No abstract

Tri-n-butyl phosphate (TBP) is used as the extraction agent for the extraction of o-aminophenol (OAP) in active solvents and inactive solvents. The effects of aqueous solution pH, solvents, concentration of TBP, and the initial OAP concentration on distribution coefficient (D) are investigated. Results show that the neutral OAP molecule is hydrogen-bonded to TBP effectively into the organic phase, and D was maximum when the equilibrium pH was between pK a1 and pK a2. The extraction efficiency is TBP–1-octanol > TBP–kerosene > TBP–carbon tetrachloride > TBP–chloroform, when the concentration of TBP is between (0.3632 and 0.7264) mol·L–1, while the result is TBP–kerosene > TBP–1-octanol > TBP–carbon-tetrachloride > TBP–chloroform when the concentration increases [(1.0896 to 1.8159) mol·dm–3]. Fourier transform infrared spectroscopic analysis shows that the extractive behavior is controlled by hydrogen bonding. An expression for equilibrium D is proposed, and the parameters of the apparent extraction equilibrium constants (K) and the complex ratio (n) (TBP vs OAP) were calculated by fitting the experimental data. It was found that the K and n are 5.97, 5.37, 5.47, and 2.99 and 1.56, 1.51, 1.47, and 1.76 in TBP/kerosene, 1-octanol, carbon tetrachloride, and chloroform, respectively.

Deep learning provides a feasible fault diagnosis method for intelligent mechanical systems. However, this method requires a large amount of marking data, which greatly limits its application in the actual industry. Therefore, this paper proposes a multi-layer adaptive convolutional neural network unsupervised domain adaptive bearing fault diagnosis method (MACNN), which is especially suitable for bearing fault classification under variable working conditions. First, a new method to improve domain alignment is proposed (LD-CORAL). This method uses Log-Euclidean distance to measure deep coral loss, which solves the problem that the covariance matrix cannot be aligned correctly in the manifold structure. Then, it proposes multi-layer adaptation of LD-CORAL loss in the fully connected layer, and combines Center-Based discriminative loss to improve the feature learning ability of the model, which can improve the classification accuracy and domain adaptation performance of the model. Finally, in order to verify the effectiveness and feasibility of the proposed method, the method is applied to the multi-fault diagnosis of gearbox bearings under variable working conditions. Comparing the classification results of different methods, the conclusion shows that this method is more effective for bearing fault classification under variable working conditions.

The biodegradable composite films were prepared from corn stalk microcrystalline cellulose as filler and chitosan as polymeric matrix. The crystallinity, the tensile properties and the thermal properties of the composites were tested. The results show that the tensile properties and thermal properties were improved with the addition of corn stalk microcrystalline cellulose. When corn stalk microcrystalline cellulose account for 10% of the chitosan quality, the initial decomposition and maximum weight loss rate temperature was raised by 13.19°C and 38.84°C, tensile strength increased by 83.55% and elongation at break increased by 77.38% compared to those of pure chitosan

A direct coagulation casting method for silicon carbide ceramic suspension using dispersant crosslink reaction is reported. Polymer electrolyte (polyethyleneimine, PEI) was used as dispersant to prepare silicon carbide suspension. Common food additives (carboxymethyl cellulose, CMC) were used to coagulate the electrosteric stabilized silicon carbide suspension. There was a well disperse silicon carbide suspension with 0.2 wt% PEI at pH = 5-6. Influence of coagulant on viscosity and zeta potential of the silicon carbide suspension was investigated. It indicates that the high solid loading silicon carbide suspension can be destabilized and coagulated at elevated temperature. It can be attribute to the gradual decrease of electrosteric force due to the crosslink reaction between PEI and CMC. Silicon carbide wet green body with compressive strength of 1.99 MPa could be demolded at 70°C which is higher than that prepared by traditional DCC and dispersant reaction method for nonoxide ceramics. Dense silicon carbide ceramics with relative density above 98.8% and 99.3% had been prepared by liquid phase pressureless and hot pressed sintering, respectively.