考虑导引头多约束的滑翔制导炮弹弹道规划

为提高制导炮弹在大着角情况下导引头捕捉目标的速度,减小末制导起始点角度偏差,在传统制导炮弹方案弹道规划方法(trajectory programming method, TPM)的基础上考虑末制导段,提出一种考虑导引头多约束的弹道规划方法(trajectory programming method-constraints of seeker, TPM-CS)。根据导引头最大探测距离建立末制导起始点约束,根据弹目几何关系和导引头视场角建立攻击路径约束,并建立最小化前置角和控制变量幅值的目标函数。为实现制导炮弹初始弹道倾角、偏角、火箭点火时间、滑翔启控时间、导引头开启时间等参数的最佳匹配,建立了5阶段弹道规划模型,并采用多阶段Radau伪谱法将该弹道规划问题转化为非线性规划问题,最后调用非线性规划求解器SNOPT进行求解。选取不同性能参数的导引头进行仿真,分析了导引头最大探测距离和导引头视场角对方案弹道的影响。将文中提出的弹道规划方法与传统弹道规划方法进行对比仿真,结果表明,相比于传统方法,文中所提方法规划方案弹道的末制导初始角度偏差缩小71.590%,导引头对目标保持照射状态的时间延长6...     

试用布拉班德磨测定小麦出粉率的研究

本试验对不同的品种,不同搭配比例的45份小麦试样,分别用布勒实验磨粉机和布拉班德磨(三种不同操作方法)进行出粉率的测定.结果表明:布拉班德磨直接出粉率及过54GG筛出粉率与布勒实验磨粉机出粉率分别是显著相关和高度相关,相关系数分别为0.72和0.84.证明布拉班德磨的这两种操作方法可替代布勒实验磨粉机用于测定小麦出粉率,并总结出布拉班德磨的这两种操作方法测定小麦出粉率的换算公式.     

Extraction of HNO3 and some ions with tributyl phosphate (tbp)-mixed trialkyl phosphine oxides (trpo)/kerosene

Tributyl phosphate (TBP) and trialkyl phosphine oxides (TRPO) are important extractants. They are widely used in industrial extraction processes, especially in the nuclear power industry. However, both TBP and TRPO suffer from several disadvantages. TBP has a low extractability for trivalent transuranium elements such as Am³⁺ and Pu³⁺ while TRPO has low loading capacity for HNO₃ and UO₂ ²⁺. The extraction of HNO₃ and 20 other ions of importance in the nuclear power industry was studied using TBP-TRPO/kerosene. The loading capacity of UO₂ ²⁺ and HNO₃ in TBP-TRPO/kerosene was determined. The synergistic extraction characteristics of the mixture for Am³⁺ and TcO₄ m were studied. The influence of high-concentration UO₂ ²⁺ on the extraction of Am³⁺, Eu³⁺, Pu⁴⁺, and TcO₄ m was investigated. The experimental results show that TBP-TRPO/kerosene mixtures display both a high extractability for a number of ions and a high loading capacity for UO₂ ²⁺ and HNO₃.     

Back-extraction Of Pu4 + From 20% Tributyl Phosphate – 20% Mixed Trialkyl Phosphine Oxides/kerosene In The Presence Of

Back-extraction of Pu^4 +  from a mixture of 20% tributyl phosphate (TBP) and 20% mixed trialkyl phosphine oxides (TRPO) in kerosene in the presence of UO²⁺ ₂was studied. The back-extractants investigated may be divided into three groups: carboxylic acids and salts, amino polycarboxylates, and phosphonic acid. The distribution coefficients of both Pu^4 +  and UO²⁺ ₂using a number of different back-extractants were measured and compared. The results obtained suggest that the only practical back-extractants are carboxylic acids. Among the carboxylic acids tested, oxalic acid is suitable when the UO²⁺ ₂ concentration in the organic phase is less than 2 g/L. For UO²⁺ ₂concentrations between 2 and 10 g/L, oxalic acid-nitric acid mixtures may be used. For UO²⁺ ₂concentrations greater than 10 g/L, the only practical back-extractant is glycolic acid. The results obtained here may be used to further develop a new process for separation of Pu^4 +  and UO²⁺ ₂ from TBP-TRPO/kerosene mixture.     

