Yield Composition Analysis of Vine Tip of Leaf-vegetable Sweetpotato

Total yields of vine tip of seven varieties of Leaf-vegetable sweetpotato during 2006-2007 were investigated; proportions of the weights of leaf, leaf stalk and stem in total vine tip yield and their changes among varieties and during topping stages were studied. The results showed that vine tip yields of sweetpotato were significantly different among either varieties or topping stages; leaf yield accounted for about 51% of total vine yield, and changes in leaf yield among topping stages were higher than that among varieties; while yields of leaf stalk and stem each accounted for 25% of total vine tip yield, their changes among varieties were higher than those among topping stages. These results revealed the yield composition of vine tip of Leaf-vegetable sweetpotato, which provided scientific references for breeding and cultivating new Leaf-vegetable sweetpotato variety and its industrialization.

An Application of the Modified Shear Lag Model to Study the Influence of Thermal Residual Stresses on the Stiffness and Yield Strength of Short Fiber Reinforced Metal Matrix Composites

The modified shear lag model proposed recently was applied to calculate thermal residual stresses and subsequent stress distributions under tensile and compressive loadings. The expressions for the elastic moduli and the yield strengths under tensile and compressive loadings were derived which take account of thermal residual stresses. The asymmetries in the elastic modulus and the yield strength were interpreted using the derived expressions and the obtained results of the stress calculations. The model predictions have exhibited good agreements with the experimental results and also with the other theoretical predictions

A New Modification to Shear Lag Model as Applied to Stiffness and Yield Strength of Short Fiber Reinforced Metal Matrix Composites

A new modification for the shear lag model is given and the expressions for the stiffness and yield Strength of short fiber metal matri×composite are derived. These expressions are then compared with our experimental data in a SiCw/Al-Li T6 composite and the published experimental data on different SiCw/Al T6 composites and also compared with the previous shear lag models and the other theoretical models.

Release Characteristics of Release-controlled Nitrogen Fertilizer in Winter Wheat on Dry Land

[Objective] The aim was to study the release characteristics of different release-controlled fertilizers, as well as their effects on wheat growth and develop- ment under water stress. [method] With phosphorus-potassium fertilization and opti- mized fertilization （OPT） as the control, the release characteristics of 4 kinds of re- lease-controlled nitrogen fertilizers （A, B, C and D） coated with different materials were studied. [Result] Under the same phosphorus and potassium levels, the re- lease-controlled nitrogen fertilizers A and B significantly improved the yield of wheat. Spike number is the main reason leading to the difference in yield. The fertilizers A and B were released by 44.4% and 46.3% before winter, released by 72.1% and 69.8% at the jointing stage, and related by 88.0% and 91.5% in the harvest period, meeting the nitrogen requirement of dryland wheat across the growth period. Com- pared with OPT, the nitrogen accumulation amounts in treatments A and B were increased by 1.39 and 2.09 kg/667 m2, the nitrogen use efficiencies were increased by 8.66% and 13.04%, and the nitrogen partial factor productivities were increased by 9.00 and 7.22 kg/kg, respectively. [Conclusion] Among the 4 kinds of fertilizers, A and B were considered as the optimum release-controlled nitrogen fertilizers for winter wheat on dry land.

Effect of Zinc Methionine Supplementation on Productive Performance of Lactating Friesian Cows

Twelve lactating Friesian Cows with body weight of 450 to 550 kg and in the second to fifth lactating season were used after 8 weeks of cal- ving in a complete switch-back design. The cows were fed a basal ration of 35% concentrate feed mix-ture with 40% berseem and 25% rice straw （ on a dry matter （DM） basis） without supplementation （ G1 ） or supplemented with 5 and 10 g zinc methionine per head per day （G2 and G3, respectively）. Nutrient digestibility coefficients and nutritive values were significantly increased （P 〈0.05） by zinc methionine supplementation. Cows in G2 had the highest feed intake of total digestible nutrients （TDN） and digestible crude protein （DCP）, followed by Ga and G1, respectively （ P 〈 0.05 ）. The ruminal total volatile fatty acid concentration increased and ammonia nitrogen decreased significantly （ P 〈 0.05 ） by zinc methio-nine supplementation. Cows in G3 showed the highest plasma total protein, albumin, and globulin concen- trations （ P 〈 0.05 ）. Zinc methionine supplementa- tion led to significant decreases （ P 〈 0.05 ） in the activities of aspartate aminotransferase and alanine aminotransferase. A significant increase （ P 〈 0.05 ） was observed in the milk yield for G2 （2.54 kg/d or 18. 1% ） and G3 （ 1.95 kg/d or 14.2% ） compared with the control group. The corresponding increase in 4% fat-corrected milk （FCM） was 2.85 and 2.03 kg/d （21.63% and 15.74% ） for G2 and G3, respectively. Cows in G2 had the highest fat, total protein, and total solids contents, and the yield of all milk constitu- ents and animals in G3 showed the highest lactose, solids-not-fat, and ash contents. Zinc methionine sup- plementation improved feed conversion, reducing the quantities of DM, TDN, and DCP required to pro- duce 1 kg of 4% FCM （P〈0.05）. The average dai- ly feed cost per kilogram of 4% FCM decreased and the average income from milk production increased with zinc methionine supplementation （ P 〈 0.05 ）. Quadratic analysis showed that the optimal level of zinc methionine supplementation is 6 g per head per day in terms of milk yield and net revenue.

On the homogenization of metal matrix composites using strain gradient plasticity

The homogenized response of metal matrix composites（MMC） is studied using strain gradient plasticity.The material model employed is a rate independent formulation of energetic strain gradient plasticity at the micro scale and conventional rate independent plasticity at the macro scale. Free energy inside the micro structure is included due to the elastic strains and plastic strain gradients. A unit cell containing a circular elastic fiber is analyzed under macroscopic simple shear in addition to transverse and longitudinal loading. The analyses are carried out under generalized plane strain condition. Micro-macro homogenization is performed observing the Hill-Mandel energy condition,and overall loading is considered such that the homogenized higher order terms vanish. The results highlight the intrinsic size-effects as well as the effect of fiber volume fraction on the overall response curves, plastic strain distributions and homogenized yield surfaces under different loading conditions. It is concluded that composites with smaller reinforcement size have larger initial yield surfaces and furthermore,they exhibit more kinematic hardening.

Molten steel yield optimization of a converter based on constructal theory

Constructal theory is introduced into the molten steel yield maximization of a converter in this paper. For the specific total cost of materials, generalized constructal optimization of a converter steel-making process is performed. The optimal cost distribution of materials is obtained, and is also called as "generalized optimal construct". The effects of the hot metal composition contents, hot metal temperature, slag basicity and ratio of the waste steel price to the sinter ore price on the optimization results are analyzed.The results show that the molten steel yield after optimization is increased by 5.48% compared with that before optimization when sinter ore and waste steel are taken as the coolants, and the molten steel yield is increased by 6.84% when only the sinter ore is taken as the coolant. It means that taking sinter ore as coolant can improve the economic performance of the converter steelmaking process. Decreasing the contents of the silicon, phosphorus and manganese in the hot metal can increase the molten steel yield. The change of slag basicity affects the molten steel yield a little.