一种精确测量ASTM标准圆形拉伸试样锥度的方法

介绍了ASTM标准中圆形拉伸试样主要部位的尺寸与要求。采用国产万能工具显微镜-投影法对试样在平行长度部位的锥度进行了测量。该方法简便易行,结果准确可靠,满足了标准要求,同时发挥了老设备的作用,保证了试样的加工精度。     

标量衍射理论的非傍轴修正

当光束具有较大的发散角或光束束腰可与波长相比拟时,傍轴近似不再成立.用微扰级数法处理非傍轴光束的传播问题,数值计算发现,对受硬边光阑限制的光束,由于高频分量的贡献,当传输距离较大时,高阶级数解的修正效果不好,甚至失效,级数解的有效范围将受到很大限制.在标量衍射理论角谱表示的基础上,以平面波圆孔衍射为例,给出了衍射场的非傍轴修正解,得到的非傍轴修正解避免了级数解本身在数学上的发散性问题,并在一定条件下,可过渡到级数解,并且指出在近场或非傍轴区对傍轴解进行高阶修正的必要性和有效性.     

圆锯片振动频率的控制方法

中心夹持高速旋转的圆锯片切削工件时,保持良好的切削稳定性是非常重要的.目前提高锯片切削稳定性的方法有研究新的锯片材料、改善材料性能、改变锯片的结构和几何参数、改变齿形和对锯片进行适张度处理等,对圆锯片采用胀孔适张度处理,在锯片上均布加工一些孔,然后在孔中压入圆锥塞,使之在锯片内产生残余应力场,残余应力场的存在提高了锯片的固有频率,减少锯片的横向振动,从而增加了锯片切削的稳定性.     

基于NURBS曲线的逼近研究

介绍了直线逼近和圆弧逼近2种NURBS曲线逼近算法,并在两者的基础上,提出对NURBS曲线进行混和逼近的新算法,最后,通过实例验证了该算法的正确性与可行性。     

Aeroelastic stability of heated functionally graded cylindrical shells containing fluid

The article is concerned with the analysis of panel flutter of heated circular clamped cylindrical shells made of functionally graded (FG) material, which are subject to a simultaneous action of the external supersonic gas flow and the internal flow of ideal compressible fluid. The effective properties of the material change throughout the thickness of the shell according to a power law and depend on temperature. The aerodynamic pressure is calculated based on the quasi-static aerodynamic theory. The behavior of the fluid is described in the framework of the potential theory. A mathematical formulation of the dynamic problem for elastic structure is developed based on the classical theory of shells and the principle of virtual displacements. Based on the results of numerical simulation the influence of different consistencies of the examined FG materials, thermal load, and internal flow velocity on the boundary of aeroelastic stability is analyzed.     

Frequency tunable circularly polarized antenna with branch line coupler feed network for wireless applications

In this article, frequency tuning and circularly polarized concentric circular microstrip antenna is investigated. The proposed antenna consist of varactor diode for frequency tuning and branch line coupler (BLC) feed network to achieve the circular polarization (RHCP/LHCP). By changing the varactor diode capacitance between 12.33 pF (0 V) to 1.30 pF (15 V) attain the frequency tuning (2.34‐2.68 GHz). The right hand circular polarization (RHCP) and left hand circular polarizations (LHCP) are realized in the antenna through BLC feed network output ports. The impedance bandwidth (2.05‐3.13 GHz) of BLC feed network is well‐matched with the circular microstrip antenna frequency tunable bandwidth. The proposed antenna is fabricated, and simulated results are verified using the mathematical modeling and experimental verification.     

Critical Roles of Circular RNA in Tumor Metastasis via Acting as a Sponge of miRNA/isomiR

Circular RNAs (circRNAs), a class of new endogenous non-coding RNAs (ncRNAs), are closely related to the carcinogenic process and play a critical role in tumor metastasis. CircRNAs can lay the foundation for tumor metastasis via promoting tumor angiogenesis, make tumor cells gain the ability of migration and invasion by regulating epithelial-mesenchymal transition (EMT), interact with immune cells, cytokines, chemokines, and other non-cellular components in the tumor microenvironment, damage the normal immune function or escape the immunosuppressive network, and further promote cell survival and metastasis. Herein, based on the characteristics and biological functions of circRNA, we elaborated on the effect of circRNA via circRNA-associated competing endogenous RNA (ceRNA) network by acting as miRNA/isomiR sponges on tumor angiogenesis, cancer cell migration and invasion, and interaction with the tumor microenvironment (TME), then explored the potential interactions across different RNAs, and finally discussed the potential clinical value and application as a promising biomarker. These results provide a theoretical basis for the further application of metastasis-related circRNAs in cancer treatment. In summary, we briefly summarize the diverse roles of a circRNA-associated ceRNA network in cancer metastasis and the potential clinical application, especially the interaction of circRNA and miRNA/isomiR, which may complicate the RNA regulatory network and which will contribute to a novel insight into circRNA in the future.     

马钢一铁3号鼓风环冷机密封装置的改造

针对马钢一铁总厂3号鼓风环冷机存在的密封不严的问题,分析了传统密封装置在结构设计和制造上存在的缺陷。在此基础上,设计开发了一种新型密封装置,根除了传统密封装置的诸多弊病。该装置在马钢一铁总厂3号鼓风环冷机上使用后,效果良好。     

透镜球差对拉盖尔-高斯涡旋光束聚焦特性的影响及改善方法

涡旋光场调控对涡旋光在激光通信、生物操控等领域的应用研究具有重要意义。为了揭示透镜球差对拉盖尔-高斯(Laguerre-Gaussian,LG)涡旋光束传输特性的影响,本文基于菲涅尔衍射理论,模拟研究了不同透镜球差系数下的LG光束聚焦场的强度、相位以及螺旋谱分布。结果表明:光学系统初级球差系数的增大恶化了LG光束聚焦场的强度分布和螺旋相位,弥散了轨道角动量(orbital angular momentum,OAM) 。由此,本文提出了一种光阑补偿方案,通过在透镜前添加大小合适的圆孔光阑,以消除透镜像差。光阑补偿后的LG光束聚焦场由星芒状空心分布恢复为空心圆环分布,OAM态保持单一稳定。本研究工作为改善透镜像差对涡旋光的传输影响提供了解决方案。     

非线性弹性地基上圆形薄板主参数共振-主共振研究

研究非线性地基上圆形薄板受简谐激励的非线性振动问题。按照弹性力学理论建立非线性地基上圆形薄板受简谐激励的动力学方程。利用Galerkin方法将其转化为非线性振动方程,它是达芬-马休型方程。应用非线性振动的多尺度法求得系统主参数共振-主共振条件的一次近似解,并进行数值计算。分析阻尼、地基系数、几何参数等对共振响应曲线的影响。比较了两种地基的计算结果。