Novel layered pesticide slow/controlled release materials——supramolecular structure and slow release property of glyphosate intercalated layered double hydroxides

Two different interlayer structured glyphosate(GLY) intercalated MgAI layered double hydroxides, as novel pesticide slow/controlled release materials, have been synthesized by co-precipitation method under various reaction pH values. The slow/controlled release properties have been tested in Na2CO3 aqueous solution. The release mechanism has been interpreted on the basis of the ion-exchange between the guest GLY anions in the lamellar host and CO3^2- in the release media, and the diffusion process of GLY anions in the interstice and interlayer of GLY intercalates, i.e.diffusion through the particles, is the rate-limiting step of GLY release process. The GLY intercalate assembled at lower pH, possessing higher interlayer gallery height and vertical monolayered arrangement of guest anions in the interlayer with larger packing density, exhibits better slow release property than that assembled at higher pH. The results reveal that the layered double hydroxides have potential application in the pesticide slow/controlled release area.     

高硫煤——萤石复合矿化剂慢冷对立窑熟料显微结构影响的研究

本文论述复合矿化剂作用下,慢冷对立窑熟料显微结构的影响。通过对实际工厂立窑煅烧情况的分析,找出导致慢冷的原因,提出了改进煅烧工艺的建议。     

一类具有弱增长性的Bolza问题

我们考虑最小值问题(P)min{∫baf(t,u′(t))dt l(u(a),u(b));u∈AC([a,b],Rn)},其中f:[a,b]×Rn→R∪{ ∞}是正规被积函数,l:Rn×Rn→R∪{ ∞}下半连续,AC([a,b],Rn)表示从[a,b]到Rn的绝对连续函数空间.我们将证明最小化算子存在的充分条件.     

空时分组码在时变衰落信道中的性能

从实用性出发,对空时分组码在时变衰落信道中的性能进行了研究.采用SIMULINK仿真工具构造了时变衰落信道的仿真模型,模型由信道、发射端和接收端组成:信道部分由多径Rayleigh信道和高斯白噪声构成;发射端由信源、串并转换器、调制器、空时分组编码器和功率分配模块构成;接收端由信号合并、最大似然译码器、调制解调器和误比特率计算模块组成.仿真结果表明:在平坦慢衰落信道中,STTD性能比单收发系统的性能有很大提高,并且随着SNR的增大,STTD性能的提高幅度增大;在平坦时变衰落信道中,随着最大多普勒频移的增大,STTD性能有所下降,尤其是在大信噪比条件下,性能下降得更明显.     

一类奇异Lienard系统的鸭环的存在唯一性

通过对一类奇异摄动系统的慢散度积分零点的存在唯一性讨论,得到所讨论的系统（L）一定有且只有唯一一个周期解存在,且这个周期解是由快轨道和慢轨道共同构成的鸭环,同时这个周期解是不稳定的．     

奇异摄动系统的二次稳定

奇异摄动对于提高控制系统的分析与设计的精度具有重要的理论意义和应用价值。该文研究了具有快慢尺度的奇异摄动系统的鲁棒稳定性，将正常连续系统的二次稳定的概念推广到奇异摄动系统，并证明了将奇异摄动系统的二次稳定性问题转化为2个正常快慢子系统的二次稳定性问题的等价性。