基于离散元仿真模拟的螺杆加料机加料性能研究

利用建模软件建立不同螺杆导程、外径以及头数的螺杆结构;在离散元数值模拟仿真软件中建立颗粒模型、设置接触参数后,对不同结构下螺杆的输送过程进行模拟仿真;利用后处理模块对颗粒在输送过程中的受力以及加料机的出口质量流率进行分析,探讨螺杆结构对加料质量的影响规律。结果表明,螺杆导程是螺杆加料机输送效率的主要影响因素,20 mm导程的螺杆输送效率是14 mm导程的15倍左右,但是出料精度有所下降;螺杆间隙是颗粒受力的主要影响因素,间隙的减小会导致颗粒受力的增大,1 mm间隙下的平均受力在1.2×10-2 N左右;双头螺杆导致颗粒输送过程中受力的激增,峰值达到15 N左右,出料效率降低,但是出料稳定性提高。

Test of Feeding Dairy Cows with Chinese Herbal Additive for Improving Production and Quality of Milk

At Baiyin dairy farm, the Chinese herbal additive was added into feed which was then fed to dairy cows from August to October, 2014, and the changes in milk production and quality were observed. The test showed that the additive added into the feed had obvious milk-increasing effect, the milk production was im- proved by 12.67%-17.26%, and the milk quality was improved. The additive has the effects of preventing miscarriage, expelling parasite and preventing diseases. The nutritional components in the feed additive were determined, and the results showed that the contents of protein, crude fat, Ca and P in the additive were 12.29%, 2.66%, 1.8% and 0.22%, respectively.

Quality Management Research on the Purchasing of Food Processing Enterprises

In order to improve the purchased goods quality management level of food processing enterprises, the causes of quality management problems were ana- lyzed, which were classified into four categories, namely, natural toxins in raw ma- terials, quality problems in planting and breeding, quality problems in transportation, quality problems in delivery acceptance. Then, based on the causes, eight measures to improve goods purchasing management were put forward, and graphs were used to illustrate the corresponding countermeasure to each cause. This study is of theo- retical significance for the food processing enterprises to improve the quality man- agement of purchased goods through formulating improvement measures based on their operating states.

Conception of tooling adapted to thixoforging of high solid fraction hot-crack-sensitive aluminium alloys

Thixoforging is a type of semi-solid metal processing at high solid fraction (0.7<φs<1), which involves the processing of alloys in the semi-solid state.Tooling has to be adapted to this particular process to benefit shear thinning and thixotropic behaviour of such semi-solid material.Tooling parameters, such as the forming speed and tool temperature, have to be accurately controlled because of their influence on thermal exchanges between material flow and tool.These thermal exchanges influence the high-cracking tendency and the rheology of the semi-solid material during forming, which affects parts properties and therefore their quality.Extrusion tests show how thermal exchanges influence quality of thixoforged parts made of 7075 aluminium alloys at high solid fraction by modifying process parameters like forming speed, tool temperature and tool thermal protector.Thus an optimum in terms of thermal exchanges has to be found between surface quality and mechanical properties of the part.A direct application is the evaluation of surface quality of thixoforged thin wall parts made of 7075 aluminium alloy.

Phytogenic Feed Additive for Sows： Effects on Sow Feed Intake, Serum Metabolite Concentrations, IgG Level, Lysozyme Activity and Milk Quality

The objective of this study was to investigate the influence ofa phytogenic feed additive （PFA） to late-gestation （d 90） and lactation sows on their reproduction performance. Sixty Large White × Landrace primiparous sows were divided into four groups （fifteen sows per group）. The control group was fed with basal diet, the others were fed with basal diet supplemented with 0.02%, 0.04% and 0.06% PFA, respectively. Compared with the control, the sows in 0.04% PFA group had higher feed intake during lactation and higher litter weaning weight （P 〈 0.05）. At farrowing, glucose level in 0.04% PFA sows was higher than the control and sows in 0.02% PFA had the highest IgG content among the treatments （P 〈 0.05）. On day 7 of lactation, serum urea nitrogen contents were lower in response to PFA supplementation compared to the control （P 〈 0.05）. At the same time, sows fed the 0.06% PFA diet increased the lysozyme activity （P 〈 0.05）. The levels of milk lactose and IgG were increased in 0.02% and 0.04% PFA groups （P 〈 0.05）. In conclusion, feeding PFA improved sows and litter performance, serum metabolite concentrations, lgG level and lysozyme activity at postpartum and milk quality.

