Effect Of Vertical Vibration Research Articles

The onset of bioconvection in a suspension of negatively geotactic microorganisms with high-frequency vertical vibration

The effect of vertical vibration on the stability of a dilute suspension of negatively geotactic microorganisms in a fluid layer of finite depth is investigated. For the case of high-frequency vibration, solutions of governing equations are decomposed into two components: one which varies slowly with time and a second which varies rapidly with time. An averaging method is utilized to derive the equations describing the mean flow. Linear stability analysis is used to investigate stability of the obtained averaged equations.

Effects of vertical vibration on hopper flows of granular material

The discharge of granular material from a hopper subject to vertical sinusoidal oscillations was investigated using experiments and discrete element computer simulations. With the hopper exit closed, side-wall convection cells are observed, oriented such that particles move up along the inclined walls of the hopper and down at the center line. The convection cells are a result of the granular bed dilation during free fall and the subsequent interaction with the hopper walls. The mass discharge rate for a vibrating hopper scaled by the discharge rate without vibration reaches a maximum value at a dimensionless velocity amplitude just greater than 1. Further increases in the velocity decrease the discharge rate. This decrease occurs due to a decrease in the bulk density of the discharging material when vibration is applied.

Fluidization behavior of glass beads under different vibration modules

The expansion of free bubbling gas fluidized beds has been investigated experimentally in a two-dimensional perspex-walled bed. Glass beads were fluidized with dried air at varying gas velocities, while the bed was vibrated at different frequencies, amplitudes and directions to study their effects on the fluidization quality. The experimental results showed that the particle flow pattern depends on the vibration direction, especially at superficial gas velocities less than the minimum fluidization velocity U mf. The effect of horizontal vibration on fluidization behavior of glass beads exists at superficial gas velocities less than U mf, while the effect of vertical vibration on fluidization behavior still exists even at higher superficial gas velocities than U mf.

Leakers as a Function of Closure Type in Gallon-Size Plastic Bottles in Simulated Small Parcel Test Environment

Abstract This study investigated the effects of vertical vibration and drops on gallon-size plastic bottles in simulated small parcel shipping tests. Three types of round and F-style bottles were tested with different finish sizes. Three different types of closures were used on each type of bottle. Six bottles of each type were filled with water and capped with each closure type and packaged in single-wall RSC corrugated boxes with partitions. The packages were subjected to drop and vibration tests after being conditioned for 72 h at normal conditions of 23°C (73.4°F) and 50% relative humidity (RH), and accelerated conditions of 40°C (104°F) and 90% RH. The bottles were checked for application torques before testing and removal torques after testing. The results show the performance of the different types of closures and finish sizes. The larger size finish (63–400) F-style bottle showed the most leaks whereas the smaller finish (33–400) round-style bottles showed the fewest leaks. The bottles that were subjected to higher temperature conditioning showed more leaks and a greater reduction in removal torques.

Effects of vertical vibration on passenger activities: writing and drinking : C. Corbridge and M. J. Griffin 1991 Ergonomics34(10), 1313–1332. (20 pages, 13 figures, 3 tables, 12 references) (in English)

Effects of vertical vibration on passenger activities: writing and drinking : C. Corbridge and M. J. Griffin 1991 Ergonomics34(10), 1313–1332. (20 pages, 13 figures, 3 tables, 12 references) (in English)

