苹果园的测土配方施肥技术

在一定的目标产量区间里,苹果园氮、磷、钾肥的施用量与土壤中氮、磷、钾养分含量呈负的线性关系：根据烟台地区苹果生产实践,总结提出了养分施用量与土壤养分含量、目标产量的线性函数公式,可方便求得苹果的适宜基、追施N、P2O5、K2O量。     

快速浸出法提取印楝素浸膏

比较了微波法、超声波法、常规溶剂浸提法和快速浸出法4种方法提取印楝种子中印楝油、印楝素浸膏得率和浸膏中印楝素A、印楝素B的质量百分含量。快速浸出法提取总耗时0．5h,印楝油得率31．9％,印楝素浸膏得率3．39％,浸膏中AzadirachtinA含量8．99％、AzadirachtinB含量2．92％。快速浸出法耗时少,得率高,具有较多优势。测定了快速浸出法提取印楝素不同萃取时间下印楝种粉的粒度,发现物料粒度不断减小是达到快速萃取目的的一个重要因素。     

Thermal degradation behavior of PMMA synthesized by emulsifier‐free emulsion polymerization with a Cu2+/HSO3− redox system

In this study, poly(methyl methacrylate) (PMMA) latex was synthesized in an emulsifier‐free emulsion polymerization at 60°C using a Cu²⁺/HSO redox initiator system with different concentrations of Cu²⁺. The experimental results showed that the monomer conversion reached above 90% for all systems. Zeta potential was all negative due to the bonded bisulfite ion and the magnitude was greater than 30 mV, providing the stability of PMMA emulsion. The morphology of the latex observed by scanning electron microscope revealed a uniform particle size, and the average particle size increased from 181.9 to 234.2 nm as the Cu²⁺ ion concentration increased from 2.0 to 6.0 mM in 1M of MMA solution. Thermal degradation behavior of synthesized PMMA was studied by thermogravimetric analysis, in which a two‐stage degradation behavior was observed. These two stages were found to be caused by the degradation of unsaturated end group (PMMA? CR?CH₂) and saturated end group (PMMA? H), respectively. In addition, the higher the concentration of Cu²⁺ ion, the greater the proportion of PMMA? CR?CH₂ in the final product, and in turn rendering more weight loss in the first‐stage degradation. The copper ion not only played a role in the redox initiation, but also acted as a chain transfer agent to terminate growing polymer chains, thus producing PMMA? CR?CH₂. The apparent activation energies of the first stage (E_a1) and second stage (E_a2) were calculated by Ozawa's and Boswell's method. The results showed that E_a1, representing the degradation of PMMA‐CR?CH₂, was lower than E_a2 for the degradation of PMMA‐H. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of high char yield polybenzoxazine/polyarylacetylene blends for resin‐transfer molding

Benzoxazine precursors (BOZP), 6,6′‐bis(2,3‐dihydro‐3‐(3‐ethynylphenyl)‐4H‐1,3‐ benzoxazinyl)ketone and 6,6′‐bis(2,3‐dihydro‐3‐(3‐ethynylphenyl)‐4H‐1,3‐benzoxazinyl)ether were synthesized and characterized by Proton nuclear magnetic resonace (¹H‐NMR) and Fourier transform infrared spectroscopy (FTIR). The polyarylacetylene (PAA) was synthesized through thermal polymerization of diethynylbenzene, and characterized by ¹H‐NMR, FTIR, and Differential Scanning Calorimetry (DSC). The BOZP/PAA blends were prepared with different contents of PAA, and their viscosity was measured using NDJ‐79 rotating visometer. The curing behavior of BOZP/PAA blends was characterized by DSC. The thermal stability of cured BOZP/PAA blends was studied using Thermogravimetric Analysis, the results show char yield at 800°C was in the range of 78–84%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

微波辐射下一锅法合成3,4-乙撑二氧噻吩类化合物

首次从2,3-二甲氧基-1,3-丁二烯衍生物出发,微波辐射下采用一锅法成功合成了一系列3,4-乙撑二氧噻吩类化合物.实验表明,该法具有反应条件温和、收率高和操作简单的优点.3,4-乙撑二氧噻吩类化合物的结构经 ~1HNMR 、~13CNMR、IR和元素分析进行了表征.也讨论了原料的量、催化剂和溶剂对3,4-乙撑二氧噻吩(EDOT)收率的影响.     

