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关于有级变速拖拉机工作速度的合理挡数 被引量:1
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作者 周纪良 周天悦 《拖拉机与农用运输车》 北大核心 2002年第4期8-10,共3页
论述了拖拉机工作速度的合理挡数和各挡速度的设置,提出了变速箱最少挡数计算方法的建议、速度间的级比和速度排列方式,推荐了几种最佳的结构方案。
关键词 有级变速拖拉机 工作速度 合理挡数 有级变速箱 牵引阻力 功率利用
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歪斜托轮调窑歪斜托轮档娄和推导及实例
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作者 赵红霞 常松枝 《陕西建材》 1998年第6期24-25,共2页
本文推导出调窑所需歪斜托轮的挡数所承受的支反力占窑回转部分总载荷的30-36%,这一结论实践中得以验证。
关键词 回转窑 托轮 调整 歪斜托轮 挡数 水泥厂
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3D hydrodynamics involving multiple eccentric impellers in unbaffled cylindrical tank 被引量:6
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作者 Houari Ameur 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2016年第5期572-580,共9页
In this paper, the numerical predictions of 3D hydrodynamics and power consumption in a vessel stirred by mul- tiple eccentrically located impellers are presented. The vessel is a fiat-bottomed cylindrical one equippe... In this paper, the numerical predictions of 3D hydrodynamics and power consumption in a vessel stirred by mul- tiple eccentrically located impellers are presented. The vessel is a fiat-bottomed cylindrical one equipped with six-curved bladed impellers. Aqueous solutions of xanthan gum are used, which have a shear thinning behavior with yield stress. The influence of several parameters on the mixing efficiency has been investigated, namely: the stirring rate, fluid theology, impeller number and impeller clearance from the tank bottom. Our predicted results are compared with other experimental data and a satisfactory agreement is found. 展开更多
关键词 Computational fluid dynamics MIXING Non-Newtonian fluids Laminar flow Eccentric impeller
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Model Test and Numerical Analysis on Long-Term Mechanical Properties of Stepped Reinforced Retaining Wall 被引量:5
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作者 WANG Chengzhi LUAN Maotian ZHU Zeqi 《Transactions of Tianjin University》 EI CAS 2012年第1期62-68,共7页
Model tests and numerical analyses of stepped reinforced retaining wall were performed to investigate the effects of rheology of backfill and creep of geogrids on the long-term performance of the structure.The geogrid... Model tests and numerical analyses of stepped reinforced retaining wall were performed to investigate the effects of rheology of backfill and creep of geogrids on the long-term performance of the structure.The geogrid tensions,soil pressures,wall deformations and foundation pressure were measured during model construction and loading.A visco-elasto-plastic model and an empirical nonlinear visco-elastic model were utilized to simulate the stresses and deformations of geogrid-reinforced earth-retaining wall under long-term loads.By comparing test data with numerical results,it is shown that the foundation pressure distribution is nonlinear,and the lateral constraint of geogrids for backfill can cause a redistribution of foundation pressure.The curve of soil pressure is outside convex at each step initially,and it is close to the distribution for the case of vertical wall subsequently.The variation trend of geogrid tensions at different heights is obtained.Moreover,the failure mechanism and development mode of potential slip surface in retaining wall are proposed. 展开更多
关键词 model test GEOGRID stepped reintbrced retaining wall finite element method visco-elasto-plasticity model
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Pseudo-dynamic analysis of overturning stability of retaining wall 被引量:4
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作者 王奎华 马少俊 吴文兵 《Journal of Central South University》 SCIE EI CAS 2011年第6期2085-2090,共6页
A new method was presented to determine the safety factor of wall stability against overturning based on pseudo-dynamic approach. In this time-dependent method, the actual dynamic effect with variation of time and pro... A new method was presented to determine the safety factor of wall stability against overturning based on pseudo-dynamic approach. In this time-dependent method, the actual dynamic effect with variation of time and propagation of shear and primary wave velocities through the backfills was considered. Planar failure surface was considered behind the retaining wall. The results were compared with those obtained from Mononobe-Okabe theory. It is found that there is a higher value of safety factor by the present dynamic analysis. The effects of wall inclination, wall friction angle, soil friction angle and horizontal and vertical seismic coefficients on the overturning stability of retaining wall were investigated. The parametric study shows that both horizontal and vertical seismic accelerations have decreasing effect on the overturning stability of retaining wall. 展开更多
关键词 seismic active force pseudo-dynamic method EARTHQUAKE stability against overturning retaining wall
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Numerical investigation of radial inflow in the impeller rear cavity with and without baffle 被引量:6
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作者 LIU Guang DU Qiang +2 位作者 LIU Jun WANG Pei ZHU JunQiang 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2016年第3期456-467,共12页
In typical small engines, the cooling air for high pressure turbine (HPT) in a gas turbine engine is commonly bled off from the main flow at the tip of the centrifugal impeller. The pressurized air flow is drawn rad... In typical small engines, the cooling air for high pressure turbine (HPT) in a gas turbine engine is commonly bled off from the main flow at the tip of the centrifugal impeller. The pressurized air flow is drawn radially inwards through the impeller rear cavity. The centripetal air flow creates a strong vortex because of high inlet tangential velocity, which results in significant pressure losses. This not only restricts the mass flow rate, but also reduces the cooling air pressure for down-stream hot com- ponents. The present study is devoted to the numerical modeling of flow in an impeller rear cavity. The simulations are can'ied out with axisymmetric and 3-D sector models for various inlet swirl ratio ,80 (0-0.6), turbulent flow parameter 2-r (0.028-0,280) with and without baffle. The baffle is a thin plate attached to the stationary wall of the cavity, and is proved to be useful in re- ducing the pressure loss of centripetal flow in the impeller rear cavity in the current paper. Further flow details in impeller rear cavity with and without baffle are displayed using CFD techniques. The CFD results show that for any specified geometry, the outlet pressure coefficient of impeller rear cavity with or without baffle depends only on the inlet swirl ratio and turbulent flow parameter. Meanwhile, the outlet pressure coefficient of the cavity with baffle is indeed smaller than that of cavity without baffle, especially for the cases with high inlet swirl ratio. The suppression of the effect of centrifugal pumping and the mixing beween the main air which is downstream of the baffle and the recirculating flow of the vortex in the stationary cavity, which are caused by the use of baffle, are the underlying reasons that lead to the reduction of outlet pressure loss. 展开更多
关键词 impeller rear cavity de-swirling device BAFFLE Batchelor's Model Vortex Model
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Experimental study of GaN based blue light emitting diodes with a thin AlInN layer in front of the electron blocking layer 被引量:1
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作者 路纲 王波 葛运旺 《Optoelectronics Letters》 EI 2015年第4期248-251,共4页
The Ga N based blue light emitting diodes(LEDs) with a thin Al In N layer inserted in front of the electron blocking layer(EBL) are experimentally studied.It is found that inserting a thin EBL can improve the light ou... The Ga N based blue light emitting diodes(LEDs) with a thin Al In N layer inserted in front of the electron blocking layer(EBL) are experimentally studied.It is found that inserting a thin EBL can improve the light output power and reduce the efficiency droop compared with the conventional Al Ga N counterparts.Based on numerical simulation and analysis,the improvement on the electrical and optical characteristics is mainly attributed to the reduction of the electron leakage current,which increases the concentration of carriers in the quantum well(QW) when the thin Al In N layer is used. 展开更多
关键词 blocking inserted inserting attributed leakage thick crystalline nucleation lifetime Heidelberg
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