Effects of vertical vibration on passenger activities: writing and drinking

Two laboratory studies have investigated how handwriting ability and holding a cup of liquid depend on the characteristics of whole-body vertical vibration. The effects of vibration magnitude (0.16 to 2.5 ms-2 r.m.s.), vibration frequency (0.5 to 10 Hz), and vibration duration (2 cycles to 10 s) on handwriting were studied with 20 subjects. Subjects were asked to copy letters of the alphabet by writing on a hand-held surface. Writing speed decreased and subjective ratings of writing difficulty increased with increasing vibration magnitude, particularly in the frequency range 4 to 8 Hz. Writing difficulty also increased with increasing duration of vibration. A 10 s exposure to 5 Hz vibration at 2.0 ms-2 r.m.s. resulted in subjective estimates corresponding to 'extremely difficult'. The effects of vibration magnitude (0.63 to 1.6 ms-2 r.m.s.), vibration frequency (0.5 to 10 Hz), and vibration duration (2 cycles to 10 s) on the spilling of liquid from a hand-held cup were also investigated in a group of 20 subjects. The probability of spilling the liquid, the quantity of liquid spilt, and subject's estimates of the probability of spillage were determined for all conditions. Greatest interference with the task occurred at 4 Hz, with the lowest vibration magnitude (0.63 ms-2 r.m.s.) causing measured and estimated spillage probabilities of approximately 85%. The interference was much less at other frequencies, with 0.63 ms-2 r.m.s. causing less than 10% measured probability of spillage below 3 Hz and above 5 Hz. The estimated probability of spillage was generally greater than the observed probability of spillage when the spillage probability was low, but less than the observed probability when the spillage probability was high. Increasing the duration of vibration increased the probability of spillage, and also increased the volume of liquid spilt.

THE RESEARCH ON THE LIMITED SPEED OF THE 4×4 OFF-ROAD VEHICLE ON UNEVEN ROAD

SUMMARY This paper, considering from the point of view of the effects of vertical vibration on the vehicle mobility,discusses the conditions of limited speed when 4×4 off-road vehicle traveling on uneven road. The criterion to evaluate the limited speed of off-road vehicles is developed. Five degree of freedom model of vertical vibration of the vehicle is established. The vibration responses of vehicle system are analysed in both time and frequency domains by means of computer simulation. The relationship between thecriterions and speed are established. The comparison of the road test results and the computer simulation results shows that there is a close agreement between them.This paper also discusses the influence of vehicle parameters on the limited speed for different road input and searches the approches to increase the limited speed. Also it provides a way to predict the limited speed and to optimige structure parameters of 4×4 off-road vehicle.

Experimental study of the effect of vertical vibrations on convection in a horizontal cylindrical layer

An experimental study is made of the effect of vertical vibrations on convection in a cylindrical layer formed by two horizontal coaxial cylinders of circular cross section at different temperatures.

The effect of vertical vibrations on the onset of convection in a planar rotating layer

The effect of vertical vibrations on the convection in a rotating planar fluid layer heated from below was studied. In this case a modulation parameter, the acceleration due to gravity, appears in the problem. The modulation of the parameter may have a significant effect on the onset of convective instability. Parameter modulation in nonrotating layers has been investigated in earlier work [1–3]. The presence of rotation significantly increases the complexity of the mathematical problem, introducing an additional dependence of the solution on the Taylor number Ta and the Prandtl number Pr. Furthermore, an oscillatory convection regime can occur at the stability limit in rotating fluids with Pr < 1. Parameter modulation in the rotating fluid may not only lead to a change in the stability limit and critical wavelength but also to a change in the eigenfrequency of the oscillatory convection. Rauscher and Kelly [4] examined the effect of parameter modulation on the convective stability of a rotating fluid only for the particular case of a sinusoidal variation in the temperature gradient with a small amplitude for Pr = 1, i.e., the effect of modulation was studied on only a steady convection regime.

The effect of vertical vibrations on natural convection heat transfer from a horizontal cylinder

Experiments were carried out to determine the increase in heat transfer rates as a result of mechanical vertical vibrations applied to horizontal cylinders. Two cylinders, one of 0.85cm and other of 1.27cm external diameter heated from inside by electrical resistance heaters were vibrated in still air. The ranges of amplitude, a, frequency, f, and the surface-air temperature difference, ΔT, for the first cylinder were 0–1.715 cm, 0–63.7 c/s and 18–150°C respectively. The corresponding values for the second cylinder were 0–1.78 cm, 0–68 c/s and 22–90°C. It was observed that for amplitude to diameter ratios exceeding 0.5, the relative vibrational heat-transfer coefficient increased almost linearly with the former irrespective of the frequency of vibration. Simple correlations based on experimental observations have been given to predict the vibrational heat-transfer coefficient from the known values of ΔT, a and f.

