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1.
不可压各向异性超弹性材料中的空穴生成 总被引：3，自引：0，他引：3
The cavitation problem in a solid sphere composed of an incompressible anisotropic hyper-elastic material under a univroms radial tensile dead load was examined.A new analytical solution was obtained.The stress contruibutions were given and the jumping and concentration of stresses were discussed.The stability of solutions and the effect of the degree of ainsotropy of the material were analyzed. 相似文献
2.
The analyses of finite deformation and stress for a hyperelastic rectangular plate with some voids under an uniaxial extension were conducted. The governing differential equations were given from the incompressibility condition of the material. The solution was approximately obtained from the minimum potential energy principle. The growth of voids was discussed. One can see that an initial central circular-cylinder void becomes an elliptic-cylinder void, but an initial non-centeral circular-cylinder void becomes an elliptic-like cylinder void and the center of void has a shift. The stress distributions along the edges of voids were given and the phenomenon of stress concentration was observed. The influences of the distribution manner and size of voids, as well as the distance between them on the growth of voids were analyzed. 相似文献
3.
Cyclic electron flow around photosystem I is required for adaptation to high temperature in a subtropical forest tree, Ficus concinna 总被引：1，自引：0，他引：1
Song-heng Jin Xue-qin Li Jun-yan Hu Jun-gang Wang 《Journal of Zhejiang University. Science. B》2009,10(10):784-790
Dissipation mechanisms of excess photon energy under high-temperature stress were studied in a subtropical forest tree seedling, Ficus concinna. Net CO2 assimilation rate decreased to 16% of the control after 20 of high-temperature stress, and thus the absorption of photon energy exceeded the energy required for CO2 assimilation. The efficiency of excitation energy capture by open photosystem Ⅱ (PSII) reaction centres (Fv'/Fm') at moderate irradiauce, photochemical quenching (qp), and the quantum yield of PSII electron transport (φPSII) were significantly lower after high-temperature stress. Nevertheless, non-photochemical quenching (qHP) and energy-dependent quenching (qE) were significantly higher under such conditions. The post-irradiation transient of chlorophyll (Chl) fluorescence significantly increased after the turnoff of the actinic light (AL), and this increase was considerably higher in the 39 ℃-grown seedlings than in the 30 ℃-grown ones. The increased post-irradiation fluorescence points to enhanced cyclic electron transport around PSI under high growth temperature conditions, thus helping to dissipate excess photon energy non-radiatively. 相似文献
4.
在声发射试验系统上,进行了花岗岩声发射实验,获得了静载下花岗岩破坏的声发射规律。结果表明,在加载初期,出现了一定量的声发射信号,声发射计数最大达到2 000,这对应着岩石初始裂纹的闭合段;随着应力继续增大,声发射能量增大量较小,声发射计数逐步增大至峰值,这对应着岩石弹性段;岩石进入损伤阶段后,声发射能量迅速增大,在应力最高点附近,声发射能量达到峰值,而声发射计数却下降至较低值,这种低频大试件往往意味着结构的破坏。 相似文献
5.
Numerical investigation of cavitating flow behind the cone of a poppet valve in water hydraulic system 总被引：2，自引：0，他引：2
Computational Fluid Dynamics (CFD) simulations of cavitating flow through water hydraulic poppet valves were performed using
advanced RNGk-epsilon turbulence model. The flow was turbulent, incompressible and unsteady, for Reynolds numbers greater than 43000. The
working fluid was water, and the structure of the valve was simplified as a two dimensional axisymmetric geometrical model.
Flow field visualization was numerically achieved. The effects of inlet velocity, outlet pressure, opening size as well as
poppet angle on cavitation intensity in the poppet valve were numerically investigated. Experimental flow visualization was
conducted to capture cavitation images near the orifice in the poppet valve with 30° poppet angle using high speed video camera.
The binary cavitating flow field distribution obtained from digital processing of the original cavitation image showed a good
agreement with the numerical result.
Project supported by the National Natural Science Foundation of China (No. 59835160) and Scientific Research Foundation for
Returned Overseas Chinese Scholars, State Education Ministry of China (No. 50175097) 相似文献
6.
冲击过程中能量匹配分析 总被引：1，自引：0，他引：1
颜祥山 《贵州教育学院学报》2001,12(2):16-17
简论了冲击过程中采用应力波方法分析能量匹配问题 ,得出 :冲击机械中入射应力波如满足理想波形时 ,从冲击对象反射回来的反射应力波能量达最小 ,冲击机械的能效达到最大值 相似文献
7.
In view of the present situation of low cavitation performance of deep-sea mining slurry pump, the effect of solid phase on the cavitation performance of deep-sea mining pump is analyzed theoretically. The relationship between gas and liquid phases are established by cavitation nucleon theory and mass energy equation as well as solid phase and liquid phase, and then we explored the relationship between gas phase and solid phase. The results show that the critical bubble radius and solid-phase concentration flow rate during the cavitation can be related to the liquid pressure. Eq. (19) show that the larger the solid particle concentration and the solid phase flow, the earlier the cavitation will occur, and pump anti-cavitation performance will decline. 相似文献
8.
前期已经对某电动汽车进行基于能量利用率的传动比设计,设计出自动变速器传动方案及其尺寸。本文采用Solidworks软件建立箱体结构模型,并以Solidworks Simulation对箱体前盖和后盖分别进行有限元分析,得出最大应力值及出现位置。结果表明,所设计的自动变速器既满足能量利用率最优又符合静强度要求。 相似文献
9.
