基于FBG反射谱特征的铁路道岔损伤识别试验研究

针对道岔结构性能及安全状态对列车(尤其高速列车)行车安全与运行质量的重要性,提出基于光纤布拉格光栅(FBG)传感技术,利用FBG传感器反射谱特征对铁路道岔钢轨结构进行损伤(裂纹)识别。在带裂纹的道岔钢轨上安装FBG传感器进行静、动态加载室内实验。通过分析FBG传感器反射谱形状精细变化,实现对裂纹的识别。实验结果表明,该基于FBG反射谱特征的损伤识别方法可有效识别铁路道岔钢轨裂纹。中央高校基本科研业务费专项资金资助(2013QNA4023);国家自然科学基金(51108392,U1234201

Design of Ultra-wideband Printed Rectangular Monopole Antenna

针对超宽带通信应用,研究影响印制单极天线阻抗带宽的主要因素,设计基于微带馈电的小型化印制矩形单极天线。按照等效性原理,采用黄金分割比设计矩形振子体;通过接地面上端引入渐变梯形或凹形结构,同时调整馈入端接地面间隙,可实现印制矩形单极天线的超宽带特性。对具有渐变梯形或凹形接地面结构的微带馈电矩形印制单极天线结构进行优化,仿真结果表明,前者的阻抗带宽为2.96~17.94gHz,后者的阻抗带宽为2.9~13.3gHz,而两者的辐射方向基本保持不变。实测结果与仿真结果基本一致,达到了超宽带通信应用的要求。To achieve ultra-wideband(UWB)radio applications,the microstrip-fed printed rectangular monopole antenna is analyzed and devised.Using golden section ratio the rectangular monopole is of layout based on equivalent principle.To maximize the impedance bandwidth,it is necessary introducing the taper or concave ground plane and feed gap of microstrip line.The simulated results of the optimized-size antennas show that the impedance bandwidth defined by return loss less than-10dB is from 2.96GHz to 17.94GHz with a ratio of about 6.06∶1 for taper ground antenna and from 2.9GHz to 13.3GHz with a ratio of about 4.59∶1 for concave ground antenna.At the same time a nearly omnidirectional radiation pattern is exhibited.These results are confirmed by the experimental test and these compact size antennas are suitable for various wideband applications.福建省科技计划重点资助项目(2007H0036

1976 Vol. 24 Number 11

https://engagedscholarship.csuohio.edu/lawpublications_gavel1970s/1100/thumbnail.jp

Thermal pretreatment and subsequent pyrolysis of lignite

热解是一种从煤中直接获取低碳燃料及高值化学品的温和转化工艺。现有热解技术存在焦油产品收率低且焦油中的重质沥青质组分含量高的缺点，给装置的连续运行及油品的深加工带来问题，因而在工业上还没有得到广泛应用。对热解反应前的煤进行预处理，能够改善煤中结构、改变其元素配比，进而可能调控热解油品收率及品质。其中热预处理能够利用常见低品位热源，在低于热解温度条件下的不同气氛中，对煤样的结构及组成进行一定的改变，使其热解行为发生变化。针对中国储量多、含水高的褐煤，热预处理可同时实现其干燥脱水，还可充分利用热烟气及过热水蒸汽等低品位热源，因而具有极高的实际工业可应用性。 本论文采用固定床反应器研究了不同气氛、温度条件下热预处理内蒙胜利褐煤对煤元素组成和官能团结构的改变，表明：随着预处理温度的升高，煤中气体释放量增加，释出气体的主要成分为CO2。含O2气氛下的预处理过程中煤释放的气体量比惰性气氛下要高。与原煤相比，热预处理后煤中羟基的红外吸收强度减弱，芳香氢与脂肪氢的红外吸收强度比减少，脂肪氢的相对含量增加，表明煤中的氢源分布情况发生了改变。原煤的表面吸附能力较强，经过热预处理后，受干燥及煤中部分挥发分逸出的影响，中孔数量减少而微孔数量相对增多。预处理后的煤在同一反应器中直接升温至600 ℃发生原位热解。与未经处理的煤热解相比，N2、N2＋O2、CO2气氛下热预处理后热解水收率下降，热解气收率增加，热解气中CO2含量增高，从而导致热值下降。过热水蒸汽热预处理后，焦油质量收率提高约3～4个百分点。热解焦油组成的变化与预处理气氛和温度密切相关，过热水蒸汽在200 ℃时的预处理容易使得焦油中轻质组分的含量（沸点低于360 ℃的馏分）比原煤热解焦油提高了约27个百分点。水蒸汽与模拟烟气的混合气氛下在200 ℃及250 ℃预处理后，其热解焦油中轻油和酚油含量分别提高约60和42个百分点