Study on SO2 Poisoning Mechanism of CO Catalytic Oxidation Reaction on Copper–Cerium Catalyst

CuO–CeO₂ (Cu–Ce) catalyst with a CuO/CeO₂ mass ratio of 1 prepared by a sol–gel method is used in the CO catalytic oxidation reaction in the actual industrial sulfur-containing atmosphere. At a reaction temperature of 200 °C, the catalyst exhibits quite different stability under sulfur-containing and sulfur-free conditions. When 30 ppm SO₂ was added to the feed gas, the Cu–Ce catalyst had an initial CO conversion rate of 100%, gradually decreasing after 26 h, and this catalyst completely deactivated at about 50 h. However, the CO conversion rate of the catalyst under sulfur-free conditions could be nearly maintained at 100% within the measured time range (60 h). The results of IR, Raman, and XPS characterizations proved that the accumulation of cerium sulfate on the Cu–Ce catalyst would cover the active sites of the catalyst, eventually leading to the complete deactivation of the catalyst, which provides favorable evidence for the actual industrial anti-sulfur application.

Graphical Abstract

     

激光熔覆原位合成TiC/Fe的研究

利用激光熔覆技术合成TiC/Fe复合熔覆层,通过改变激光功率P和扫描速度v,获得不同激光参数下的试样。对不同试样进行SEM、EDS,分析其熔覆层的微观形貌和元素组成;进行XRD,确定熔覆层的组织成分;同时对每个试样进行耐磨性的测试。分析表明,当P=3.7 kW、v=3 mm/s时,熔覆层的效果最佳。     

保护气体的测试及分析

通过对气保、混合室、锡槽有关部位H2、N2纯度的检测,分析锡槽“冒烟”的原因。     

Al2O3/TiB2/Al复合材料的微观结构和高温力学性能

以细雾化铝粉和TiB₂颗粒为原料,通过粉末冶金和热轧制制备微米TiB₂和纳米Al₂O₃颗粒增强铝基复合材料。室温时,由于TiB₂和Al₂O₃的综合强化作用,Al₂O₃/TiB₂/Al复合材料的屈服强度和抗拉强度分别为258.7 MPa和279.3 MPa,测试温度升至350℃时,TiB₂颗粒的增强效果显著减弱,原位纳米Al₂O₃颗粒与位错的交互作用使得复合材料的屈服强度和抗拉强度达到98.2MPa和122.5 MPa。经350℃退火1000 h后,由于纳米Al₂O₃对晶界的钉扎作用抑制晶粒长大,强度和硬度未发生显著的降低。     

硫铝酸盐水泥抗酸侵蚀性能与机理研究

本文研究了硫铝酸盐水泥(CSA)在盐酸和硫酸环境下的力学性能演化规律,并探究了其抗酸侵蚀机理。分别测试了水和酸溶液养护的CSA胶砂试件的抗折强度,计算了CSA的抗酸侵蚀系数。采用XRD、TGA、CT和SEM分析了酸侵蚀导致的产物种类和数量变化,表征了微观结构演化过程。结果表明:与普通硅酸盐水泥(OPC)相比,CSA在盐酸和硫酸中抗折强度损失率更低,具有更好的抗盐酸和硫酸侵蚀能力;CSA主要水化产物(钙矾石)比OPC主要水化产物(氢氧化钙和硅酸钙凝胶)更难与酸反应,因此抗酸侵蚀能力更强。盐酸与硫酸对CSA的侵蚀机制略有不同,盐酸对CSA的侵蚀过程实质上为氢离子对CSA水化产物钙矾石的酸解,硫酸对CSA的侵蚀则是氢离子和硫酸根离子的共同作用。     

MRP II系统中基于对象关系方法的BOM管理的设计与实现

BOM是MRPⅡ系统中核心基础数据之一,是企业的信息纽带。文章从系统实现出发,在设计时用面向对象的方法建立一个面向对象的BOM模型,并在关系数据库中实现这个面向对象的模型,从而达到了用面向对象的方法来描述和建立BOM,采用成熟的关系数据库方法和相应的系统开发工具来实现对BOM数据的存储和管理的目的。