摩擦力对滚珠丝杠惯容器频响特性的影响

为建立更精确的惯容器模型和完善惯容器设计理论与方法,设计丝杠旋转式滚珠丝杠惯容器,搭建惯容器试验台架,研究非线性因素对惯容器的影响。采用系统识别的方法,将时域响应试验数据转化为频域响应数据,得到惯容器的频响特性曲线,以惯容器Malcolm线性模型为试验研究的比较对象,分析无背隙情况下摩擦力对滚珠丝杠惯容器频响特性的影响。结果表明:低频下,滚珠丝杠惯容器摩擦力占据主导地位,导致惯容器相位跌落、幅值增大;随着频率和惯容系数的增大,摩擦力对惯容器的影响相对减小,惯容器实际性能与理论性能逐步接近。     

尾部扩散器对某跑车气动性能的影响

以某跑车模型为研究对象,探讨尾部小型扩散器对于车身气动性能的影响。在初始模型的基础上,进行CFD(Computational Fluid Dynamics)数值模拟计算,并对比风洞试验数据,验证仿真的可靠性。对初始模型的扩散器进行改进设计,加大扩散器的工作区域,研究其对于气动力的影响,并将改进后的扩散器与带有仿生凹坑型非光滑扰流器结合起来,通过数值模拟方法,得出压力和速度等流场参数,比较不同形式的扩散器对于气动性能的改进效果,分析气动力改善的原因。结果表明:通过对扩散器与非光滑扰流器的优化组合,能有效地提高气动负升力,减小气动阻力,达到了调谐车辆气动升力与气动阻力之间的耦合关系的目的。     

复合热稳定剂对绝缘纸协同抗老化效应的分子模拟研究

为了从微观层面探究热稳定剂的复合添加对绝缘纸协同抗热老化特性的影响机理,以双氰胺、三聚氰胺为热稳定剂研究对象,对老化过程中的热稳定剂、β-D-吡喃葡萄糖分子、水分子和小分子酸等进行了量子化学计算,利用前线轨道理论考察了不同分子之间的化学反应活性。此外,采用分子动力学模拟软件,搭建了末添加、单一添加和复合添加热稳定剂的四种纤维素含水含酸模型,从纤维素与水分子、蚁酸分子的氢键结合数、相互作用能这两个方面考察了不同改性体系的差异及抗老化性能差异的机理。结果表明:热稳定剂分子与水分子、小分子酸的化学反应活性要强于β-D-吡喃葡萄糖分子与这些物质的反应活性;两种热稳定剂分子分别与水分子、小分子酸的反应活性存在差异,复合添加可以集中二者的优势,起到协同延缓绝缘纸老化的效果;双氰胺与三聚氰胺的复合添加在降低纤维素分子对水分子、蚁酸分子的吸附能力上存在协同作用。     

Temperature‐Dependent Scaling Behavior of Dynamic Hysteresis in Pb(Zr,Ti)O3 Ceramics

The dynamic hysteresis scaling behaviors of Nb‐doped Pb(Zr_0.52Ti_0.48)O₃ ceramics have been investigated as a function of electric field amplitude (E₀) and frequency (f) at different temperatures (T). The loop area <A> of saturated loops is found to follow various power laws as <A> ∝ E₀^0.3065 at fixed f and <A> ∝ f ^0.0120 at fixed E₀. Furthermore, the linear scaling relation <A> = k₃ f^αE₀^β + b₃ is estimated under various temperatures. The exponents α (=0.01) and β (=0.10) are T‐independent, whereas the slopes k₃ and y‐intercepts b₃ are T‐dependent because the increasing temperature in the same phase range only decreases the threshold field of the reversal rather than change the dynamic reversal process.     

