Detection optimization for resonance region radar with dense multi-carrier waveform

Unlike the existing resonance region radar systems （RRRS ） that transmit the orthogonal frequency division multiplexing （OFDM）multi-carrier waveform,the dense multi-carrier （DMC）radar waveform which has a narrower frequency interval than the traditional OFDM waveform is proposed.Therefore,in the same frequency bandwidth,the DMC waveform contains more sub-carriers and provides more frequency diversity.Additionally,to further improve detection performance,a novel optimal weight accumulation target detection （OWATD）method is proposed,where the echo electromagnetic waves at different frequencies are accumulated with the optimal weight coefficients.Then,with the signal-to-noise ratio （SNR）of echo waveform approaching infinity,the asymptotic detection performance is analyzed, and the condition that the OWATD method with the DMC outperforms the matched filter with the OFDM is presented.Simulation results show that the DMC outperforms the OFDM in the target detection performance,and the OWATD method can further improve the detection performance of the traditional methods with both the OFDM and DMC radar waveform.

An Open-Loop Test of a Resonator Fiber Optic Gyro

The resonator fiber optic gyro （R-FOG） ,which utilizes a resonance frequency change due to the Sagnac effect,is a promising candidate for the next generation inertial rotation sensor. In this study, an open-loop R-FOG is set up using phase modulation spectroscopy. First,the demodulation curve is obtained using a lock-in amplifier. From the demodulation signal,a gyro dynamic range of ± 4.2rad/s is obtained. Then,using different phase modulation frequencies,the open-loop gyro output signal is measured when the gyro is rotated clockwise or counterclockwise. The bias drift as a function of time is also measured. The fluctuation of the output over 5s is about 0.02rad/s. The drift can be reduced by taking countermeasures against system noise.

配电网对地泄漏电阻回归测量技术研究

为满足不同条件下对配电网对地泄漏电阻的测量,文章以某配电网为例,开展了配电网对地参数测量中的振谐检测、配电网对地泄漏电阻测量中的影响因素补偿、配电网馈线零序电流与对地泄漏电阻的回归计算的研究。实验结果表明:文章设计的测量方法在实际应用中的效果良好,该方法可以在不同脱谐度、不同接地档位下,实现泄漏电阻值的精准测量,保证测量值与实测值的相对偏差在±5%。

Ice Detecting and Measuring Technologies on Power Lines

Ice detecting and measuring technologies used and developed for high voltage transmission lines are introduced in this paper. The Icing Rate Meter developed by Hydro-Quebec, working with the magnetostriction principle and regulated by an electronic control system is analyzed and the resonant piezoelectric transducers operated by a microprocessor-controlled electronic circuitry is also analyzed in great detail. It shows that the Icing Rate Meter (IRM) developed by Hydro-Quebec can record the occur- rence and duration of icing events, but has two limitations: information on changes in the rate of icing within each hour is lost and the amount of time consumed during heating cycles is not taken into account. A resonant piezoelectric ice detector can automatically and distinctly sense ice and water films up to 0.5 mm thick. It is a smart ice detection system, which might be used widely.

Detection of Blade Mistuning in a Low Pressure Turbine Rotor Resulting from Manufacturing Tolerances and Differences in Blade Mounting

For a serious prediction of vibration characteristics of any structure, a detailed knowledge of the modal characteristic is essential. This is especially important for bladed turbine rotors. Mistuning of the blading of a turbine rotor can appear due to manufacturing tolerances or because of the blading process itself due to unequal mounting of the blades into the disk. This paper investigates the mistuning of the individual blades of a low pressure turbine with respect to the effects mentioned above. Two different rotors with different aerodynamic design of the blades were investigated. The blades were mounted to the disk with a so-called hammer head root which is especially prone to mounting irregularities. For detailed investigations, the rotor was excited with a shaker system to detect the forced response behavior of the individual blades. The measurements were done with a laser vibrometer system. As the excitation of rotor structure was held constant during measurement, it was possible to detect the line of nodes and mode shapes as well. It could be shown that the assembly process has an influence on the mistuning. The data were analyzed and compared with numerical results. For this, different contact models and boundary conditions were used. The above described characterization of modal behavior of the rotor is the basis for the upcoming aeroelastic investigations and especially for the blade vibration measurements of the rotor, turning with design and off-design speeds.

850 nm Implant-confined VCSEL Temperature Characteristics

The temperature characteristics of VCSEL using proton implantation are described,compared with its edge-emitting counterpart.Implant-confined VCSEL operation has been realized up to 120 ℃.These records of high operating temperature are caused by high characteristic temperature. The relevant physical mechanisms including their dependence on temperature and carrier density are considered. The temperature sensitivity of the threshold current is not strongly increasing with higher temperature.

Opto-Chemical Ring Resonator Sensor Based on Morphology Dependent Resonances for Detecting Gas Odorant

A novel Opto-Chemical Ring Resonator （OCRR） has been presented for detecting gas odorant. The sensor is designed based on Morphology Dependent Resonances （MDR） which follows Maxwell＇s electromagnetic equations. In this paper, we have presented a novel technique to integrate chemical science and optical technology by using OCRR. Optical resonances of electromagnetic wave propagations in dielectric micro-ring resonator have been developed based on asymptotic approach. Parametric studies based on developed asymptotic expression have been presented to determine the resonance frequency at particular chemical composition. Finite element simulation is used to predict the performance of the sensor and found encouraging results for odorant sensing. Parametric studies show that present study will help to develop novel OCRR sensors tbr micro/nano technology and biomedical applications.

All-optical scheme for detecting the possible Majorana signature based on QD and nanomechanical resonator systems

Majorana fermions(MFs) are exotic particles that are their own anti-particles. Currently, the search for MFs occurring as quasiparticle excitations in condensed matter systems has attracted widespread interest, because of their importance in fundamental physics and potential applications in topological quantum computation based on solid-state devices. Motivated by recent experimental progress towards the detection and manipulation of MFs in hybrid semiconductor/superconductor heterostructures, in this review, we present a novel proposal to probe MFs in all-optical domain. We introduce a single quantum dot(QD), a hybrid quantum dot-nanomechanical resonators(QD-NR) system, and a carbon nanotube(CNT) resonator implanted in a single electron spin system with optical pump-probe technology to detect MFs, respectively. With this scheme, a possible Majorana signature is investigated via the probe absorption spectrum and nonlinear optical Kerr effect, and the coupling strength between MFs and the QD or the single electron spin is also determined. In the hybrid QD-NR system, vibration of the NR will enhance the nonlinear optical effect, which makes the MFs more sensitive for detection. In the CNT resonator with a single electron, the single electron spin can be considered as a sensitive probe, and the CNT resonator behaved as a phonon cavity is robust for detecting of MFs. This optical scheme will provide another method for the detection MFs and will open the door for new applications ranging from robust manipulation of MFs to quantum information processing based on MFs.