Experimental Study of Thin Wall Milling Chatter Stability Nonlinear Criterion

AbstractThe nonlinear dynamic behavior of milling process has been accompanied by the entire cutting process. In order to accurately determine and predict chatter stability of machining process, this article studied at both ends of the fixed thin part nonlinear criterion of milling chatter stability with experimental method. The experiment takes the vibration signal of thin part as the study object. And it analyses the vibration signal of different processing parameters based on the phase plane method, Poincare method and spectral analysis. Then, the relationship between the maximum Lyapunov exponent and the spindle speed and milling depth changes is discussed. Finally, taking the largest Lyapunov exponent as the criterion, the study determines the chatter stability domain of milling by using contour method. The comparative analysis is based on the milling chatter stability domain which obtained from the full discrete method. The experiments obtained the nonlinear stability criterion of aviation aluminium alloy 7075-T6 thin part

Shaping the future of application for information and communication technology in national economic analysis

Characterized by networking, digitization, and intellectualization, the new generation of Information and Communication Technologies (ICTs) has promoted integration of various national economic industries, with a more significant leading role in the socio-economic development. In order to describe the influence of ICT industries on economic growth, this paper has comprehensively analyzed the contribution mechanism of ICTs to current economy. Crucial indicators, such as Total Telecommunications Business (TTB), Data Traffic (DT), and Computing Power Development Index (CPDI), have been innovatively selected to sufficiently describe the data circulation scale and the processing capacity in the era of digital economy. Based on relevant statistics of 31 provinces (municipalities or autonomous regions) in China from 2011 to 2020, quantitative results have been put forward to interpret the impact of ICT industries on the national economy development by using correlation coefficient analysis and data regression analysis methods. The measurement results show that TTB, DT, and CPDI are positively correlated with the national economic development, indicating that each 1% increasement of TTB, DT, and CPDI increases Gross Domestic Product (GDP) by 0.08%, 0.09%, and 0.6%, respectively

The variation of morphological features and mineralogical components of biological soil crusts in the Gurbantunggut Desert of Northwestern China

Increasingly complex life forms were found in older biological soil crusts in the Gurbantaunggut Desert in Northwestern China. These crusts may play a critical role in mineral erosion and desert soil formation by modifying the weathering environment and ultimately affecting mineralogical variance. To test this hypothesis, variations in the morphological features and mineralogical components of successional biological soil crusts at 1 cm were studied by optical microscopy, SEM and grain size analysis. Concentrations of erosion-resistant minerals decreased with crust succession, while minerals susceptible to weathering increased with crust development. Neogenetic minerals were found in late stage crusts, but not in early stage crusts. Silt and clay concentrations were highest in early formation crusts and soil mean particle size decreased with crust succession. Cyanobacteria, lichen and moss were shown to erode and etch rocks, and secondary minerals produced by weathering were localized with the living organisms. Thus, more developed crusts appeared to contribute to greater mineral weathering and may be a major cause of mineralogical variance seen in the Gurbantunggut Desert. The greater activity and complexity of older crusts, as well as their improved moisture condition may function to accelerate mineral weathering. Therefore, protection and recovery of biological crusts is vital for desert soil formation

Mesenchymal Stem Cells Combined With Electroacupuncture Treatment Regulate the Subpopulation of Macrophages and Astrocytes to Facilitate Axonal Regeneration in Transected Spinal Cord

Objective Herein, we investigated whether mesenchymal stem cells (MSCs) transplantation combined with electroacupuncture (EA) treatment could decrease the proportion of proinflammatory microglia/macrophages and neurotoxic A1 reactive astrocytes and inhibit glial scar formation to enhance axonal regeneration after spinal cord injury (SCI). Methods Adult rats were divided into 5 groups after complete transection of the spinal cord at the T10 level: a control group, a nonacupoint EA (NA-EA) group, an EA group, an MSC group, and an MSCs+EA group. Immunofluorescence labeling, quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay, and Western blots were performed. Results The results showed that MSCs+EA treatment reduced the proportion of proinflammatory M1 subtype microglia/macrophages, but increased the differentiation of anti-inflammatory M2 phenotype cells, thereby suppressing the mRNA and protein expression of proinflammatory cytokines (tumor necrosis factor-α and IL-1β) and increasing the expression of an anti-inflammatory cytokine (interleukin [IL]-10) on days 7 and 14 after SCI. The changes in expression correlated with the attenuated neurotoxic A1 reactive astrocytes and glial scar, which in turn facilitated the axonal regeneration of the injured spinal cord. In vitro, the proinflammatory cytokines increased the level of proliferation of astrocytes and increased the expression levels of C3, glial fibrillary acidic protein, and chondroitin sulfate proteoglycan. These effects were blocked by administering inhibitors of ErbB1 and signal transducer and activator of transcription 3 (STAT3) (AG1478 and AG490) and IL-10. Conclusion These findings showed that MSCs+EA treatment synergistically regulated the microglia/macrophage subpopulation to reduce inflammation, the formation of neurotoxic A1 astrocytes, and glial scars. This was achieved by downregulating the ErbB1-STAT3 signal pathway, thereby providing a favorable microenvironment conducive to axonal regeneration after SCI

