Effect of different oxygen species originating from the dissociation of O2, N2O and NO on the selectivity of the Pt-catalysed NH3 oxidation

An effect of oxygen species formed from O₂, N₂O and NO on the selectivity of the catalytic oxidation of ammonia was studied over a polycrystalline Pt catalyst using the temporal analysis of products (TAP) reactor. The transient experiments were performed in the temperature range between 773 and 1073 K in a sequential pulse mode with a time interval of 0.2 s between the pulses of the oxidant (O₂, N₂O and NO) and NH₃. In contrast to adsorbed oxygen species formed from NO, those from O₂ and N₂O reacted with ammonia yielding NO. It is suggested that the difference between these oxidising agents may be related to the different active sites for dissociation of O₂, N₂O and NO, where oxygen species of various Pt-O strength are formed. Weaker bound oxygen species, which are active for NO formation, originate from O₂ and N₂O rather than from NO. These species may be of bi-atomic nature.     

低层建筑抗风设计方法比较与研究

土木工程设计中,最有影响和最易引起工程结构失败甚至破坏的首推风荷载.最近几年风灾严重,尤其是风灾导致的低层建筑损失更是惨重.而国际上发达国家的风荷载规范则在不断变化之中,尤其是对轻型钢结构的抗风设计.因此本文有必要对各国低层轻型钢结构抗风设计方法进行研究.本文分别对中国、日本、美国等国家关于抗风设计方法进行比较,并针对风压系数计算一个实例,最后与风洞试验结果进行对照,对中国抗风设计方法进行研究与探讨.     

胶印机色墨转换实验及数据库开发

在胶印机色彩检测与控制系统中,色墨转换实验数据对色墨转换算法的研究及色彩控制的准确度具有重要的作用.开放式色墨转换工艺数据库便于用户根据自己的需要添加新的色墨转换数据,提高色彩检测与控制系统的通用性及控制精度.在确定色墨转换实验方案的基础上,在北人集团的对开四色胶印机上进行了色墨转换实验;综合考虑影响色墨转换实验的各因素,设计了色墨转换工艺数据库;并采用Visual C++及MySQL开发了开放式色墨转换工艺数据库管理系统,用户可以方便地进行数据的查询、添加、删除及修改等操作.     

S-P混杂纤维对混凝土长期性能与耐久性影响

采用对比的试验方法,研究并讨论了钢纤维、聚丙烯纤维及其混杂对混凝土长期性能及耐久性的影响.研究结果表明,用不同尺度、不同性质的钢纤维与聚丙烯纤维按二元混杂以总体积率0.9%掺入高性能混凝土中,明显改善了水泥混凝土的长期性能,90d干缩值减少36.6%,200d徐变度降低45.4%,并可显著提高混凝土的耐久性能,相对渗透系数降低79.03%,氯离子渗透系数降低30.5%.     

倒卵叶五加多糖提取分离工艺的优化

通过正交试验优化了倒卵叶五加多糖的提取分离工艺．采用水提醇沉法提取多糖,通过单因素试验和L9（3^4）正交试验对影响多糖提取分离工艺的各因素进行了研究．所优化的倒卵叶五加多糖最佳提取分离工艺为用10倍量水提取3次,每次1h;醇沉分离工艺最佳条件为醇沉时乙醇体积分数859／6,料液比1：2（g／mL）,静置14h．实验证明,该提取分离工艺稳定可靠．     

循环动载作用下层状介质长期沉降计算方法

针对循环动载作用下交通基础设施长期沉降,研究解决在移动条形荷载作用下层状介质动应力和循环加卸载条件下层状介质残余应力、永久应变与残余沉降计算2个基本问题.采用Fourier积分变换与递推矩阵方法,依据平面问题动力微分方程、边界条件与层间连续条件,推导得到移动条形荷载作用下的层状介质动应力解析解.考虑应力水平和应力路径的影响,提出新的永久应变经验公式,通过卸载条件下附加永久应变的弹性边值问题求解,获得循环动载作用下层状介质残余应力与长期沉降的表达式.针对3种不同路基半刚性基层沥青路面环道试验,研究路表残余长期沉降变化规律;通过实测值和预测值对比分析验证了本文方法的合理性和可靠性.     

Experiments and reaction characteristics of liquid phase simultaneous removal of SO<Subscript>2</Subscript> and NO

Experiments of simultaneous removal of SO₂ and NO from simulated flue gas, using NaClO₂ solution as the absorbent, were carried out in a self-designed bubble reactor, and high simultaneous removal efficiencies of SO₂ and NO were obtained under the optimal experimental conditions. The mechanism of simultaneous removal based on NaClO₂ acid solutions was proposed by analyzing the removal products. Possibility and limitation of the desulfurization and denitrification using NaClO₂ acid solutions were calculated by thermodynamic methods. Experimental results of reaction kinetics for simultaneous desulfurization and denitrification indicated that the oxidation-absorption processes of SO₂ and NO were divided into two zones, namely the fast and slow reaction zones. In the slow reaction zones both were zero order reactions, and in the fast reaction zones, the reaction order, rate constant and activation energy of SO₂ reaction with absorbent were 1.4, 1.22 (mol·L⁻¹)^−0.4·s⁻¹ and 66.25 kJ·mol⁻¹, respectively, and 2, 3.15×10³ (mol·L⁻¹) ⁻¹·s⁻¹, and 42.50 kJ·mol⁻¹ for NO reaction, respectively. Supported by the National High-Tech Research and Development Program of China (“863” Project) (Grant No. 2007AA061803)     

一种新的InSAR基线估计方法

针对InSAR技术中基线估计误差对DEM精度的影响,从传统的基线估计方法入手,提出了一种新的估计基线参数的方法,并用仿真实验做了论证.结果表明,该方法比以往传统的方法得到的基线参数的精度更高,运算速度更快,应用范围更加广泛.     

基于季节长记忆双自回归模型的日径流模拟

传统时间序列模型无法同时考虑径流序列的长记忆性和时变波动性,且模型参数限制严格,从而使日径流序列模拟受到限制,影响径流模拟预测精度。本文提出了同时考虑非平稳性、季节性、长记忆性和时变波动性的新型双自回归模型(WOA-SFIDAR),并与经典长记忆波动率模型(SFIAR-GARCH)进行对比,选取渭河流域4个水文站日径流序列进行模拟验证。结果表明：WOA-SFIDAR模型的模拟能力优于SFIAR-GARCH模型,模拟结果很好地保持了日径流过程的统计特性。7、8月份模拟均值误差相对较大,WOA-SFIDAR模型的误差范围(5.72～32.56)低于SFIAR-GARCH模型(7.42～48.02)。WOA-SFIDAR模拟逐月变差系数(C_v)和偏态系数(C_s)与实测序列统计值间偏差范围为0～0.51和0.02～1.31,优于SFIAR-GARCH模型(0.02～0.56和0.06～1.52);模拟结果能够保持日径流序列自相关系数(ACF)的变化趋势,且随滞时的增加,实测序列与模拟序列的ACF差距减小。文中模型扩展了水文随机模拟方法,可为日径流模拟...     

基于多因素改进型PSOSVM算法的中长期负荷预测

中长期负荷预测作为电力规划与调度中的重要一环,其影响因素有着多样性和不确定性等特点.选取支持向量机作为中长期负荷预测的核心算法,筛选多种区域宏观经济因素,利用粒子群(PSO)寻优与循环寻优的改进型算法对支持向量机(SVM)的参数进行优化及负荷预测.仿真结果显示,改进型PSOSVM算法有着较高的预测精度.