向家坝水电站重力坝深层抗滑稳定性研究

针对重力坝深层抗滑稳定性问题,结合向家坝水利水电工程,采用非线性有限元法与刚体元法,分别对失稳判别准则、数值分析的本构关系选择、安全系数计算方法、坝体体型与深层抗滑稳定性的关系等方面进行了具体研究.通过分析得出,体型对坝体深层稳定性影响较大,塑性区贯通破坏准则与强度储备安全系数法较为适合重力坝深层抗滑稳定分析,数值模拟中的屈服准则宜采用Druker_Prager型屈服准则中的内切圆准则.最后,对重力坝设计与深层抗滑稳定性分析方法的前景进行了展望.     

A thermodynamic analysis of the activated sludge process: Application to soybean wastewater treatment in a sequencing batch reactor

A bioenergetic methodology was integrated with a modified activated sludge model No.1 (ASM1) to analyze the activated sludge process, with the treatment of soybean‐processing wastewater as an example. With the bioenergetic methodology established by McCarty and coworkers, the microbial yield was predicted and the overall stoichiometrics for biological reactions involving the key chemical and biological species in activated sludge were established. These obtained parameters were related to the ASM1 model, which was modified after coupling the biological reactions in activated sludge with electron balances. This approach was able to approximately describe the treatment of soybean wastewater by activated sludge in a sequencing batch reactor in terms of substrate utilization, biomass growth, and the elector acceptor consumption. Such an attempt provides useful information for accurate modeling of the complex activated sludge process. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

防屈曲支撑框架与普通支撑框架的抗震性能比较

利用有限元软件ABAQUS6.5对普通中心支撑框架结构、采用低屈服点钢材的防屈曲中心支撑框架结构模型进行了大震时程分析。发现采用低屈服点钢材的防屈曲支撑,不仅解决了支撑杆件的失稳问题,而且明显减小了结构位移等响应,优势明显。     

对数螺旋线破坏下加筋边坡地震稳定分析

以拟静力法的理论框架分析了土工合成材料加筋边坡对数螺旋线破坏模式下的地震稳定性,整个计算过程采用极限分析的动力学理论,推导出的表达式能够容易地计算出地震荷载作用下为阻止边坡破坏所必需的加筋力和屈服加速度系数。     

屈服面角点奇异性的非平滑处理对塑性应变的影响

Mohr-Coulomb屈服面的边界角点奇异性问题,使得屈服面在这些部位的微分出现不连续现象,给数值分析带来了诸多困难,针对此问题,平滑及非平滑处理方法得以应用,其中,非平滑处理方法中的回代求导法和塑性应变增量求和法等因易于实现而应用较多。这些方法精度的研究多相对于某些典型算例而进行的,而对于塑性应变的发展遵循何规律,非平滑处理方法对塑性应变产生何影响,如何评价这种影响效应等等问题尚未在理论上被深入研究。为此,在传统塑性位势理论的框架内对塑性剪应变的发展规律,以及通过非平滑处理后塑性剪应变的发展规律进行了理论研究。研究发现,在角点奇异性屈服面的非平滑处理方法中,最终推导出的塑性剪应变出现不连续现象。通过对这一现象进行的理论研究和定量分析,结果表明:非平滑处理对塑性应变存在影响效应(即不连续效应),故对于具体问题,应具体分析这些方法的影响效应,具体评估其计算结果的可靠性和对相应问题的适用性,以便正确选择所采用的处理方法。