An Improved Dynamic Modelling for Exploring Ball Bearing Vibrations from Time-Varying Oil Film

Bearings are key components in rotating machinery,which is widely used in many fields,such as CNC machines,wind turbines and induction machines.The increasingly harsh operation environment can lead to wear and tear on raceways and reduce the precision and reliability of bearing or even machinery.Lubrication could relieve the wear to some degree,which is benefit to prolong the bearing’s life.Thus,investigation on the vibration responses under the influence of oil film is of great significance.However,for mechanism analysis,how to include the oil film into the bearing dynamic model affects the result and efficiency of solution.To address this problem,this study proposed a fast algorithm through load distribution and interpolation when calculating oil film stiffness and thickness during the solution of bearing vibration model.Analysis of oil film on vibration is carried out and a bearing test rig is designed to verify the proposed model.Numerical simulation result shows that rotational speed and load have vital effect on oil film and vibration.The experimental result is consistent with the simulation,which shows that the proposed model has a better performance on modeling bearing vibration and the method of considering oil film is reasonable.

Systematic assessment of dredged sludge dewaterability improvement with different organic polymers based on analytic hierarchy process

Organic polymeric flocculants are commonly used in improving dredged sludge dewaterability, but less attention has been paid to residual water quality. In this paper, the effects of cationic etherified starch(CS) and poly-dimethyl diallyl ammonium chloride(PDDA) on dredged sludge dewatering efficiency and residual water quality of Baiyangdian lake were comprehensively investigated and evaluated by analytic hierarchy process(AHP). The results indicated that PDDA had stronger electrical effect and flocculation performance compared with CS, resulting in more efficient dewatering performance. PDDA can reduce the pollutants of discharged residual water, while CS significantly promoted the increase of NH_(4)^(+)-N and NO_(3)^(–)-N in the residual water. The increase of NH_(4)^(+)-N in the residual water of CS was due to the release of dredged sludge, while the increase of NO_(3)^(-)-N was introduced by CS leaching. AHP showed that PDDA performed better in flocculation treatment of dredged sludge than other organic polymers. This work provides a method for optimization of flocculation treatment for dredged sludge dewaterability.

Synthesis of highly effective absorbents with waste quenching blast furnace slag to remove Methyl Orange from aqueous solution

Water quenching blast furnace slag （WQBFS） is widely produced in the blast furnace iron making process. It is mainly composed of CoO, MgO, A1203, and SiO2 with low contents of other metal elements such as Fe, Mn, Ti, K and No. In this study, WQBFS was treated with grinding, hydrochloric acid acidification, filtration, filtrate extraction by alkali liquor and a hydration reaction. Then BFS micropowder （BFSMP）, BFS acidified solid （BFSAS） and BFS acid-alkali precipitate （BFSAP） were obtained, which were characterized by X-ray diffrac- tion, scanning electron microscopy, X-ray fluorescence and Brunauer-Emmet-Teller （BET） specific surface area. The decoloration efficiency for Methyl Orange （MO） was used to evaluate the adsorptive ability of the three absorbents. The effects of adsorptive reaction conditions （pH and temperature of solution, reaction time, sorbent dosage and initial concentration） on MO removal were also investigated in detail. The results indicated that BFSAP performed better in MO removal than the other two absorbents. When the pH value of MO solutions was in the range 3.0-13.0, the degradation efficiency of a solution with initial MO concentration of 25 mg/L reached 99.97% for a reaction time of 25 rain at 25℃. The maximum adsorption capacity of BFSAP for MO was 167 mg/g. Based on optimized experiments, the results conformed with the Langrnuir adsorption isotherm and pseudo-second-order kinetics. Among inorganic anions, SO2- and PO4- had significant inhibitory effects on MO removal in BFSAP treatment due to ion-exchange adsorption.

A Bioinspired Adhesive Sucker with Both Suction and Adhesion Mechanisms for Three-Dimensional Surfaces

There are significant advantages to investigate underwater attachments,which would be valuable in providing inspirations and design strategies for multi-functional surfaces and underwater robots.Here,an abalone-inspired sucker integrating an elastic body and a membrane structure is proposed and fabricated filled with rigid quartz particles to adjust the backing stiffness of the contact like abalone.The membrane is used to conform and contact surfaces well,the center area of which can be pulled in exposed to a negative pressure differential,to create a suction cavity.The pulling experiments indicate that the sucker can adhere to three-dimensional surfaces with both suction and adhesion mechanisms in both dry and liquid environments.The switching between soft/hard contact states leads to the change of adhesive strength over 30 times.Furthermore,we provide theoretical analysis on how the sucker work well in both dry and liquid environments.Finally,the developed sucker can easily lift up smooth planar objects and 3D objects,and can grip objects both smaller and larger than the size of the sucker,which have a difficulty for conventional suckers or friction-based grippers.The potential application of the sucker in flexible transfer robot is demonstrated on various surfaces and environments,paving the way for further bio-inspired adhesive designs for both dry and wet scenarios.