253,共7页
The Richtmyer–Meshkov instability at the interface of solid state tin material and xenon gases under cylinder geometry is studied in this paper. The experiments were conducted at FP-1 facility in Institute of Fluid P... The Richtmyer–Meshkov instability at the interface of solid state tin material and xenon gases under cylinder geometry is studied in this paper. The experiments were conducted at FP-1 facility in Institute of Fluid Physics, China Academy of Engineering Physics(CAEP). The FP-1 facility is a pulsed power driver which could generate high amplitude magnetic field to drive metal liner imploding. Convergent shock wave was generated by impacting a magnetic-driven aluminium liner onto a inner mounted tin liner. The convergent evolution of the disturbance pre-machined onto the tin liner’s inner surface was diagnosed by x-radiography. The spike amplitudes were derived from x-ray frames and were compared with linear theory.An analytical model containing material strength effect was derived and matched well to the experimental results. This sensibility of the disturbance evolution to material strength property shines light to the application of Richtmyer–Meshkov instability to infer material strength. 展开更多
关键词 Richtmyer–Meshkov INSTABILITY PULSED power DRIVER CONVERGENT shock wave
Study. movement characteristics,"re-stabilization" conditions. overlying key stratum structure after losing stability 预览
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作者 Nan Li 《探索-地质与矿业研究》 2019年第1期18-25,共8页
Engineering practices, phenomenon, step subsidence. roof caused.Sliding destabilisation. key stratum structures without support crushing frequently exists. hence a mechanical model. key stratum structure after sliding... Engineering practices, phenomenon, step subsidence. roof caused.Sliding destabilisation. key stratum structures without support crushing frequently exists. hence a mechanical model. key stratum structure after sliding instability. established, movement characteristics,"re-stabilization" conditions. key stratum structure after losing stability. An-alyzed..: Show, roof subsidence caused. instability. key stratum structure may not always exceed. threshold, crushes supports. alternatively, unstable block. key stratum may stop sliding. stability. rotation squeezing or touching. falling rocks be-fore crushing. support. two "re-stabilization" conditions. revealed. under certain conditions maintaining rational mining height within support capability or increasing support resistance. make. unstaBle block. rotation squeezing stability. put forward so as. prevent crushing. support. 展开更多
关键词 Key STRATUM SLIDING instability Re-stabilization Support CRUSHING UNSTABLE Block
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复合材料杆塔横担的设计及承载能力研究 预览
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作者 徐海潮 王志强 +2 位作者 杨垂玮 赵雪灵 兰志文 《电力勘测设计》 2019年第6期35-41,共7页
复合材料横担是杆塔重要的组成部分,起到连接输电体系挂线的作用。复合材料横担常规布置方式有“三拉一压”、“两拉两压”等结构形式,主要由绝缘压管和绝缘拉棒组成,采用“三拉一压”横担布置方案通过有限元分析对复合横担进行设计及优... 复合材料横担是杆塔重要的组成部分,起到连接输电体系挂线的作用。复合材料横担常规布置方式有“三拉一压”、“两拉两压”等结构形式,主要由绝缘压管和绝缘拉棒组成,采用“三拉一压”横担布置方案通过有限元分析对复合横担进行设计及优化,选择合理的型号。该结构形式的复合横担由三根拉管和一根压管组成,其中绝缘压管的失稳是结构设计中的一个主要问题。该文从理论出发,提出一种变截面形式的绝缘压管,通过能量法推导其稳定承载能力,并通过有限元计算分析绝缘压管的承载力变化规律,最后与普通等截面绝缘压管的承载能力进行对比,研究成果能够为复合材料横担的设计提供借鉴。 展开更多
关键词 复合材料 横担 失稳 变截面形式 压管
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零工经济是一种劳资双赢的新型用工关系吗
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作者 谢富胜 吴越 《经济学家》 CSSCI 北大核心 2019年第6期5-14,共10页
借助能够广泛采集和匹配信息的数字平台,零工经济实现了众包劳动和按需服务的大规模组织,是一种符合资本弹性积累要求而产生的新型用工关系。在零工经济中,劳动者可以自由选择工作时间,但需要接受"独立承包商"的地位并付出社... 借助能够广泛采集和匹配信息的数字平台,零工经济实现了众包劳动和按需服务的大规模组织,是一种符合资本弹性积累要求而产生的新型用工关系。在零工经济中,劳动者可以自由选择工作时间,但需要接受"独立承包商"的地位并付出社会保障缺失的代价。零工经济为高技能劳动者和兼职劳动者提供了更灵活的工作机会和较高的总收入。低技能全职零工劳动者则迫于生活和竞争的压力主动选择工作时间的延长和工作强度的增大,日益面临收入和工作日程的不稳定化。只有考虑多方利益对零工经济进行规制和引导,才能使应用新技术的零工经济实现劳资双赢。 展开更多
关键词 零工经济 弹性积累 不稳定化 数字平台
斜压大气中地形和δ效应下的Rossby波的不稳定性 预览
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作者 张秀杰 刘少夏 宋健 《内蒙古工业大学学报:自然科学版》 2019年第1期8-13,共6页
使用多重尺度方法对斜压Rossby波在地形和δ效应共同作用下的不稳定性进行了研究,讨论了基本流和地形、δ效应对Rossby波结构的影响.结果表明,东西方向和南北方向地形对Rossby波的不稳定性和相速度以及能量传播有很大差异.