Facile synthesis of SrCO 3 nanostructures in methanol

Highly dispersive strontium carbonate (SrCO 3 ) nanostructures with uniform dumbbell, ellipsoid, and rod-like morphologies were synthesized in methanol solution without any additives. These SrCO 3 were characterized by X-ray diffraction, field emission scanning electron microscopy, and N 2 adsorption-desorption. The results showed that the reaction temperature and the methanol 3 particles. The dumbbell-like SrCO 3 exhibited a Broader-Emmett-Teller surface area of 14.9?m 2 ?g ?1 and an average pore size of about 32?nm with narrow pore size distribution. The formation mechanism of the SrCO 3 crystal was preliminary presented

Optimization of Ni/ZnZr Catalyst for Enhanced Syngas Yield in Catalytic Pyrolysis of Rice Straw

To enhance the catalytic performance of nickel-based catalysts and improve their efficiency in biomass pyrolysis, a nickel-based catalyst supported on a ZnZr composite carrier was synthesized using the sol-gel method. The morphological changes of the catalyst before and after the reaction were observed using X-ray diffraction, scanning electron microscopy, nitrogen gas adsorption, temperature-programmed reduction, and other methods to analyze its catalytic performance. A series of experiments were conducted to explore the optimal conditions for the catalyst's gas production, including carrier material ratios, loading amounts, residence time, and reaction temperature. The bimetallic carrier of Zn and Zr provided a higher specific surface area, allowing the metallic nickel to enter its mesopores. The synergistic effect of the bimetallic system facilitated the catalytic activity of nickel, significantly enhancing gas production. The maximum CO and H2 production were achieved at Zn/Zr = 6/4. The catalyst achieved an optimal gas yield of 507 mL/g at a residence time of 20 min and a reaction temperature of 800 °C, demonstrating strong stability

Improvement of extrudability and self-support of emulsion-filled starch gel for 3D printing : Increasing oil content

This work investigated the mechanism of increasing oil content in synchronously enhancing extrudability and self-support of β-carotene loaded starch-based emulsion-filled gels (S-EFG) during 3D printing in terms of gel properties. Increasing emulsion oil content enhanced the storage modulus, relaxation modulus, and hardness of gels, which indicated sodium caseinate-stabilized emulsions were active fillers in the starch gel. Thus, printed products with high oil content were less prone to collapse when selecting models with higher height. In addition, lower yield stress, relaxation time, and higher frequency dependence were observed in S-EFG with higher oil content (30–50 %) due to the lubricating/plasticizing effect of oils, which corresponded to the smoother extruded filament. Furthermore, the retention of β-carotene in high oil content gel was higher after heat treatment due to denser microstructure. These results indicated that the extrudability and self-supporting of S-EFG were simultaneously improved by increasing oil content under the active filling effect and lubricating/plasticizing effect of emulsions

Effect of induction mode on 3D printing characteristics of whey protein isolate emulsion gel

This study mainly explored the influence of different induction modes such as NaCl and Transglutaminase on the 3D printing characteristics of whey protein isolate emulsion gel. The properties of gel were characterized from rheological properties, microstructure, Fourier transform infrared spectroscopy, thermal stability and other aspects, and the relationship between 3D printing molding characteristics of gel and its applicability as a diet for dysphagia was discussed. Strain and frequency sweep showed that the addition of NaCl made gel difficult to be extruded during printing, while the addition of TG could get the opposite result. From a microscopic point of view, too high concentration of NaCl would lead to the disordered aggregation of proteins, which would reduce the structural strength of gel and make the water binding unstable. The addition of TG made the gel network have an orderly three-dimensional structure, making the water binding more stable. Both NaCl and TG can cause the secondary structure of protein to be more orderly and the thermal stability to be reduced, and the texture characteristics such as hardness, resilence, springiness, gumminess and chewiness to be reduced. During 3D printing of emulsion gel containing high concentration of NaCl, unsmooth extrusion filaments and pattern collapse occurred. TG can significantly improve the accuracy of 3D printing products. This study provided a basis for the application of whey protein isolate emulsion gel in 3D printing

Synthesis of superfine calcium carbonate during causticization in highly alkaline system for utilization of high-alumina fly ash

In the alumina extraction process of high-alumina fly ash, alkali was used to remove amorphous silica and then recovered through causticization. Focusing on the causticization process, the coupling control of CO32- conversion and CaCO3 crystallization is important to secondary-pollution reduction and high-value utilization. Influences of temperature, stirring rate, feeding time, Ca(OH)(2) concentration, and calcium/carbonate (Ca2+/CO32-) ratio on the conversion and CaCO3 morphology were investigated. Feeding time and Ca2+/CO32- ratio showed crucial effects on the conversion and crystallization of CaCO3 particles. Under optimized conditions, the conversion of CO32- can reach 95.67%, and the alkali can be well recycled with the generation of superfine calcium carbonate. Furthermore, the morphology evolution of CaCO3 was investigated in the reaction process. At the beginning of causticization, a combination of amorphous and crystalline structures can be observed. Subsequently, cubic and homogeneous morphologies were formed. At the end of the reaction, the edges of the cubic particles were dissolved, and the large particles with irregular shapes were formed by the joint of small ones in the alkaline system. (C) 2016 Elsevier B.V. All rights reserved.</p