Equivalent Linearly Rotating Plates Constructed by Variable Plates

利用四元数理论分析了可变延迟波片,并依此由可变延迟波片组合构造了等效可转线性半波片和四分之一波片.提出由可变延迟波片按可转波片控制算法设计偏振控制器,以避免可变延迟波片偏振控制器所需的复位重置过程.仿真结果显示,按此构想得到的四波片控制器,能把任意偏振态转换为固定线偏振输出,其光强波动小于1%,相移范围不超过2π,控制过程不需要附加复位操作,其相移变化平缓.Variable retardation plates(VRP) were analyzed by quaternion theory and equivalent rotatable quarter-wave plates and rotatable half-wave plates were constructed from sequences of adjustable linear retarders with fixed retardation axes.To avoid reset,a polarization controller(PC) based on adjustable linear retarders using polarization controlling algorithm for rotatable plates was proposed and demonstrated.Simulation results show that the 4-plate polarization controller can transform any varying general input state of polarization(SOP) into an arbitrary linear output state of polarization,and the fluctuation of output light intensity is less than 1% while the rang of retardation is confined into 2π.This transformation is continuous,and reset-free and the phase shifts are smooth.厦门大学引进入才科研启动基金(E33011)资

Optical Frequency Multiplication of Phase Modulator and Birefringent Fiber

为实现毫米波信号的光学倍频法产生,利用相位调制器和光纤梳状滤波器,构建了光学倍频系统.其中光纤梳状滤波器由起偏器、双折射光纤和检偏器组成.理论分析表明,在该倍频系统中,通过对梳状滤波器双折射延迟量的选择,可有效地抑制非期望的奇次(偶次)谐波成分;通过对调相指数的优化,可进一步提高期望谐波分量的比例.仿真结果说明,利用该系统可有效地产生60 gHz的毫米波信号,并实现2.5 gbPS基带信号的传输.理论分析和仿真验证也表明,基于相位调制的光学倍频系统属于谐波倍频,而非扫频倍频.To generate millimeter-wave signal using optical method,a optical frequency multiplication(ofM) system was constructed with a phase modulator and a fiber periodic filter.The periodic filter was made of two polarizers and a segment of birefringent fiber.The theoretical analysis shows that in this system the unexpected odd/even harmonic components can be suppressed effectively by adjusting the birefrigent fiber delay.Furthermore,the desired electrical harmonics can be given prominence to the others by optimizing the phase modulation index.The simulation results demonstrate that the 60 GHz millimeter-wave signal can be effectively generated,and 2.5 Gbps NRZ signals can be correctly transmitted in this ofM system.The theoretical and simulation results also indicte that the ofM system based on the sinusoidal-signal phase modulation should be analyzed using the harmonious optical sidebands,instead of the sweeping frequency theory.国家自然科学基金(No.61077031)资

Implementation of Low-Frequency Periodic Vibration Sensor Based on Frequency-Swept Fiber Laser

针对低频周期振动光纤传感的应用,通过光纤光栅的周期调谐,构建了环形腔结构的低频周期扫频光纤激光器。以光纤光栅珐布里-珀罗腔为梳状滤波器,利用光学倍频法设计了光源扫频周期的测量系统。实验产生了7.2Hz的周期扫频激光输出,通过测量系统得到了14.39Hz的倍频电信号。实验结果表明该系统可有效地模拟低频光源周期扫频,并进行扫频频率的准确测量。To simulate the periodic and weak vibration in the fiber sensor application,a loop-cavity fiber laser of the periodic frequency sweeping is constructed by tuning the fiber Bragg grating(FBG).To measure the sweeping frequency,the optical frequency multiplication is applied with the help of fiber Bragg grating Fabry-Perot cavity.This fiber laser has experimentally radiated a 7.2 Hz frequency-swept laser and 14.39 Hz electric signal is obtained by the frequency multiplication method.The experimental results show that this system can efficiently simulate the periodic frequency-swept light wave and exactly measure the sweeping frequency.国家自然基金(61077031)资助课

热预处理影响褐煤热解行为研究

采用固定床反应器研究了不同气氛热预处理对内蒙胜利褐煤结构的改变,及其对后续热解行为的影响。结果表明,与原煤相比,热预处理后煤中羟基含量和芳香氢与脂肪氢的比减少,脂肪氢的相对含量增加。与未经处理的煤热解相比,N2、N2＋O2、CO2气氛下热预处理后热解水收率下降,热解气收率增加,热解气中CO2含量增高,导致高位热值下降。过热水蒸气热预处理后,焦油质量收率提高3～4个百分点。热解焦油组成的变化与预处理气氛、温度密切相关,过热水蒸气200℃下预处理使得焦油中轻质组分的含量（沸点低于360℃的馏分）比原煤焦油提高了约27个百分点;水蒸气和模拟烟气混合气氛下在200℃及250℃预处理后,其热解焦油中轻油和酚油含量分别提高约60和42个百分点

热预处理影响褐煤热解行为研究

采用固定床反应器研究了不同气氛热预处理对内蒙胜利褐煤结构的改变,及其对后续热解行为的影响。结果表明,与原煤相比,热预处理后煤中羟基含量和芳香氢与脂肪氢的比减少,脂肪氢的相对含量增加。与未经处理的煤热解相比,N2、N2＋O2、CO2气氛下热预处理后热解水收率下降,热解气收率增加,热解气中CO2含量增高,导致高位热值下降。过热水蒸气热预处理后,焦油质量收率提高3～4个百分点。热解焦油组成的变化与预处理气氛、温度密切相关,过热水蒸气200℃下预处理使得焦油中轻质组分的含量（沸点低于360℃的馏分）比原煤焦油提高了约27个百分点;水蒸气和模拟烟气混合气氛下在200℃及250℃预处理后,其热解焦油中轻油和酚油含量分别提高约60和42个百分点