关键词 ROSSBY波 基本流 地形 不稳定性 δ效应
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襟翼翼尖涡控制飞机尾流机制实验研究
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作者 朱睿 陈子煜 +4 位作者 李尚 谭雅勤 傅向向 鲍锋 刘志荣 《推进技术》 EI CAS CSCD 北大核心 2019年第4期768-779,共12页
为了研究襟翼小涡与主翼尖涡相交不稳定性触发条件,采用矩形机翼模型产生一对翼尖涡,同时在机翼上安装不同宽度及攻角的襟翼,对35个翼展下诱发R-L(Rayleigh-Ludwig)不稳定性的最佳涡系参数组合进行了研究。结果表明:通过水槽流动显示实... 为了研究襟翼小涡与主翼尖涡相交不稳定性触发条件,采用矩形机翼模型产生一对翼尖涡,同时在机翼上安装不同宽度及攻角的襟翼,对35个翼展下诱发R-L(Rayleigh-Ludwig)不稳定性的最佳涡系参数组合进行了研究。结果表明:通过水槽流动显示实验发现,单主翼尾涡在第35个翼展处未发生明显变化,能量衰减缓慢;加装襟翼后尾流不稳定性被触发,衰减效果明显,在一定范围内尾涡能量衰减值随着襟翼攻角的增大而增大;环量统计半径Rd=50mm时,对主翼尖涡环量进行PIV(Particle Image Velocimetry)分析时发现,当主翼攻角α=8°,襟翼攻角β=28°,襟翼宽度b=55mm,来流速度V=0.5m/s时尾涡能量消散最快,主翼尖涡环量在第35个翼展时衰减为第一个翼展的28%;证实通过安装合适的襟翼可以有效地控制飞机尾流,加速其破裂和消散。 展开更多
关键词 翼尖涡 不稳定性 流动显示 粒子图像测速 环量
壁面润湿性对微细通道内R141b流动沸腾不稳定性的影响 预览
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作者 罗小平 廖政标 +1 位作者 周建阳 张霖 《化工进展》 EI CAS CSCD 北大核心 2019年第2期752-760,共9页
为了探究壁面润湿性对制冷剂R141b流动沸腾不稳定性的影响,设计微细通道流动沸腾实验平台,制备3种不同润湿性的矩形微细通道,其壁面接触角分别为62.3°、接近0°和158.7°。以R141b为实验工质,在截面宽×高为1mm×... 为了探究壁面润湿性对制冷剂R141b流动沸腾不稳定性的影响,设计微细通道流动沸腾实验平台,制备3种不同润湿性的矩形微细通道,其壁面接触角分别为62.3°、接近0°和158.7°。以R141b为实验工质,在截面宽×高为1mm×2mm的矩形微细通道内进行流动沸腾换热实验,研究了沿程测点压力波动情况以及影响进出口总压降波动的因素,最后对总压降波动信号进行Hurst指数分析,结果表明:微细通道沿程测点波动方差最大的位置正处于沸腾起始点(ONB)附近,热流密度的减小以及质量通量的增大均会使沸腾起始点推后;进出口总压降波动受热流密度、质量通量和壁面润湿性的影响,相同工况下,热流密度增大和质量通量的减小都会引起系统不稳定性增强,超疏水表面微细通道的总压降波动方差均比其他两种表面的大,是波动方差最小的超亲水表面的1.35~1.84倍;利用Hurst指数分析,表明系统具有混沌现象,超疏水表面微细通道的Hurst指数最大,表现出更强烈的不稳定性。 展开更多
关键词 微细通道 润湿性 不稳定性 HURST指数
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Observational evidences of wave excitation and inverse cascade in a distant Earth foreshock region
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作者 Jiansen HE Die DUAN +2 位作者 Xingyu ZHU Limei YAN Linghua WANG 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2019年第4期619-630,共12页
The foreshock with nascent plasma turbulence is regarded as a fascinating region to understand basic plasma physical processes, e.g., wave-particle interactions as well as wave-wave couplings. Although there have been... The foreshock with nascent plasma turbulence is regarded as a fascinating region to understand basic plasma physical processes, e.g., wave-particle interactions as well as wave-wave couplings. Although there have been plenty of intensive studies on this topic, some key clues about the physical processes still lack observations. A relatively comprehensive case study with some new observations is presented in this work based on the WIND spacecraft observations. In this case, upstream energetic protons were drifting at tens of Alfvén speed with respect to the background plasma protons. When looking at the magnetic wave activities, we find the co-existence of high-frequency(0.1-0.5 Hz) large-amplitude right-hand polarized(RHP) waves and lowfrequency(0.02-0.1 Hz) small-amplitude left-hand polarized(LHP) waves in the spacecraft(SC) frame. The observed anticorrelation between magnetic and velocity fluctuations along with the sunward magnetic field direction indicates that the lowfrequency LHP waves in the SC frame are in fact the sunward upstream RHP Alfvénic waves in the solar wind frame. This new observation corroborates the applicability of theories about plasma