ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677594

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper investigates a two‐dimensional flow past a circular cylinder placed within a channel. The study is focused on the emergence of a periodic flow pattern subjected to steady boundary conditions. Effects of domain truncation and the cylinder size on flow developments are also examined. The results indicate that the unsteady flow appears to be periodic and there is only one period. The period approaches the one in an infinite flow domain as the cylinder size is decreased.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677595

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

A general camera model in a lateral‐stereo setup is developed. In such a model, the image planes do not have to be parallel, the longitudinal planes on which the cameras are placed need not be identical, and the camera parameters are not required to be the same. The developed general model is employed to determine the position and orientation of a box, and the errors resulting from inaccuracy in camera parameters and image preprocessing are very small compared to the traditional parallel model.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677596

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The existence of the secondary current changes the vertical and lateral velocity distributions, bed topography, and sediment gradations in an alluvial channel bend. An analytical solution is proposed to describe the transverse bed slope, lateral depth‐averaged mean velocity distributions and sediment distributions for both developing and fully‐developed reaches of an alluvial channel bend under steady uniform flow conditions. The theory is based on the findings of Odgaard [20] and Hussein and Smith [10], coupled with a streamwise momentum equation, and a longitudinal force balance equation. The results are verified by experimental data of Lee [15] and Odgaard and Bergs [21], and by field data of Sacramento River [22]. The solutions obtained are quite accurate.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677597

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The surface roughness of workpiece is improved during spark‐out. This improvement is due to the overlapping cutting between abrasive and workpiece. The reduction of the surface roughness during spark‐out is promoted by grain sharpness as a result of fracture wear. If the value and the reduction trend of the surface roughness during spark‐out can be predicted, the automation and the promotion of efficiency of grinding can be achieved. Therefore the prediction of surface roughness is important. In this study, the prediction of spark‐out surface roughness was performed by the computational simulation. The effect of table speed, depth of cut and grain shape on the surface roughness during spark‐out could be analyzed by the computer simulation instead of the experiment. The effect of the enlarged overlapping area can be simulated by changing the angle of grain tip. The angle of grain tip can be adjusted by changing dressing lead and sharpness of dressing tool in reality.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677598

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The objective of this paper is to derive a systematic algorithm to decide the optimal location and size of shunt capacitors and filters for distribution systems with harmonic distortion. In this paper, the problem of reactive power compensation is first formulated as a nonlinear programming of minimization of real power loss and capacitor cost under voltage constraint to decide the optimal locations and sizes of shunt capacitors. The harmonic load flow is then applied to solve the total voltage harmonic distortion factor (HDF). Finally, the tuning frequency of the single‐tuned filter and the capacity and voltage ratings of the corresponding reactor and capacitor are determined so that both the harmonic distortion and the reactive power compensation can be solved simultaneously. To demonstrate the performance and effectiveness of the proposed methodology, a practical distribution feeder with nine large industrial customers is selected for computer simulation. It is concluded that proper design of harmonic filters should be undertaken to solve the harmonic resonance problem, as well as the reactive power compensation for distribution systems with nonlinear loads.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677599

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper investigates the effectiveness of a passive Tuned Mass Damper (TMD) in reducing the primary structural responses under stochastic environmental loadings. Extensive parametric studies are performed to examine the influence of the variation of fundamental frequency and frequency bandwidth of the input excitation on the structural responses with and without installation of TMD. It is concluded that the passive TMD is a useful vibration control device and is more appropriate to a structure which fundamental frequency is less than that of input excitation. Design charts and equations to determine the optimum values of mass, damping, and stiffness for a passive TMD are illustrated. This optimum TMD can reduce both earthquake‐ and wind‐induced structural responses and is thus recommended for all design purposes. In addition, this paper shows passive TMDs are more effective to diminish the vibrations induced by wind than earthquake.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677600

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper deals with the dynamic stiffness of rigid strip footings resting on irregular soil stratum. Above the fundamental frequency of soil stratum, the change in the inclination of the rigid bed‐rock causes the variations of dynamic stiffness with frequency to shift, leading to significant differences at certain ranges of frequencies for shallow stratum; however, such differences become less for deeper soil stratum. On the other hand, if only the soil layers are inclined, no significant shift in the variations of dynamic stiffnesses with frequency is observed over the range of frequencies considered. The increase in the angle of inclination of soil layers leads to a reduction in the real stiffnesses of all modes of motion and the damping of vertical stiffness, while the opposite trend is observed for the damping of swaying and rocking stiffnesses.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677601

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

VOC(Volatile organic compound) emission rate was modelled in this study. The effects of the different environmental factors and the additives upon the emission rates were also determined. The study was conducted in a test chamber and in the field for determination of the emission rate of methyl ethyl ketone (MEK). Additionally, the theory of mass transfer was used to derive an MEK emission model with three variables (temperature, humidity, ventilation rate) and five coefficients (T1,R1,KB,ACHstdandCstd); these were determined by the results of emission rate in a test chamber. The emission rate of MEK ranged from 16.1 × 103to 101.0 × 103mg/m2/hr/(g‐MEK) for those cases which used solvents and plasticizer, and from 5.6×103to 58.1×103mg/m2/hr/(g‐MEK) when PVC powder was added. Additionally, the MEK emission rates increased with an increase in temperature, humidity, and ventilation rate. The mass transfer coefficients of MEK determined from the VOC emission model were approximately 0.00246 m/sec for those cases which used solvents and plasticizer, and decreased by a factor of 0.67 to 0.00164 m/sec for those cases which used solvents, plasticizer and PVC powder.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677602

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

The dynamics and stability of a freely spinning body carrying a viscous ring nutation damper is analyzed. A local nonlinear analysis around the equilibrium point is used here to determine the stability criterion, since a linear stability analysis fails due to the appearance of a zero eigenvalue. The center manifold theorem is employed to reduce the dimension of the system. The averaging method is used to obtain equations expanded up to third order in a small parameter. A stability criterion and an explicit equation for the decay time constant of the wobble motion of the spinning body are found. The analytical solution is verified by comparing analytical results with numerical solutions of the original nonlinear equations of motion. The stability criterion shows that the motion is stable if the spin axis is the principal axis of the maximum moment of inertia. The effect of the damper parameters on the stability of the motion is secondary.

ISSN:0253-3839    

DOI:10.1080/02533839.1994.9677603

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor