螺旋面数控加工刀具运动轨迹计算方法研究

在数控机床上加工螺旋面多采用平面啮合理论,但实际在工件表面的切削轨迹为空间曲线,针对平面编程方法存在不可消除的理论误差,对截面包络法数控加工螺旋面时刀触点和刀具运动轨迹进行研究,提出一种新的计算刀触点"最小有向距离算法"的理论并进行论证.     

不同条件热处理后Ti-15-3钛合金的再结晶织构

利用三维取向分布函数(ODF)并结合光学显微镜分析了经不同热处理后Ti-15-3钛合金的再结晶织构和显微组织。结果表明:对该合金固溶冷轧板在固溶温度下进行再结晶退火,当在空气炉中加热时,再结晶过程中形成γ纤维织构,并且随着晶粒的长大,γ纤维织构更加明显,此外亦形成了{114}纤维织构;在加热速率较快的盐浴炉中加热时,再结晶进程加快,γ纤维织构形成于再结晶晶粒的正常长大过程中;在空气炉中分级加热再结晶后,形成以高斯组分为主的散乱强织构。     

机械合金化3Y_2O_3-5Al_2O_3粉末的研究

研究了转速,球磨时间等球磨工艺对3Y2O3-5Al2O3机械合金化过程的影响。结果表明:在较低的转速下(250r/min),提供的球磨能量很低,只会细化粉体颗粒;提高转速(400r/min),会促使Y2O3发生晶型转变,由稳定的立方晶转变成非稳态的单斜晶;继续提高转速(500r/min),还会使混合粉体发生合成反应,生成YAlO3(YAP)。在转速为500r/min,球料比为20∶1的球磨条件下,3Y2O3-5Al2O3粉体发生固相反应的过程可分为两个阶段:第一阶段,Al2O3颗粒晶格畸变,快速细化;同时,高能球磨促使Y2O3发生了晶型转变。第二阶段,Y2O3晶型转变基本完成,并呈无定形化,Y2O3和Al2O3发生合成反应,生成YAlO3(YAP)。但在球磨条件下,难以合成Y3Al5O12(YAG)、Y4Al2O9(YAM)。     

接触探测系统CMM验收检测和复检检测标准的探讨

在分析ISO/CD103605:2004以及GB/T16857.5(送审稿)的基础上,对具有接触探测系统CMM验收检测和复检检测标准中的术语和定义、计量特性要求、验收检测和复检检测、应用等若干问题进行了探讨,并提出了具体修改建议。     

天然气分输减压阀流场模拟及低温应力场计算

利用有限元分析软件ANSYS,模拟实际工况载荷,对天然气分输站减压阀进行了天然气流场、阀体有限元静力及热应力分析。依据分析结果,得出阀内流场及热应力分布规律,找出阀体结构的薄弱部位,为工况条件下阀体的安全可靠性评估提供依据。     

植物生长调节剂2-(2,4-二氯苯氧基)三乙胺的合成新方法

以2,4 二氯苯酚为原料,采用相转移催化剂,经过醚化、胺化反应合成了2 (2,4 二氯苯氧基)三乙胺,总收率大于80%。研究了反应物的摩尔配比、反应时间及反应温度对2,4 二氯苯酚和二溴乙烷的醚化反应的影响,优惠工艺条件为:2,4 二氯苯酚与1,2 二溴乙烷配比为1∶30(mol/mol),反应温度80℃、反应时间10h。通过红外光谱、核磁共振氢谱和元素分析确定了目标化合物的结构。     

3-十二烷氧基-2-羟丙基三甲基氯化铵水溶液与烷烃的动态界面张力

用旋转滴法测定了3-十二烷氧基-2-羟丙基三甲基氯化铵（R12TAC）水溶液与系列烷烃的动态界面张力（DIFT），考察了浓度、温度和烷烃链长对DIFT的影响，并详细表征了DIFT随时间的变化过程。根据修正的Word-Tordai方程计算了DIFT的有关参数。结果表明：R12TAC浓度越大，DIFT曲线越低，DIFT下降越快，达平衡值的时间越短；随R12TAC浓度的增大，表观扩散系数Da从2．02×10^-10m^-2·s^-1减小到0．14×10^10m^-2·s^-1，吸附势垒Ea从2．60kJ·mol^-1增大到9．32kJ·mol^-1；温度升高，DIFT降低，表观扩散系数Da升高，而吸附势垒降低；固定一种表面活性剂溶液，测定R12TAC／系列烷烃溶液的动态界面张力，发现R12TAC／正己烷体系的DIFT最低，这与表面活性剂在水和油中的溶船度有关。     

Genome-Wide Identification and Expression Analysis of the 14-3-3 Gene Family in Mango (Mangifera indica L.)

Members of the Mi14-3-3 gene family interact with target proteins that are widely involved in plant hormone signal transduction and physiology-related metabolism and play important roles in plant growth, development and stress responses. In this study, 14-3-3s family members are identified by the bioinformatic analysis of the mango (Mangifera indica L.) genome. The gene structures, chromosomal distributions, genetic evolution, and expression patterns of these genes and the physical and chemical properties and conserved motifs of their proteins are analysed systematically. The results identified 16 members of the 14-3-3 genes family in the mango genome. The members were not evenly distributed across the chromosomes, and the gene structure analysis showed that the gene sequence length and intron number varied greatly among the different members. Protein sequence analysis showed that the Mi14-3-3 proteins had similar physical and chemical properties and secondary and tertiary structures, and protein subcellular localization showed that the Mi14-3-3 family proteins were localized to the nucleus. The sequence analysis of the Mi14-3-3s showed that all Mi14-3-3 proteins contain a typical conserved PFAM00244 domain, and promoter sequence analysis showed that the Mi14-3-3 promoters contain multiple hormone-, stress-, and light-responsive cis-regulatory elements. Expression analysis showed that the 14-3-3 genes were expressed in all tissues of mango, but that their expression patterns were different. Drought, salt and low temperature stresses affected the expression levels of 14-3-3 genes, and different 14-3-3 genes had different responses to these stresses. This study provides a reference for further studies on the function and regulation of Mi14-3-3 family members.     

HSn70-1船用冷凝管腐蚀穿孔失效分析

某船用HSn70-1冷凝管使用过程中出现腐蚀穿孔。通过化学成分、金相组织和能谱分析以及扫描电镜等方法对失效样品进行了分析。结果表明,介质中的Cl~-引起管内壁局部点蚀,加上冲刷腐蚀、脱锌腐蚀、晶间腐蚀的交互作用,引起腐蚀加速,最终导致穿孔。提出了预防或延缓腐蚀穿孔的措施。     

An Organogermanium Compound Enhances the Initial Reaction Rate of Alkaline Isomerization of an Aldose into a Ketose through Enediol Complex Formation

We previously demonstrated that the organogermanium compound 3-(trihydroxygermyl)propanoic acid (THGP) enhances the enzymatic and alkaline isomerization of an aldose to a ketose through cis-diol complex formation by multiple mechanisms. Its higher affinity for the ketose than the aldose protects the ketose complex from alkaline decomposition. Furthermore, it has been reported that the aldose-ketose alkaline isomerization pathway includes 1,2-enediol. Therefore, we speculated that the complex-forming ability of THGP could also be applied to enediol, a transient intermediate of alkaline isomerization. To test this prediction, we analyzed the initial rates of glucose or lactose isomerization in a region where there was no substantial difference in pH with and without THGP addition. The results showed that THGP enhanced the rate of fructose or lactulose formation per unit time by approximately 2-fold compared to the control. This finding indicated that THGP could form a complex with the transition state of aldose-ketose alkaline isomerization.