Advanced Materials Research Vols. 347-353

Abstract: This paper used the method of non-symmetric fuzzy optimization design for the fuzzy optimization design of pressure angle and addendum coefficient of high addendum gears. According to the constraints, the value range of parameters , and fuzzy constraints in closed figure to establish the objective function of fuzzy optimization design for engaging angle . Then equivalently transformed it to the normal optimization mathematical model, and then solved it following the conventional method of optimization design. Calculated by the optimization design: for the given sum of teeth number and transmission ratio, when the addendum coefficient is 1.25 or 1.3, the pressure angle is 20 º, the engaging angle is at the peak or close to the peak, performance of high addendum gears can basically achieve the optimal or suboptimal, which can meet design requirements.

Abstract: The anaerobic digestion is an efficient utilization way of crop residues and alkali pretreatment are often used to enhance the degradation. Alkali pretreatment based on Ca(OH)₂ addition of rice straw was studied.The tests of 3 g/l, 9 g/l Ca(OH)2 addition had an significant effect on enhancing solubilization and rapid acidification, the results were 1521.2 gCOD/l and 935 ml biogas yield of 3 g/l Ca(OH)₂ addition, 1600.7 gCOD/l and 1200 ml biogas yield of 9 g/l Ca(OH)₂ addition , compared to 405.5 gCOD/l and 1162 ml of control( 0 g/l Ca(OH)₂ addition) . The results also showed that tests of 15 g/l , 21 g/l of Ca(OH)₂ addition were entirely inhibited to biogas yield. The result of the present work implied that although alkali pretreatment to rice straw can significantly enhance solubilization, the inhibition to methane yield was liable to occur.

Abstract: This paper analyzes the construction and control principle of Thyristor Switched Capacitor(TSC) and Active Power Filter(APF) integrated device. An harmonics detection method based on the instantaneous reactive power theory is also discussed. This method is effective to apply to TSC&APF integrated device and can get better result to eliminate the harmonics and compensate reactive power. A new integrated device which consists of TSC and APF is developed with this method. The application in the automobile industry shows that this device is correct and effective. It is a favorable model of improving the power quality and save the energy.

Abstract: This article mainly studies the effect of pretreatment in high temperature on reducing sugar content in cow dung waste water in different conditions. Based on the single-factor research, this experiment chooses three factors-temperature, pH value and pretreatment time as independent variable, reducing sugar content as response variable to conduct the response surface experiment, adopts Box—Behenken method to carry out experimental design in order to study the effect of each variable and their interaction on reducing sugar content in waste water. Through the experiment and fitting analysis, the second degree polynomial regressive equation model is retained, and the best pretreatment condition is calculated as this: pretreatment time is 5 days, pH value at 5.9 and temperature at 49°C. Finally the experiment shows that the maximum reducing sugar content in cow dung under this condition is 1.2789 mg/mL.

Abstract: China is a large agricultural country that has abundant biomass resource which can be generated biogas for heating and lighting. To improve biogas production efficiency of human excreta, which is a main kind of material in household biogas use, a laboratory-scale simulated experimental using self-designed constant temperature anaerobic fermentation equipment was conducted in our study. The results showed that increase of temperature can improve biogas generation efficiency of human excreta, and the other way is to mix the human excreta with other materials especially with the high C materials. Compare with the high costing of increase temperature, co-digestion with wheat straw has obvious advances: the crop straw can easily obtain and both wastes can be handled in the anaerobic fermentation process. The co-digestion developed in our study may be applicable to human excreta with other crop straws such as corn straw for biogas production.

Abstract: In this study the dynamic Smagorinsky model (DSM model) and an algebraic model for the subgrid turbulent kinetic energy have been implemented into KIVA3VLES code to investigate the atomization and evaporation processes of diesel spray in a constant volume vessel. Based on the experimental results of the liquid and vapor phase distributions as well as the results obtained by the differential subgrid scale kinetic energy (K-equation) model, the paper reveals the influence of the turbulent kinetic energy model on the fuel spray prediction. Computational results show that by combining the DSM model and the algebraic subgrid turbulent energy model, the turbulent diffusion of droplets can be reasonably simulated, the liquid penetration and the predicted liquid and fuel vapor mass fraction contours are close to the experiment results. At the same time, the turbulent kinetic energy given by the DSM model is in agreement with the results by the K-equation model, but with less computational cost..

