基于前推回代法的20kV配电网的研究与应用

目前,我国城市电力负荷及负荷密度日益增长的情况和城市配电网现状,10kV电压等级供电暴露出许多不足,供电能力将无法满足需要。10kV电压等级将逐渐向20 kV电压等级过渡。对于10kV升压为20kV电压质量的分析,本文采用前推回代法进行配电网潮流计算。     

Synthesis and characterization of ET(P)S-4 and ET(P)S-10

Phosphorus containing ET(P)S-4 and ET(P)S-10 were synthesized from gels of composition xNa₂O–0.6KF–0.2TiO₂–(1.28 − 4y)xHCl–yP₂O₅–1.49SiO₂–39.5H₂O at 190 °C for 3 days. The XRD patterns are almost identical to the corresponding ETS samples. The presence of phosphorus in the initial gel influences the kinetic parameters of the crystallization process, the morphology and the size of the crystals. The ³¹P-NMR of the samples show that part of the phosphorus is attached at the siliceous surface as dihydrogenophosphate SiOPO(OH)₂ groups and cannot be introduced in a tetrahedral or octahedral framework position.     

微波条件下合成小麦阳离子淀粉

采用微波加热、半干法合成小麦阳离子淀粉,讨论了各因素对小麦阳离子淀粉合成的影响,并通过响应面实验拟合取代度与各影响因素之间的模型函数.结果表明:阳离子淀粉合成最佳条件是氢氧化钠4.2 g,醚化剂10 mL,淀粉乳浓度45%,加热时间9 min.     

Designing against a class of algebraic attacks on symmetric block ciphers

Recently, Courtois and Pieprzyk proposed a class of algebraic attacks on symmetric block ciphers that takes advantage of a previously-unexploited property of substitution boxes, or s-boxes, in the round function. This paper gives a brief overview of this ``overdefined system of equations' (OSE) attack and shows how the attack may be avoided through the use of round functions constructed according to the CAST design procedure. Such round functions contain a variety of protection mechanisms, including s-boxes of large dimension, a circular key-dependent rotation step, and combinations of operators from different algebraic groups.     

土壤尿素酶抑制剂正丁基硫代磷酰三胺的合成

以三氯硫磷为原料,与正丁胺进行亲核取代反应合成中间体正丁基硫代磷酰二氯,再将正丁基硫代磷酰二氯与液氨通过氨解反应合成正丁基硫代磷酰三胺,商品名为Nitrogeny.反应中产生的HCl用三乙胺来吸收.探讨了各种反应因素如反应物的配比,三乙胺的用量,反应时间,温度等因素对抑制剂活性的影响,通过正交实验确定了正丁基硫代磷酰三胺的最佳工艺合成反应条件：n（RNH2）：n（PSCl3）=1：1.2;三乙胺17.5 mL,液氨80 g;反应温度θ1=10 ℃,θ2=0 ℃;反应时间t1=3.5 h,t2=60 min.此时抑制活性达到最大值92.50%.     

Solving a Nonlinear Problem in Magneto-Rheological Fluids Using the Immersed Interface Method

Many applications lead to a nonlinear elliptic interface problem in which the discontinuous coefficient depends on the solution and the material properties. A finite difference method based on Cartesian grids and the maximum principle preserving immersed interface method is proposed for the nonlinear elliptic interface problems discussed in this paper. Numerical experiments against the exact solutions reveal that our method is nearly second order accurate in the infinity norm. The method is applied to study the magneto-rheological field-responsive fluids that contain iron particles. Numerical experiments are performed against the results from the literature.     

密封油系统不置换氢气进行检修的方法介绍

介绍N210-130-535／535氢冷发电机组密封油系统不置换氢气进行检修的方法、注意事项以及优越性。     

高取代度羧甲基淀粉性能及应用研究

研究了高取代度ＣＭＳ（ＤＳ＞０．８）的有关性能特征及其与取代度的联系。研究表明，高取代度ＣＭＳ的抗酸性、抗钙镁离子性、抗温性、抗生物降解性及活性染料得色率等均优于低取代度ＣＭＳ，具有较强的环境适应性和良好的应用性能。高取代度ＣＭＳ用于油田钻井泥浆可抗温至１５０℃，较低取代度ＣＭＳ提高２０℃；高取代度ＣＭＳ可用做活性染料印花糊料，是一种理想的海藻酸钠的代用品；高取代度ＣＭＳ还适用于ｐＨ值较低的介质以及钙镁离子含量较高的介质中；高取代度ＣＭＳ水溶液长时间存放，粘度稳定，不腐败，有利于ＣＭＳ在涂料、油田、饮料、粘合剂等方面的应用。     

关于三角函数有理式积分的探讨

三角函数有理式积分在积分的计算中占有很重要的地位 ,且计算较为复杂 ,属教学中难点。本文就一类三角函数有理式的积分的特殊性及一般性进行探讨 ,特殊性给出一题多解 ,一般性推出求解公式。     

两个分式型不等式的拓广与深化

对两个分式型不等式的参指数α作适当拓广,得到两个一般的分式型不等式,同时对新的分式型不等式的变元ai与bi作巧妙的代换,参指数α与β作适当变形,得到了许多著名的不等式,甚至是其反向不等式,是其加强式,使此类问题系统化、深刻化.