Influence of Membrane Vibration on Particles Rejection Using a Slotted Pore Membrane Microfiltration

A new method is proposed to increase the rejection in microfiltration by applying membrane oscillation, using a new type of microfiltration membrane with slotted pores. The oscillations applied to the membrane surface result in reduced membrane fouling and increased separation efficiency. An exact mathematical solution of the flow in the surrounding solution outside the oscillating membrane is developed. The oscillation results in the appearance of a lift velocity, which moves oil particles away from the membrane. The latter results in both reduced membrane fouling and increased oil droplet rejection. This developed model was supported by the experimental results for oil water separation in the produced water treatment. It was proven that the oil droplet concentration was reduced notably in the permeate, due to the membrane oscillation, and that the applied shear rate caused by the membrane oscillation also reduced pore blockage. A four-times lower oil concentration was recorded in the permeate when the membrane vibration frequency was 25 Hz, compared to without membrane vibration. Newly generated microfiltration membranes with slotted pores were used in the experiments.

Numerical Study of Vibration Characteristics for Sensor Membrane in Transformer Oil

Membrane is the most important element of extrinsic Fabry-Perot interferometer sensors. Studying the relationship between working medium viscosity and membrane vibration characteristics are critical to the sensor design because the transformer oil viscosity will cause viscous loss during membrane vibration. The numerical investigation of membrane vibration characteristics in transformer oil is performed based on the finite element method. Besides, the effect of energy loss caused by viscosity is examined. It is firstly showed that the membrane has the highest sensitivity for the first-order vibration mode, and the transformer oil reduces the fundamental frequency by 60%. Subsequently, when viscosity and heat loss are considered, the amplitude is less than one-fifth of that without energy loss. The viscosity has a more significant effect on the velocity and temperature fields when the vibration frequency is close to the natural frequency. Finally, viscosity has a remarkable impact on the time domain response. Mechanical energy is converted into thermal energy during the vibration and the amplitude will gradually decrease with time. The effect of energy loss caused by viscosity on the membrane vibration characteristics is revealed, which would be important for an oil-immersed membrane design.

Size and crystal symmetry breaking effects on negative thermal expansion in ScF3 nanostructures

New membrane vibration and surface symmetry breaking effects determine the negative coefficient of thermal expansion at the nanoscale.

Research on The Design of Children’s Toys and Teaching AIDS Based on Sound Science

Playing teaching aids is an indispensable auxiliary tool for children’s growth and development, and hearing is an important way for children to perceive and understand the world. According to children’s learning and cognitive laws, and in combination with the design concept, educational function and application orientation of play AIDS, a series of play aids products, such as “audio tumbler”, “microphone” and “simulated tympanic membrane vibration”, are designed to deeply reflect how the sound is generated, bringing a new knowledge system for children, making learning more interesting and interactive It can help to fully cultivate children’s interest, promote children’s development and improve their interest in learning.

Analysis on a vibration character of hollow fiber membrane bundle in MBR

We have focused on membrane vibration in MBR to find an effective design for the reduction of membrane fouling. In the previous study, we developed a direct measurement method for membrane vibration of a hollow fiber membrane (HFM) using an accelerometer (ACM). In this study, we studied on vibration characters on an HFM bundle in a practical membrane module in MBR using the ACMs in a large transparent water tank. Three ACMs were attached at the middle (P1), top (P2) and bottom (P3) position along a center line in the HFM bundle in which air was supplied from a diffuser below the membrane module with different aeration rates from 0 to 250 L/min. The acceleration of membrane vibration time series for the X-axis direction (left-right displacement) and Z-axis direction (back-front displacement) was recorded at three positions. The average vibration amplitudes of the acceleration along both directions at each position were increased as the aeration rate was increased. The HFM bundle showed a collective vibration with a frequency peak between 0 and 50 Hz. The Z-axis motion character of HFM bundle is regarded as a sheet vibration. The obtained vibration character was useful for the new design of a membrane module in MBR against the membrane fouling.