Abstract: The object of this study is to provide the scientific basis of biogas industry with agricultural residue straws as energy biomass. The biogas productivity potential experiment and reactor amplification experiment are carried out to study biogas yield from different agricultural straws including wheat straw, corn straw, peanut straw, soybean straw as well as rice straw, and the relationship between biogas yield and the anaerobic reactor volume with wheat straw as the substrate and with biogas slurry as a source of microorganisms under room temperature conditions (35°C). Micro-aerobic pretreatment fermentation technology is used to treat the agricultural straws. The batch anaerobic digestion technology and drainage collection process are used. The results show that the order of biogas yield from high to low is wheat, rice, corn, peanut and soybean straw. The utilization of peanut straw is the largest, followed by rice, corn, soybean and wheat straw. With wheat straw as the substrate amplification test reactor, gas production of 2.5 L and 1 L reactor is similar, and gas production rate and daily gas production of 2.5 L reactor is about 3 times than that of 15 L reactor.

Abstract: This paper focuses on investigating the characteristic modes and structures in non-premixed swirling methane/air flames. Using the Particle Image Velocimetry (PIV) technique, the experiment measured the velocity distributions of the swirling flame. Cold flow conditions have been included to provide a picture of the flow field and to demonstrate the modifications induced by combustion. The characteristic lengths, velocity vectors, streamlines, and velocity distributions are presented and discussed. The experiment shows that a large spatial separation at the exit between the central and swirling annular jets can expedite the formation of a recirculation zone. Complex flow structures are found in the recirculation zone. Moreover, the differences between cold swirling flow field and combustion swirling flow are analyzed at length. The data from this experiment is helpful for optimization of the non-premixed burner design, and can be established as benchmarks for the development and validation of combustion numerical simulations.

Abstract: Three reasons of the deviation of the fuel injection quantity for the electronic fuel injection (EFI) motorcycle engine during the transient conditions were analyzed, including the presence of fuel injection dead time, the engine load measurement deviation and the existence of fuel film attached to the inlet pipe wall. The control strategy of fuel film compensation was studied at conditions of starting, acceleration and deceleration, which was based on the changes of engine velocity, inlet air pressure and inlet air temperature. During the transient condition, the basic fuel film compensation and correction coefficient were calibrated at motorcycle dynamometer, and the modified fuel film compensation MAP were achieved correspondingly, in order to keep the excess air coefficient stable.

Abstract: Endo-1,4-β-xylanase (E.C.3.2.1.8) is a family of glycoside hydrolase. It is capable of hydrolyzing the backbone of substituted xylan polymers into fragments of random size. Due to this ability, xylanase can serve the degradation of lignocellulose, and facilitate the application of xylan. Cell-surface display of enzymes is one of the most attractive applications in yeast. It is a promising utilization in constructing the whole-cell biocatalyst of xylanase. For this purpose, a cDNA sequence of endo-1,4-β-xylanase B (XylB) from Aspergillus niger BCC14405 was optimized and synthesized according to the codon bias of Saccharomyces cerevisiae. The genes encoding galactokinase (GAL1) promoter, α-mating factor 1 (MFα1) pre-pro secretion signal, fully codon-optimized XylB, the 320 amino acids of C terminal of α-agglutinin, alcohol dehydrogenase (ADH1) terminator and kanMX cassette were amplified and cloned into YEplac181 to construct a cell-surface display vector called pGMAAK-XylB with α-agglutinin as an anchor. Then pGMAAK-XylB was transformed into S. cerevisiae. The results show XylB was immobilized and actively expressed on S. cerevisiae. Meanwhile, a secretion expression plasmid was also constructed using the above elements except α-agglutinin as a control strain in the study of characteristic of XylB. After an induction of 48 h by 2% galactose, the activity of displayed XylB reached 63 U/g dry-cell weight. The optimal pH of displayed XylB has changed from 5 to 6 and the optimal temperature has changed from 50 °C to 60 °C, comparing to the recombinant secretion XylB.