non-resonance instability and inverse cascade to the foreshock region, where the downstream high-frequency RHP parent waves are excited by the upstream energetic protons through non-resonance instability and the low-frequency RHP daughter waves are generated by the parent waves due to nonlinear parametric instability. Furthermore, enhanced downstream energetic proton fluxes are inferred to result from scattering of the upstream protons by the nascent turbulent fluctuations. Therefore, some critical clues about the newborn turbulence in the foreshock are provided in this work. 展开更多
关键词 Solar WIND FORESHOCK Wave-particle interaction PARAMETRIC INSTABILITY
综放工作面推近断层过程中顶板稳定性力学分析
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作者 师皓宇 田多 +1 位作者 石建军 侯沣峻 《辽宁工程技术大学学报:自然科学版》 CAS 北大核心 2019年第1期7-13,共7页
为研究综放工作面推进顶板过程中的顶板力学结构,以中煤平朔井工三矿34201综放工作面过断层为工程原型,采用理论分析方法,推导了工作面推近断层面时基本顶和直接顶的力学平衡方程和力矩平衡方程,研究了基本顶和直接顶发生压垮支护系统... 为研究综放工作面推进顶板过程中的顶板力学结构,以中煤平朔井工三矿34201综放工作面过断层为工程原型,采用理论分析方法,推导了工作面推近断层面时基本顶和直接顶的力学平衡方程和力矩平衡方程,研究了基本顶和直接顶发生压垮支护系统和转动失稳的判据,定性分析了影响基本顶和直接顶稳定的主要因素.依据基本顶和直接顶失稳判据进行分析可知:基本顶和直接顶更易沿断层面转动失稳,基本顶的悬臂长度应随工作面推近断层而减小,当工作面距离断层5m时,基本顶悬臂长度应小于1.43m,否则基本顶可沿断层面上一点转动.这为控制基本顶和直接顶转动失稳提供了的力学依据. 展开更多
关键词 断层 顶板 力学结构 失稳 悬臂长度
接管弯矩与外压作用下薄壁圆筒的失稳分析 预览
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作者 方小里 张福君 《锅炉制造》 2019年第4期56-58,共3页
本文采用考虑初始几何缺陷的弹塑性应力分析方法对某带薄壁圆筒进行了非线性失稳分析,结果表明:开孔接管大大降低了薄壁圆筒失稳临界载荷;随着接管弯矩的增大,圆筒临界失稳载荷有一定程度减低,并且圆筒的临界变形有整体失稳波形向接管... 本文采用考虑初始几何缺陷的弹塑性应力分析方法对某带薄壁圆筒进行了非线性失稳分析,结果表明:开孔接管大大降低了薄壁圆筒失稳临界载荷;随着接管弯矩的增大,圆筒临界失稳载荷有一定程度减低,并且圆筒的临界变形有整体失稳波形向接管局部失稳转变。 展开更多
关键词 接管弯矩 薄壁圆筒 外压 失稳
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Finite-thickness effect of the fluids on bubbles and spikes in Richtmyer–Meshkov instability for arbitrary Atwood numbers
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作者 刘万海 于长平 +3 位作者 王裴 付峥 王丽丽 陈玉莲 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第2期9-15,共7页
This paper investigates the finite-thickness effect of two superimposed fluids on bubbles and spikes in Richtmyer–Meshkov instability(RMI) for arbitrary Atwood numbers by using the method of the small parameter expan... This paper investigates the finite-thickness effect of two superimposed fluids on bubbles and spikes in Richtmyer–Meshkov instability(RMI) for arbitrary Atwood numbers by using the method of the small parameter expansion up to the second order. When the thickness of the two fluids tends to be infinity, our results can reproduce the classical results where RMI happens at the interface separating two semi-infinity-thickness fluids of different densities. It is found that the thickness has a large influence on the amplitude evolution of bubbles and spikes compared with those in classical RMI. Based on the thickness relationship of the two fluids, the thickness effect on bubbles and spikes for four cases is discussed. The thickness encourages(or reduces)the growth of bubbles or spikes, depending on not only Atwood number, but also the relationship of the thickness ratio of the heavy and light fluids, which is explicitly determined in this paper. 展开更多
关键词 Richtmyer–Meshkov INSTABILITY BUBBLES and SPIKES finite-thickness
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