Response of Railroad Ballast to Vertical Vibration

The effect of vertical vibration on some railroad ballasts in laboratory tests is presented. The ballasts were found to behave in a similar manner to that previously reported for sands, i.e., peak acceleration was the main parameter affecting densification. For unsurcharged ballast, little increase in density occurred at peak accelerations below 1 g, a large increase in density occurred at peak accelerations between 1 g and 2 g, but little further increase in density occurred at higher peak accelerations. Surcharge pressures above 50 psi (345 kN/m²) led to an increase in the peak acceleration needed to produce a substantial increase in density. Gradings modeled on the Talbot grading equation with n values between 0.7 and 1.0 gave the highest densities under vibration. There was some downward migration of fine particles during vibration. The amount of segregation appeared to be independent of grading but dependent on the particular ballast tested.

Effect of vibration on the performance of off-road vehicles

Abstract : This paper first describes an experimental study on the effect of vertical vibration on shearing characteristics between vehicle running gear and terrain under simulated operating conditions. It is found that the amplitude of dynamic load and slip velocity have a profound effect on the horizontal shearing force developed on vehicular ground contact areas. In general, the higher the amplitude of dynamic load and the lower the slip velocity, the less the horizontal shearing force will be developed. The second part of the paper is devoted to the examination of the relationship between vehicle vibration and surface irregularity. By integrating the results of the study on vehicle vibration excited by surface roughness with the experimental results concerning the effect of vibration on vehicle-terrain interaction, a general framework correlating vehicle vibration and vehicle performance with terrain conditions is established. (Author)

低融点金属の過冷に関する研究

The effects of purity, overheating, cooling, the formation of oxide films, the addition of nonmetallic powder and vibrations, on the undercooling of Sn and Bi in a vertical shaped glass container were studied. A great defference between the undercooling behaviours of metals of 99.9% and >99.999% was found. Undercooling of 99.9%Sn and Bi increased in steps as the degree of overheating increased. It was also found that the effect of vertical vibrations on the undercooling was much greater than that of horizontal vibrations. The effect of vibrations was greatly increased by the addition of nonmetallic powder.

Effect of vertical vibration on respiratory airflow and transpulmonary pressure.

The response of the human thoracoabdominal system to whole-body, vertical, sinusoidal vibration has been studied. Peak acceleration of the shake table was held constant (±0.5 G), and frequency varied between 2 and 10 cycles/sec. Subjects were seated with trunk axes parallel with the direction of acceleration. The amplitude of forced airflow oscillation increased with frequency to an average 1,368 cm3/sec at 6 cycles/sec and then decreased. The maximum average volume of air forced in or out of the lung with vibration was 46 cm3 at 5 cycles/sec. Transpulmonary pressure fluctuation exhibited a peak average amplitude of 5.44 cm H2O at 5 cycles/sec. The response to square-wave table motion was also investigated. The transient flow oscillation produced by the step function had an average frequency of 5.6 cycles/sec. Measurements of the logarithmic decrement of transient flow oscillation indicate the total thoracoabdominal system is underdamped (hV = 0.1–0.2). The calculated damping for the lung subsystem indicates very high damping (hL = 4.5). Measurements of abdominal deformation produced by the step function suggest the transient flow oscillations result from close coupling of the lung to other components of the thoracoabdominal system. Note: (With the Technical Assistance of Tom Sharp, Roger Shannon, and Judith White) whole-body vibration; periodic vertical acceleration; vibration-induced changes in respiration; oscillation; mechanics of thoracoabdominal system Submitted on February 14, 1964