A novel energy-regenerative active suspension (NEAS) system was designed to solve the problem of low energy recovery efficiency caused by frequent alternation of energy-recovery mode and active-control mode in a traditional energy-regenerative active suspension (TEAS) system. The energy recovery and active control could be implemented simultaneously in the NEAS. The transforming processes and the corresponding computational formulas of power conversion in the NEAS were provided. The simulation results show that the performances of energy recovery of the NEAS are improved, and the self-sustaining of power supply for the NEAS can be realized. 相似文献
10.
ABSTRACTThis paper presents a revised learning progression for the energy concept and initial findings on diverse progressions among subgroups of sample students. The revised learning progression describes how students progress towards an understanding of the energy concept along two progress variables identified from previous studies – key ideas about energy and levels of conceptual development. To assess students understanding with respect to the revised learning progression, we created a specific instrument, the Energy Concept Progression Assessment (ECPA) based on previous work on assessing students’ understanding of energy. After iteratively refining the instrument in two pilot studies, the ECPA was administered to a total of 4550 students (Grades 8–12) from schools in two districts in a major city in Mainland China. Rasch analysis was used to examine the validity of the revised learning progression and explore factors explaining different progressions. Our results confirm the validity of the four conceptual development levels. In addition, we found that although following a similar progression pattern, students’ progression rate was significantly influenced by environmental factors such as school type. In the discussion of our findings, we address the non-linear and complex nature of students’ progression in understanding energy. We conclude with illuminating our research's implication for curriculum design and energy teaching. 相似文献
11.
12.
基于势能驻值原理和广义坐标法原理推导出考虑截面畸变效应的梁单元刚度矩阵.根据此梁单元刚度矩阵,编制了计算薄壁钢箱梁结构的有限元程序,且此程序可以考虑截面畸变效应和扭转效应.运用自编程序,分析横隔板间距对薄壁钢箱梁受力性能的影响.通过数值计算,得出布置横隔板对畸变正应力的影响最大,对弯曲正应力的影响很小.畸变荷载作用下,只有当横隔板布置间距小到一定数值时,薄壁箱梁的畸变正应力才会减小.最后,引入畸变翘曲影响系数γ,简化了薄壁箱形梁纵向正应力的计算方法.当横隔板布置间距L与薄壁箱梁横截面最大尺寸H的比值小于2时,畸变翘曲影响系数γ趋于1,表明薄壁箱形梁的畸变正应力趋于零,可以忽略畸变效应的影响. 相似文献
13.
马丽芹 《临沂师范学院学报》2009,31(3):59-61
对大学物理教材中波的能流密度的定义提出了新看法,探讨了在机械波教学中如何讲授半波损失和驻波不传播能量的问题,并对半波损失和驻波能量做了简单的推导,其目的在于使学生容易理解． 相似文献
14.
顺昌县小城镇住宅小区示范工程电气系统优化设计 总被引：1，自引：0，他引：1
郑志 《福建工程学院学报》2004,2(2):235-238
通过对工程设计实践的总结，力求探索一条符合福建地域特点的小城镇住宅小区电气系统设计的模范道路。具有针对性地制定了包括：开放式系统设计、节约能源、建立社区信息网络在内的优化目标。从总体规划上强调系统的整体性，在分项子系统设计中建立可拓展空间，将节能理念渗透到系统各个细节，并特另4强调其开放性、合理性和可操作性。 相似文献
15.
本文探讨了变频调速恒压供水系统,该系统主要由变频器进行压力调节。变频器作为系统控制的核心部件,经过内置PID进行运算,比对压力传感器的反馈信号,实现闭环自动调节恒压变量供水。经过比较改造前后的实际效果,运行结果表明该系统具有压力稳定、结构简单、工作可靠等特点,节能效果明显。 相似文献
16.
俄罗斯是一个能源大国。但它目前的能源情况是：产量严重滑坡，市场非常混乱，俄罗斯成了世界能源利用率最低的国家之一。造成这一局面的原因主要在于，俄罗斯向私有制转型后，由于法制上的纰漏，政府官员播身一变，成了各类能源寡头。他们大肆抢摊国家能源制高点，导致能源严重流失；此外，俄罗斯虽然巳向市场经济转型，但由于能源寡头排斥和打击外商投资，因此，实际上俄罗新的能源业并没有对外开放，俄政府无法有效地利用外资开发能源。俄罗斯能源的前景取决于新政府怎样解决寡头对能源的垄断问题。 相似文献
18.
给出带电系统的静电能的三种表达式．根据自由电荷与束缚电荷的静电势能及相互作用和介质极化过程能量储存在介质中，把有介质存在时的带电系统的能量分成若干项，并加以讨论。 相似文献
19.
John O. Towler 《The Journal of environmental education》2013,44(1):56-58
A measurement scale has been developed to assess secondary students’ energy literacy—a citizenship understanding of energy that includes cognitive as well as affective and behavioral items. Instrument development procedures followed psychometric principles from educational and social psychology research. Initial exploration of the measure yielded promising results: internal consistencies for the cognitive, affective, and behavioral subscales, measured by Cronbach's α, ranged from 0.75 to 0.83; average discrimination indices ranged from 0.27 to 0.46. The instrument's validity was supported with contrasted-groups and developmental-age progression comparisons, as well as factor analyses. The energy literacy questionnaire provides an opportunity to measure baseline levels of energy literacy and to assess broader impacts of educational interventions. 相似文献
20.
郭建军 《廊坊师范学院学报(自然科学版)》2009,9(4):63-64
通过数学推导对静电场中所涉及到的静电能、电场能、自能和互能之间的能量关系进行量化分析,揭示了各种能量之间的内在联系。 相似文献