A position optimization strategy of the dynamic vibration absorber for the noise control of the power equipment

Power equipment shows obvious low frequency line spectrum noise characteristics due to the power frequency. The effective noise control of the power equipment can be achieved by installing dynamic vibration absorbers (DVAs) on the structure surface of electrical equipment. However, if DVAs are not installed properly, considering the cases that they are installed at the vibration mode node position, the low radiation vibration mode and the redistribution of the integrate vibration power, the vibration and noise absorbing performances of DVAs may degrade. In order to achieve efficient vibration absorption and noise reduction on the power equipment, this paper proposes a low-frequency noise reduction technology for power equipment based on DVAs. The position optimization of the DAVs using in the power equipment is studied for the first time. Aimed at the single frequency radiated sound power of equipment, the integrate radiated sound power of the equipment is minimized through adjusting the position parameters of DVAs. A numerical case is studied to verify the effectiveness of the proposed DVAs position optimization. The results show that the noise control effect of the power equipment with the optimized DVAs is significantly improved. The method proposed in this paper solves the noise problem of the power equipment, which provides reference for power noise control

The Influence of Residual Coagulant Al on the Biofilm EPS and Membrane Fouling Potential in Wastewater Reclamation

Biofouling is inevitable in wastewater reclamation when using membrane technology. In particular, the extracellular polymeric substances (EPS) from biofilm is a major contributor to biofouling. Coagulation is critical in the process of reusing wastewater before membrane treatment, and residual coagulants (e.g., Al salts) are able to alter the characteristics of the biofilm EPS. However, the distribution of residual Al across varying biofilm EPS fractions and its effect on the membrane fouling potential resulting from biofilm EPS remains unclear. We found that 34% of the residual Al was present in the soluble EPS (S-EPS), 26% in the loosely bound EPS (LB-EPS) and 40% in the tightly bound EPS (TB-EPS). Moreover, compared with the control groups, the residual Al in biofilm induced more biofilm formation and more EPS formation. Al reduced the zeta potential and increased the hydrophobicity of the EPS. These changes induced a significant rise in the membrane fouling potential of S-EPS and LB-EPS. This work provides coagulation support for wastewater reclamation using membrane technology

High-Performance TiO₂ Nanotubes/Poly(aryl ether sulfone) Hybrid Self-Cleaning Anti-Fouling Ultrafiltration Membranes

A series of novel self-cleaning hybrid photocatalytic ultrafiltration (UF) membranes were fabricated to separate polyacrylamide, which is widely used as a commercial flocculant. To maximize the self-cleaning and anti-fouling properties of hybrid membranes, high surface area TiO2 nanotubes (TNTs) with excellent photocatalytic activity were homogeneously introduced into a poly(aryl ether sulfone) matrix by chemical bonds. The chemical structure, micromorphology, hydrophilicity, separation efficiency, fouling behavior, and self-cleaning property of the prepared hybrid membranes were well characterized and evaluated. For the optimal sample, the flux recovery ratio increased from ~40% to ~80% after simulated sunlight irradiation for 20 min, which was attributable to the homogeneous dispersion and efficient photocatalytic degradation ability of TNTs. Furthermore, the intelligent fabrication strategy enhanced the anti-aging ability of the hybrid membranes via the use of a fluorine-containing poly matrix. This work provided new insight into the fabrication of high-performance self-cleaning inorganic/organic hybrid membranes

Effects of Chitosan Oligosaccharide on Production Performance, Egg Quality and Ovarian Function in Laying Hens with Fatty Liver Syndrome

This study aimed to investigate the role of chitosan oligosaccharide (COS) as an additive in the feed of laying hens with fatty liver syndrome (FLS). Effects on production performance, egg quality as well as ovarian function were determined. A total of 360 Lohmann Pink-shell laying hens (28 weeks old) were randomly assigned to 5 groups (6 replicates × 12 birds). Hens were fed with a basal diet and a high-energy low-protein (HELP) diet supplemented with 0, 200, 400 and 800 mg/kg COS. COS reversed the lowered laying rates, increased feed-to-egg ratios and decreased albumen heights and Haugh units induced by the HELP diet. Additionally, COS improved the ovarian morphologies damaged by the HELP diet. Furthermore, COS enhanced antioxidant enzyme activities, reduced malonaldehyde levels and downregulated the mRNA expressions of nuclear factor kappa B, pro-inflammation cytokine genes and pro-apoptosis-related genes, while it upregulated the mRNA expression of anti-apoptosis-related genes in the ovaries of HELP-diet-fed hens. These findings suggested that dietary COS supplementation could improve production performance and egg quality in laying hens with FLS, and these beneficial effects were linked to improved ovarian morphology, which was attributed to decreased oxidative stress, inflammation and apoptosis in the ovaries