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11.
本文采用粒子追踪理论对水平管中粒子流动状态进行了数值模拟.文中提出了一种新的粒子碰撞模型,并忽略粒子的旋转和扬力,仅考虑气流阻力和重力对粒子的影响,在输送量为9.13×10~3kg/s,混合比约0.3的条件下,通过数值计算得知:由于粒子间的碰撞,使得异径粒子的速度趋向平均化;粒子间的碰撞是粒子悬浮的原因之一;粒子的浓度沿管轴向是随时间而发生变化的. 相似文献
12.
Quenching with gases rather than oil or other liquid media has the advantages of reducing the risks concerning health and environment, while simultaneously homogenizing the quenching results and minimizing distortion due to a wide range of possible process parameter variations and the pure convective heat transfer. In this contribution, a coupled solution for increasing homogenization of quenching results within high pressure gas quenching will be presented. In the first stage, an experimental test facility was set up for flow investigations and in the second stage a numerical simulation model was generated. The numerical and experimental results of the flow through the chamber were compared for several boundary conditions. Finally, after complete verification of the simulation, the model may be used to assist in parameter variation for optimization of homogeneous high pressure gas quenching. 相似文献
13.
A parametric interpolator with confined chord errors, acceleration and deceleration for NC machining 总被引:6,自引:0,他引:6
Tsehaw Yong Author Vitae Author Vitae 《Computer aided design》2003,35(13):1249-1259
Parametric interpolation has many advantages over linear interpolation in machining curves. Real time parametric interpolation research so far has addressed achieving a uniform feed rate, confined chord errors and jerk limited trajectory planning. However, simultaneous consideration of confined chord errors that respect the acceleration and deceleration capabilities of the machine has not been attempted. In this paper, the offline detection of feed rate sensitive corners is proposed. The velocity profile in these zones is planned so that chord errors are satisfied while simultaneously accommodating the machine's acceleration and deceleration limits. Outside the zone of the feed rate sensitive corners, the feed rate is planned using the Taylor approximation. Simulation results indicate that the offline detection of feed rate sensitive corners improves parametric interpolation. For real time interpolation, the parametric curve information can be augmented with the detected feed rate sensitive corners that are stored in 2×2 matrices. 相似文献
14.
Ken Mattsson 《Journal of scientific computing》2003,18(1):133-153
Four different methods of imposing boundary conditions for the linear advection-diffusion equation and a linear hyperbolic system are considered. The methods are analyzed using the energy method and the Laplace transform technique. Numerical calculations are done, considering in particular the case when the initial data and boundary data are inconsistent. 相似文献
15.
Influence of electroosmotic treatment on the hydro-mechanical behaviour of clayey silts: preliminary experimental results 总被引:1,自引:0,他引:1
Laura Gabrieli Cristina Jommi Guido Musso Enrique Romero 《Journal of Applied Electrochemistry》2008,38(7):1043-1051
Preliminary results of an investigation focused on the influence of electrokinetic treatment on the mechanical and hydraulic
behaviour of clayey soils are presented. The experimental programme aims at providing a contribution to the sustainability
of contaminant extraction or containment via electroosmosis. Changes in the hydraulic and mechanical properties of two illitic
clayey soils, subjected to a DC electric field, were investigated. Samples of the two soils were subjected to electrokinetic
filtration, for different periods of time, and under different constant loads. Afterwards, they were tested under one-dimensional
compression to detect changes in stiffness and hydraulic conductivity due to the electrical treatment. After the application
of a DC field for a few hours, a small reversible increment in the average soil stiffness was observed, with respect to the
untreated soil, while the hydraulic conductivity was not affected substantially. Dramatic changes of the mechanical and hydraulic
soil properties, correlated to changes of the soil pH, were observed following non-conditioned electrokinetic treatment with
duration of the order of days. 相似文献
16.
Data collection, both automatic and manual, lies at the heart of all empirical studies. The quality of data collected from
software informs decisions on maintenance, testing and wider issues such as the need for system re-engineering. While of the
two types stated, automatic data collection is preferable, there are numerous occasions when manual data collection is unavoidable.
Yet, very little evidence exists to assess the error-proneness of the latter. Herein, we investigate the extent to which manual
data collection for Java software compared with its automatic counterpart for the same data. We investigate three hypotheses
relating to the difference between automated and manual data collection. Five Java systems were used to support our investigation.
Results showed that, as expected, manual data collection was error-prone, but nowhere near the extent we had initially envisaged.
Key indicators of mistakes in manual data collection were found to be poor developer coding style, poor adherence to sound
OO coding principles, and the existence of relatively large classes in some systems. Some interesting results were found relating
to the collection of public class features and the types of error made during manual data collection. The study thus offers
an insight into some of the typical problems associated with collecting data manually; more significantly, it highlights the
problems that poorly written systems have on the quality of visually extracted data. 相似文献
17.
Ivan Cimrák 《Archives of Computational Methods in Engineering》2007,15(3):277-309
The Landau-Lifshitz (LL)equation of micromagnetism governs rich variety of the evolution of magnetization patterns in ferromagnetic
media. This is due to the complexity of physical quantities appearing in the LL equation. This complexity causes also an interesting
mathematical properties of the LL equation: nonlocal character for some quantities,nonconvex side-constraints, strongly nonlinear
terms. These effects influence also the numerical approximations. In this work, recent developments on the approximation of
weak solutions, together with the overview of well-known methods for strong solutions,are addressed.
Author is supported by the Fund for Scientific Research - Flanders FWO (Belgium). 相似文献
18.
1 Introduction Rear axle bevel gearis a vital kind of annular accessory with high precision and hugeload availablefeatures ,andit is widely used as the differential drive in automobiles and tractor .In China ,the traditional manufactureapproach of producing the rear axle bevel gear blankis die forging,which not only requires a highinvestment ofproduct equipments , but also involves a low material utilization and great noise .In order to overcome thesedrawbacks , manyresearchers have done a gre… 相似文献
19.
旋风燃烧器冷态模型内颗粒运动轨迹计算 总被引:2,自引:0,他引:2
在冷态模型流场内,考虑气流对粉煤颗粒的气动阻力,建立其运动微分方程式。通过计算,得到九种粒径的颗粒在流场中的运动轨迹、停留时间、着膜位置和气-固相相对速度与该燃烧器几何参数和气动参数的关系,为燃烧器的深入研究提出了建议。 相似文献
20.
Li Yu-cheng Teng Bin 《水动力学研究与进展(B辑)》1993,(2)
By using Cokelet's wave theory,the limiting wave height and the relative waveangular frequency in wave-current field were calculated in this paper.It is indicated by numeri-cal calculation that if the water depth is not too small,the result given by authors'calculationare very close to the results of limiting wave height by Dalrymple(1975)and to the data of rel-ative wave angular frequency by linear wave theory;but if water depth is rather small,thereare some discrepancy, 相似文献