Dynamic investigation of laminated composite beams with shear and rotary inertia effect subjected to the moving oscillators using FEM

An algorithm based on the finite element method (FEM) has been developed to study the dynamic response of composite laminated beams subjected to the moving oscillator. The first order shear deformation theory (FSDT) is assumed for the beam model. The algorithm accounts for the complete dynamic interaction between the components of system. The proposed method can also be applied to the general moving mass and the simplified moving force problems. After deriving the governing equations of motion of beam and oscillator, the corresponding equations of motion are integrated by applying the Newmark’s time integration procedures to obtain the system responses in each time step. The numerical results of free vibration and moving force problems analysis of isotropic and composite laminated beams are presented and, whenever possible, compared to the available analytical solution and other numerical results in order to demonstrate the accuracy of the present method. In addition, parametric analysis is carried out over a wide range of velocities and mass, frequency and damping ratios of system components.     

小方坯连铸机结晶器振动装置设计及特点

小方坯连铸机结晶器振动装置采用半板簧结构,双偏心驱动,内弧侧布置,设有弹簧过载保护装置,集合了仿弧精度高、结构简单、重量轻诸多优点。通过ADAMS机械系统动力学仿真分析软件创建振动系统虚拟样机模型,用其求解器对系统进行运动学分析,然后进行设计优化,获得高仿弧精度的结晶器振动装置的结构位置关系。最后对振动装置进行动态静力学分析,计算驱动力矩,为电机的选取和强度校核提供了依据。     

变参数法优化方坯连铸机结晶器振动参数

研究如何用变参数法优化结晶器振动装置的振动参数,使振动装置在满足工艺要求的条件下,稳定性和可靠性均能得到有效的提高。     

Reliability analysis of MOS varactor in CMOS LC VCO

The paper investigates the reliability of MOS varactor tuned voltage-controlled oscillators (VCO). Due to the stress induced threshold voltage shift of the MOS varactor, the resonant tank degrades and the center frequency and phase noise of VCO deviate. The behavior is modeled and an adaptive body biasing scheme is proposed to make VCO resilient to reliability. In the mean time it does not degrade the VCO performance. An LC VCO at 24 GHz carrier frequency with adaptive body biasing is compared with VCO without such biasing design in PTM 65 nm technology. The ADS simulation results show that the biasing design helps improve the robustness of the VCO in resonant frequency. The design reduces the frequency sensitivity of VCO by 20% when subjected to threshold voltage degradation.     

Resistorless dual-mode quadrature sinusoidal oscillator using a single active building block

This paper presents a new realization of resistorless mixed-mode (i.e. both voltage-mode and current-mode) quadrature sinusoidal oscillator using a new active building block (ABB) called the differential voltage current-controlled conveyor transconductance amplifier (DVCCCTA). The proposed oscillator circuit uses a single DVCCCTA, two grounded capacitors (GCs) and does not employ any external linear resistors. The tuning laws for the condition of oscillation (CO) and the frequency of oscillation (FO) are non-interactive; and controlled by separate bias currents. The circuit provides two explicit quadrature current outputs and two quadrature voltage outputs and thus can be classified as a mixed-mode quadrature oscillator. Another notable feature of the proposed circuit is that it can also be used as a biquadratic filter to realize low-pass and band-pass filtering functions simultaneously. Non-ideal analysis of the circuit is provided and PSpice simulation results have been included to verify the workability of the proposed circuit.     

Cobalt oxide nanosheet humidity sensor integrated with circuit on chip

The work studies a micro humidity sensor integrated with a seven-stage ring oscillator circuit-on-a-chip fabricated by the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and a post-process. The structure of the humidity sensor consists of interdigitated electrodes and a sensing film. The sensing film is cobalt oxide nanosheet that is prepared by a precipitation-oxidation method. The sensor, which is a capacitive type, changes in capacitance when the sensing film adsorbs or desorbs water vapor. The ring oscillator circuit is employed to convert the capacitance of the sensor into the oscillation frequency output. The post-process of the sensor includes etching the sacrificial oxide layer and coating the sensing film on the interdigitated electrodes.     

外腔式KTP光学参量振荡器的实验研究

利用脉冲氙灯抽运的Nd：YAG被动调Q激光器输出的1．06μm激光脉冲泵浦KTP光学参量振荡器,获得脉宽3ns、单脉冲能量30mJ、中心波长1568nm的信号光输出。信号光脉冲宽度（3ns）比抽运光脉冲宽度（12ns）4,得多。实验表明,随着OPO腔长的增加单脉冲输出能量减小,随着抽运光能晕的增加单脉冲输出．能晕增大,...     

基于能动分块反射镜的七路激光阵列倾斜校正与相干合成实验研究

提出了一种基于能动分块反射镜(ASM)的激光阵列相位控制新方法,用以解决激光主振荡功率放大(MOPA)器相干合成技术中的空间光束倾斜校准与输出端相位调制两大关键问题。介绍了7单元能动分块反射镜实现空间光调制的原理,并采用该器件成功验证了7路光束合成的方案。实验采用六棱反射锥进行光束合成,并采用两套控制回路分别实现了倾斜与平移校正,获得了小于25μrad和λ/10的校正精度。闭环后,获得了主瓣占总功率31.73%的高质量相干耦合激光输出。     

1030nm高重复频率纳秒脉冲全光纤放大器

采用脉冲调制的单模带尾纤输出的半导体激光器作为种子源,以掺镱光纤为增益介质,采用主振荡功率放大(MOPA)结构,实现了1030nm全光纤脉冲激光放大。脉冲重复频率在50～100kHz范围内可调,在重复频率50kHz时,实现了脉冲宽度为6.53ns,峰值功率为16.08kW的脉冲输出,相应的斜率效率为69%,输出激光的中心波长在1029.49nm。实验还研究了不同重复频率下输出激光脉冲的时域特性。该激光器的输出波长在激光雷达探测器的光谱响应范围内,可作为激光雷达发射光源。     

低功率抽运光纤参量振荡器的时钟提取抖动性能

采用两次光调制技术将非归零(NRZ)码数据转换成归零(RZ)码光信号后,利用光纤参量振荡器(FOPO)结构实现了较低光功率抽运下的参量波长转换和时钟提取功能。实验表明,对于波长转换间隔为1.6nm的10Gbit/s时钟提取,优化的输入抽运光功率范围是8～14dBm;当输入信号的幅度抖动和相位抖动分别大于2.28mV和3.5ps时,该时钟提取系统可实现抖动抑制功能,其输入/输出抖动转移曲线斜率约为0.29和0.16。