New discrete Halanay-type inequalities and applications

In this paper, we introduce some new discrete type Halanay inequalities which extend the existing results. On the basis of these inequalities, we discuss the global stability of discrete neural networks with time-varying delays.     

Propensity Rules in Rotational Inelastic Collisions of NH_2(■A_1) under Molecular Beam Condition

Rotationalenergytransfer(RET)isoneofthemostcommonandsimplestinelasticmolecularcollisionalprocesses,anditreflectstheanisotropyoftheinteractionpotentialofthecouplingbetweentheorbitalmotionofthemoleculewithrespecttotheothercollisionpartnerandtherotationalmotion.Also,knowledgeoftheseenergytransferratesarealsoimportantinotherareas,suchaslaserdesignofchemicallaser,etc.Dixon','andAlwahabi'hadstudiedinelasticcollisionsofNH,(A'A,)inaflowingsystem.Butsincetheresultswerenotobtainedundersinglecollision…     

热解析进样气相色谱法测定车间空气中的丙烯酸正丁酯

建立了一种车间空气中丙烯酸正丁酯的测定方法。丙烯酸正丁酯经活性炭吸附后,利用热解析仪解析后直接注入气相色谱仪,氢火焰检测器进行检测。选用高容量、强极性的DB–INNOWAX毛细管色谱柱,以氮气为流动相,流量为1.0 m L/min。丙烯酸正丁酯的质量浓度在1.0~20 mg/m3内与色谱峰面积呈现良好的线性关系,线性相关系数为0.995。丙烯酸正丁酯的检出限为1.0 mg/m3,测定结果的相对标准偏差小于3.0%(n=11),样品加标回收率为99.5%。热解析比溶剂解析法操作简单,避免了较长时间的溶剂洗脱过程,同时减少了样品处理过程中样品的损失。该方法可用于车间空气中丙烯酸丁酯的快速检测。     

Electrochemical Properties of Spinel LiMn_2O_(4-δ)F_δ for Cathode Materials of Secondary Lithium-ion Battery

Inrecentyears,withthedevelopmentofallsortsofcellularphones,camcorders,laptopcomputers,thelithium-ionsecondarybatteriesbasedontheuseofmanganese-lithiumoxideLiMn,O.withlowtoxicityandcostattractmuchattention.ButtheLiMn,O.cathodematerialhasthedisadvantageofpoorstructUralinstabilityasaresultoftheJahnTellereffectcausedbyMn3 .ManyresearchershavemadegreateffortstoimproveitsstructuralstabilitybycanonsubstitUtion,bUtlittlerewardhasbeenreceived.Weadoptedanionsubstitutionasanewmethodtoreachthisgoal,a…     

新型节能添加剂在烧结中的应用研究

烧结料层中碳的燃烧主要有以下特点:料层中燃料较少且分散(含碳量为3～8%);燃烧层的高度比较小(15～50ｍｍ);氧化带较宽,还原带较窄;离开料层的废气中存在着剩余的氧气等。在这种情况下,ＣＯ2不能顺利地被还原成ＣＯ,而ＣＯ有可能遇到空气中的氧进一步氧化,也有可能被铁氧化物氧化。但由于料层下部氧的浓度低,ＣＯ不能完全氧化成ＣＯ2,故二次反应在烧结过程中的发展受到限制。而二次反应对碳粒的燃烧和燃烬至关重要。因此,要强化烧结料层中燃料的燃烧,提高燃料的燃烬率,则必须强化燃料的二次燃烧过程。为了达到上述目的,除了改进设备和工艺…     

Theoretical studies on the hydrogen abstraction reactions of methyl esters with HO2 radical and the following β‐scission reactions

Unsaturated fatty acid methyl esters are ubiquitous in biodiesel fuels. The C = C double bond greatly affects the combustion characteristics of biodiesel, especially its ignition behavior at low temperatures. In this work, we report detailed theoretical study on the mechanism and kinetics of the hydrogen abstraction reactions of linear unsaturated C6 methyl esters with hydroperoxy radical (HO₂), which play a critical role in the low‐temperature combustion of biodiesel. Reaction profiles are obtained via intrinsic reaction coordinate (IRC) analysis including the formation of reactant complexes and product complexes at the entrance and exit channels, respectively. The potential energy surfaces are explored at the CBS‐QB3 level. The following β‐scission reactions of the forming radicals are also investigated at the same level of theory. The high‐pressure limit rate constants for all the reactions in the temperature range from 500 to 2000 K are calculated via conventional transition‐state theory with quantum tunneling effect and fitted to the modified Arrhenius expression.     

Synthesis, cure kinetics, and thermal properties of a novel boron–silicon hybrid polymer

A novel boron–silicon hybrid polymer (PASB) was synthesized from polycondensation between phenylboron dichloride and dichloromethylsilane with Grignard reagent. The structure of PASB was characterized using fourier transform infrared spectra, ¹H-NMR, ¹³C-NMR, and gel permeation chromatography. The curing behavior of PASB was investigated by means of non-isothermal differential scanning calorimetry and the kinetic parameters were determined by the Kissinger’s and Ozawa’s methods, respectively. The results showed that both the methods for calculating the activation energy value gave fairly close results of 104.4 and 107.7 kJ mol^?1, respectively. A reasonable curing cycle for the resin system was also established, which suggested that it was reasonable to choose a curing temperature between T _i0 (452.0 K) and T _f0 (554.0 K). These results can provide theoretical guidance reference for determining the curing of the resin system. The thermal stability of cured PASB resin was studied by means of thermogravimetric analysis under nitrogen atmosphere and the temperature of 5 % mass loss (Td₅) was 610.1 °C, the residue at 1,000 °C was 87.8 %, which showed that the cured PASB resin exhibited excellent thermal properties and made it potentially useful as high performance matrix resin and precursor for ceramics.