Advanced Materials Research Vols. 718-720

Abstract: With high-speed welding inverter and precisely controlling the welding current with arc-bridge state, advanced pulse current waveforms can be produced to optimize the transfer characteristics of short circuiting transfer welding. In this paper, the images of droplet/wire, and the transient data of welding current and arc voltage were simultaneously recorded to study the influence of peak arcing current, background arcing current and tail-out time on the stability of short circuiting transfer process. It was found that maximum short circuiting transfer stability is reached under specific welding conditions. Any deviation from these conditions will cause abnormal rises in arc voltage indicating instantaneous arc extinguishing and greater spatter. Optimal welding conditions were obtained to achieve the maximum stability of short circuiting metal transfer process.

Abstract: Room temperature ionic liquids (RTIL) have been developed to a central point of interest in both academia and industry. RTIL is non-volatile, thermally stable and non-flammable solvent. These properties can offer a green opportunity for sonochemical reactions. In this work, the cavitation bubble temperatures have been measured using methyl radical recombination (MRR) method. The temperatures measured in ImPF₆ are in the range of 3000 4000 K. Additionally, based on the bubble dynamic equation with the consideration of liquid surface tension, viscosity and radiative resistance, numerical simulations have been carried out to investigate the cavitation bubble dynamics. The difference of the temperatures obtained from the experiment and numerical simulations has been interpreted.

Abstract: In accordance to ASTM test standards, this paper presents experimental studies on quasi-static indentation tests on sandwich panels with carbon fiber reinforced facesheet and foam core. The indentation force vs. displacement curves were obtained. A series of tests with different indentation depth were carried out to study the damage modes and damage propagation process of foam core sandwich panels under quasistatic indentation force.

Abstract: This research developed and optimized the methods for simultaneous determination of tetracycline (TCs), macrolide (MLs) and sulfonamide (SAs) antibiotics in soils using accelerated solvent extraction (ASE)- solid-phase extraction (SPE)-high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Methanol-citric acid (pH=4.7) was used as extraction solvent, diatomite (washed by EDTA) was used as dispersing agent. Firstly, soil was extracted by ASE with the parameter conditions: pressure 1500 psi, temperature 70°C, static 10 min, 1 circle, then pre-concentration by SPE and followed by HPLC-MS/MS analysis. Recovery was 86.3%~97.4% for SAs, 67.3%~87.4% for TCs and 68.4%~78.3% for MLs. RSD < 9 % and r > 0.99. Limits of detection (LOD) was 0.5~0.9 ug/kg for SAs, 0.2~1.1 ug/kg for TCs and 0.2~0.3 ug/kg for MLs. This method determined 9 kinds of antibiotics within 15 min, the determination accuracy can meet the requirements of actual analysis.

Abstract: Bi₂O₃ Chaplet-like Nanoparticles have been fabricated. Most of them have the average inner diameter of 200nm and the mean rim thickness of 20nm. Photoluminescence spectra of the nanorings at room temperature were investigated, which demonstrated that the rings present excellent optical properties. The influence of aging time on the morphology and structure of β-Bi₂O₃ superstructures was also studied, indicating that the nanorings superstructures were transformed into nanoplates after a long aging time. The formation mechanism of the β-Bi₂O₃ superstructures was also explored. This approach will be further extended to solvent-controlled fabrication of related minerals with novel complex superstructures.

Abstract: Cooking method of wheat straw pulp was investigated by microwave radiation at ambient pressure. In the microwave irradiation, wheat straw was cooked with mixed-alkali at normal pressure. The optimum process conditions determined by single-factor and orthogonal experiments were provided as follows: total alkali content was 16%, the ratio of solid to liquid was 1:6,and microwave irradiation time was 45min. Paper performance tests was run and showed that the index was equal or better than those produced by conventional methods. A consistent yield (around 60.1%) of wheat straw pulp was observed after repeated experiments.

Abstract: Based on the viscosity of 10mPa.s after high speed shearing and the limit surfactants up to ultra-low interfacial tension, polymers and surfactant systems suitable for Longhupao oilfield were optimized by means of mixing formation simulation water with different polymers and surfactants. The relationship between the interfacial tension of the compound system and the component concentration, the effect of surfactants on viscosity, the injectivity of the compound system, etc. were studied on the basis of the research on the binary compound system. The results indicate that the viscosity of the compound system is lower than that of a single polymer solution to a certain degree and the compound system has good migration character in cores. In addition, core flooding experiments on slug combination optimization were made. The experiment results show that the compounded system with pre-pad polymers and surfactants has good oil displacement efficiency and in terms of enhancing the recovery efficiency, chemical flooding should be implemented as soon as possible.

Abstract: Cutting force is a key factor influencing the machining deformation of weak rigidity work pieces. In order to reduce the machining deformation and improve the process precision and the surface quality, it is necessary to study the factors influencing the cutting force and build the regression model of cutting forces. This paper discusses the development of the first and second order models for predicting the cutting force produced in end-milling operation of modified manganese steel. The first and second order cutting force equations are developed using the response surface methodology (RSM) to study the effect of four input cutting parameters (cutting speed, feed rate, radial depth and axial depth of cut) on cutting force. The separate effect of individual input factors and the interaction between these factors are also investigated in this study. The received second order equation shows, based on the variance analysis, that the most influential input parameter was the feed rate followed by axial depth, and radial depth of cut. It was found that the interaction of feed with axial depth was extremely strong. In addition, the interactions of feed with radial depth; and feed rate with radial depth of cut were observed to be quite significant. The predictive models in this study are believed to produce values of the longitudinal component of the cutting force close to those readings recorded experimentally with a 95% confident interval.

Abstract: Majority of automobile and appliance components are made by deep drawing sheet metal process. So these growing needs demand a new design methodology based on metal forming simulation. With the help of metal forming simulation we can identify the problem areas and solutions can be validated. The aim of this research is to develop techniques that would reduce the amount of time spent during the tool qualifying stage. In this paper the draw tools on Automobile outer clutch shell surface are designed by the precise die surface at different dimensions and draw processes is analyzed with appropriate simulation parameters. From this we got the most reliable results. The compression with the tryout part shows that the simulation process can accurately predict the formability problems.

Abstract: In the medium of hydrochloric acid, Vitamin C (VC) reacts with Se (VI) to form Se particles. The particles exhibit four resonance scattering peaks at 340, 400, 470 and 520 nm. VC concentration is proportional to the I_340nm in the range of 0.05 to 4.0μg ml^-1. Based on this fact, a new resonance scattering spectral (RSS) method has been proposed for the determination of VC with a detection limit of 0.01μg ml^-1. This method was used to determination of VC in pharmaceuticals, synthetic samples with satisfactory results.