Applied Mechanics and Materials Vols. 448-453

Abstract: This paper presents Feedforward Neural network (FFNN) and Elman network controllers to control the maximum power point tracking (MPPT) of photovoltaic (PV). MPPT is a method used to extract the maximum available power from photovoltaic module by designs them to operate efficiently. Thus, cell temperatures and solar irradiances are two critical variable factors to determine PV output powers. The performances of the controller is analyzed in four conditions which are i) constant irradiation and temperature, ii) constant irradiation and variable temperature, iii) constant temperature and variable irradiation and iv) variable temperature and irradiation. The proposed systems are simulated by using MATLAB-SIMULINK. Based on the results, FFNN controller has shown the better performance compare to the Elman network controller during partial shading conditions.

Abstract: In order to find the strains which can produce high ethanol yield as well as tolerate inhibitors on the lignocellulosic hydrolysates for developing the renewable bioenergy, the sepecial yeast must be explored. After acclimatizing 23 days and using five different acclimation media with sequential increase in the concentration of inhibitory compounds , a kind of saccharomyces cerevisiae strain resistant to inhibitors was obtained . When the yeast resistant to drug and the parent strain grew in the same media which contained several inhibitory compounds 3.2 g/L acetic acid , 0.8 g/L furfural , 0.4 g/L formic acid , the new yeasts maximal ethanol yield can reach 0.428 g/g , up to 85.6% of theoretical ethanol yield. Compared with drug resistant yeast , the parent strains maximal ethanol production yield only can reach 0.246 g/g , up to 52.8% of theoretical ethanol yield . After 5 continuous ages , the average ability of producing ethanol was stable. Compared with parent strain, the yeast resistant to drug had good ability to ferment glucose and produce ethanol as well as tolerate inhibitors .The new yeast has extensive application prospect in the bioethanol production.

Abstract: Chinese Spicehush (Lindera communis) is widely distributed in China. In this paper, the biodiesel production from Lindera communis seed oil by immobilized lipase Lipozyme TLIM and Novozym 435 was studied. The effects of reaction time, segmented addition of methanol, lipase loading, organic solvents and ultrasonic on the transesterification were compared. In addition, the stability of lipase was also studied. The results show that mixture of Lipozyme TLIM 3% and 1% Novozym435 not only improves the catalytic activity, but also reduces the cost of using the enzyme. The yield of methyl esters is 90.8% after reaction of 12 h.

Abstract: Based on comparison analysis of transcriptome sequencing data, potential genes responsible for xylose fermentation to ethanol were screened and chosen from two model yeast strains of Candida tropicalis and Candida shehatae. Thereafter, key genes were indentified from these candidate genes by the combined method of quantitative real-time PCR detection and metabolism pathway analysis. These genes regulatory mechanism on sugar metabolic pathway were further investigated and illustrated. Four key genes responsible for xylose fermentation to ethanol are determined and confirmed finally as follows: xylose reductase, xylitol dehydrogenase, high-affinity glucose transportor and pyruvate kinase.

Abstract: This paper investigated the effects of mesophilic temperature (35°C) and thermophilic temperature (55°C) on the hydrolysis and acidification phase in the process of organic wastes anaerobic digestion. Here, the organic wastes refer to the mixture of corn straw and pig manure in this paper. The results show that pH value is negatively correlated with volatile fatty acids (VFAs) concentration, throughout the process both the VFAs concentration and its maximum of mesophilic temperature are bigger than that of thermophilic temperature, but it takes longer time to reach the maximum; the total solids (TS) removal rate of thermophilic temperature is 31.85% and the mesophilic temperature is 27.33%, but it needs to consume more energy to maintain a high temperature state. The above results suggest that the mesophilic is more advantageous than thermophilic temperature in the treatment of corn straw and pig manure co-digestion, but the post-disinfection treatment is needed.

Abstract: The mixed materials come from Beijing Daxing District, corn stalks as the main raw material, peanut shells and wheat straw as affixation. Combustion characteristics of mixed materials are studied by using Thermogravimetric analyzer and combustion dynamics studied by using Coats-Refern method to offer practical and theoretical data for crop straw combustion and Densified . Studies have shown that Combustion curve of three samples have two distinct peaks, divided into water evaporated to dryness, and the combustion of volatiles, fixed carbon combustion and burnout four basic stages and lied a larger overlapping area in the entire combustion stage, That combustion characteristics and kinetic parameters of mixed materials are influenced by adding peanut shells, and less affected on adding wheat straws.

Abstract: Cellulose is regarded as a kind of biomass with high quantity, the proper utilization could realize energy recovery and high-value product recovery. Cellulose degradation is of great importance for its utilization. This article introduced the isolation, characteristic and the mutual effect of compound cellulose degradation bacteria, the composition, the effect and mechanism for cellulose hydrolysis were also introduced. Rumen microbial were taken as example for its utilization in cellulose degradation. The relationship between anaerobic and aerobic were discussed to evaluate their mutual effect. It is proved that the aerobic microorganism could help to provide the anaerobic condition for the bacteria, while the anaerobic could reduce the product inhibitor effect.

Abstract: Thermogravimetric analysis (TGA) was employed to study the effects of two different atmospheres (nitrogen and mixed biomass gasification gas) on the pyrolysis of rice husk, corn stalk and pine wood. Kinetic parameters were calculated based on the experiment data. The results indicated that TG and DTG curves moved to higher temperature range and the characteristic temperatures ascended as the increasing of the heating rate. Moreover, the three biomass materials exhibited similar pyrolysis behaviors under the two different atmospheres, but the activation energy values of the pyrolysis under mixed biomass gasification gas were higher than those under nitrogen.

Abstract: The development and utilization of clean and renewable marine energy sources will be a way for the development of economy. Although on a global scale the advantages of renewable energy are not in doubt, the impacts on the local environment must be carefully considered. The sonar devices could be used to monitor the underwater environment around the marine renewable energy device. In this paper, a Multi-beam Echo Sounder is introduced. And the measured results in a lake are given, which are shown that this sonar could detection the fish effectively.

Abstract: A 2 D CFD model was established to simulate sawdust gasification in an entrained flow gasifier using Ansys Fluent software. Syngas composition, syngas yield and syngas LHV were evaluated. The simulated syngas compositions were in agreement with the experiment results. The relative errors of syngas yield and LHV varied in the ranges of 2-15% and 1-9%, respectively. The results showed that the numerical model established in this study can be applied to simulate biomass gasification in entrained flow gasifier.