光固化防尘自清洁涂料的制备及其性能研究

利用实验室自制的3种可光固化季铵盐(Photo-QAS)制备具有亲水性的光固化自清洁涂料。通过扫描电子显微镜(SEM)观察暴露于空气中的涂膜,可以发现该系列涂料均具有很好的防尘效果;通过对不同污渍在涂层表面的附着及清洗研究,发现该系列涂料具有良好的自清洁效果,并且便于清洗;通过细胞培养实验,证实细胞不易在该系列涂层表面生长贴附,具有一定抗生物垢的能力。用X光电子能谱仪(XPS)表征了涂层的表面元素组成,探究了其防污原理。     

Deep Sequencing Analysis of miRNA Expression in Breast Muscle of Fast-Growing and Slow-Growing Broilers

Growth performance is an important economic trait in chicken. MicroRNAs (miRNAs) have been shown to play important roles in various biological processes, but their functions in chicken growth are not yet clear. To investigate the function of miRNAs in chicken growth, breast muscle tissues of the two-tail samples (highest and lowest body weight) from Recessive White Rock (WRR) and Xinghua Chickens (XH) were performed on high throughput small RNA deep sequencing. In this study, a total of 921 miRNAs were identified, including 733 known mature miRNAs and 188 novel miRNAs. There were 200, 279, 257 and 297 differentially expressed miRNAs in the comparisons of WRRh vs. WRRl, WRRh vs. XHh, WRRl vs. XHl, and XHh vs. XHl group, respectively. A total of 22 highly differentially expressed miRNAs (fold change > 2 or < 0.5; p-value < 0.05; q-value < 0.01), which also have abundant expression (read counts > 1000) were found in our comparisons. As far as two analyses (WRRh vs. WRRl, and XHh vs. XHl) are concerned, we found 80 common differentially expressed miRNAs, while 110 miRNAs were found in WRRh vs. XHh and WRRl vs. XHl. Furthermore, 26 common miRNAs were identified among all four comparisons. Four differentially expressed miRNAs (miR-223, miR-16, miR-205a and miR-222b-5p) were validated by quantitative real-time RT-PCR (qRT-PCR). Regulatory networks of interactions among miRNAs and their targets were constructed using integrative miRNA target-prediction and network-analysis. Growth hormone receptor (GHR) was confirmed as a target of miR-146b-3p by dual-luciferase assay and qPCR, indicating that miR-34c, miR-223, miR-146b-3p, miR-21 and miR-205a are key growth-related target genes in the network. These miRNAs are proposed as candidate miRNAs for future studies concerning miRNA-target function on regulation of chicken growth.     

海上平台射孔、压裂、测试与水力泵快速返排求产联作测试工艺技术研究与应用

在总结以往射孔、压裂、测试井施工经验的基础上,开发了适用于海上平台射孔、压裂、测试与水力泵快速返排的联作工艺,研制了与该工艺管柱配套的海上专用压裂水力射流泵,7″大套管用防砂卡器,大通径可锁定开关井全通径压控选择测试阀(LPR-N测试阀)。并在中海油某海域探井A井进行现场试验,结果表明,该工艺技术能够满足海上平台不动管柱一次完成射孔、压裂、测试与水力泵快速返排求产的施工要求,安全、可靠,具有试油周期短,作业费用低,快速、及时返排压裂残液,有效地防止压裂残液对油层造成二次污染的特点。该工艺技术的成功实施,为以后海上油田快速评价储层提供了新的技术手段。     

基于几何变形的大数据安全隐私保护方法

隐私保护已经成为大数据安全的重要研究内容之一。在分析了影响大数据安全隐私三个方面的基础上,提出了一种基于几何变形的大数据安全隐私保护方法。该方法从数据源的角度出发,使用几何变形的方法对数据进行干扰,使得数据聚类算法失效或分析得出错误的结果,从而达到大数据安全隐私保护的目的。在实际使用中,该方法效果良好。     

共形光电防撞系统光学窗口像差校正设计

为满足新一代作战直升机在高速飞行下仍保持精确打击能力,对其光电探测系统及光学窗口采用共形布局设计.根据共形光电防撞系统0.4～0.7μm/1.064μm/3.7～4.8μm多波段的使用要求以及直升机飞行马赫数0.3～0.4的条件下,设计了长径比为1、口径100 mm、厚度5 mm,材料为MgF2的椭球面作为共形光电防撞系统光学窗口面型.运用Zernike多项式分析不同波段下光学窗口引入像差与扫描视场之间的变化关系,采用将固定校正系统置于光学窗口后的设计方法,对窗口引入的像差进行校正.最终结果表明,经过两次校正后,可见光波段各Zernike像差系数P-V值小于0.6λ,激光波段小于0.4λ,红外波段小于0.1λ,像差校正效果良好,满足设计要求.