Effects of Different Processing Modes of Reconstituted Tobacco on Cigarette Quality

In order to explore the most suitable mode for the primary processing model of reconstituted tobacco, another two kinds of conditioning process schemes for reconstituted tobacco were designed based on the existing reconstituted tobacco processing method. Comparative analysis and evaluation were conducted for moisture content uniformity, intrinsic chemical compositions, casing uniformity, blending uniformity and sensory quality of the samples from the three kind of processing modes. The results showed that loosing and conditioning or the vacuum conditioning pretreatment of the reconstituted tobacco could effectively reduce the difference in moisture content during the blending, and improve the casing uniformity and blending uniformity. Moreover, the samples with the loosing and conditioning pretreatment had higher total sugar and reducing sugar contents, which indicated that the loosing and conditioning pretreatment method was more favorable for the improvement of the intrinsic quality of cigarettes. In addition, the three kinds of aromatic components contents of cigarettes using the loosing and conditioning pretreatment were higher,and the casing uniformity, blending uniformity and overall sensory quality of this pretreatment were all superior to that of the other two kinds of reconstituted tobacco pretreatment methods. The contents of total sugar, reducing sugar as well as the three kinds of aromatic components of cigarettes processed with vacuum conditioning pretreatment were all slightly lower than those of the existing methods, but the casing uniformity and blending uniformity were improved, while it showed small difference in the sensory quality with the existing processing method.

Green Product of Liquid Fuel from Plastic Waste by Pyrolysis at 900 ℃

Alternative treatments to convert plastic waste into fuel currently receive great attention from researchers worldwide. The objective of the research is to obtain liquid fuel from pyrolysis of waste plastics that is safe for humans as well as environment, with a heating value and fuel quality meet the standardized compliant. The method used for the research is plastic waste pyrolysis heated at 900 ℃, and the resulting vapor is condensed through a crossflow condenser. The method resulted in a liquid fuel with a calorific value of 46,848 J/g, which is greater than that of plastic waste processing at a temperature of 425 ℃ that is only 41,870 J/g. In addition, the nature of current method for treating plastic waste is considered more secure than that of plastic waste processing at the temperature of 425 ℃. The reason for this is the fact that the percentage of compounds that could potentially be carcinogenic （boric acid and cyclopentanone） is reduced.

Pure Jatropha Oil for Power Generation on Floreana IslandlGalapagos： Four Years Experience on Engine Operation and Fuel Quality

In the small country of Ecuador, all environmental risks of the production and consumption of fossil fuels can be observed by damages through oil exploration in the amazonite rainforest and two tank ship accidents close by Galapagos Islands causing death of 10,000 marine iguanas and other species. Now Ecuador plans to replace all environmentally dangerous diesel generators from all four inhabited Galapagos Islands by a hybrid system using 100% renewable energy for electricity production. Since 2010 a hybrid system of two Jatropha oil generators with an electrical power of 69 kW （kWel） and a photovoltaic plant with an electrical peak power of 21 kW （kWpeak） is successfully providing electricity from renewable energy for inhabitants and tourists of Floreana Island. After more than 15.000 engine operation hours of each engine there is no engine defect. For fuel supply, the so-called ＂Living Fence＂ concept collecting Jatropha seeds by farmers and families from already existing 6,000 km hedges on Ecuadorian mainland was chosen to comply with highest biofuel sustainability standards. The Jatropha oil is produced in a decentralized so-called CompacTropha oil mill container following the ambitious German fuel quality standard DIN51605. Since 2010 Floreana project successfully demonstrates that it is possible to replace diesel gen sets by generators fueled with pure Jatropha oil from decentralized sustainable production.