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Yan Y.,Tianjin University | An H.,Tianjin Institute of Metrological Supervision Testing | Shi T.,Tianjin University | Xia C.,Tianjin University | Xia C.,Tianjin Polytechnic University
IET Power Electronics | Year: 2013

Input voltage unbalance causes input current waveform degradation of matrix converter because of the lack of reactive component in dc link. To reduce the harmonic content of input current, dynamic input current modulation methods based on space vector modulation strategy have been presented in some works. This study proposes two improved double line voltage synthesis (DLVS) strategies for matrix converters. Both strategies apply the dynamic input current modulation methods to DLVS aiming at improving input and output waveforms at the same time. Besides, simplicity is another advantage of the methods proposed in this study. Phase detection of input current modulation vector is eliminated, which reduces the calculation time of control algorithm. Numerical simulations and experiments with a 10 kW prototype are carried out. The results are given to verify the feasibility and effectiveness of the proposed strategies. © The Institution of Engineering and Technology 2013.


Shi T.,Tianjin University | Yan Y.,Tianjin University | An H.,Tianjin Institute of Metrological Supervision Testing | Li M.,ZhongHuan TIG Company | And 2 more authors.
IEEE Transactions on Industrial Electronics | Year: 2013

This paper presents two improved double line voltage synthesis strategies for matrix converters. Both strategies redistribute the on-time intervals of the switches to reduce the output voltage error caused by the limit of minimum safe pulsewidth during commutation process. The first strategy reconstructs the modulation law according to the relationship between the input and the output voltages. The second strategy takes the current relationship into account, and the on-time intervals are calculated using the instantaneous output currents. Without increasing the commutation times and switching losses, the proposed strategies can decrease the number of pulses whose duty cycles are less than the minimum limit and improve the output voltage waveform. Moreover, the second one can also enhance the input current quality. Numerical simulations and experiments with a 10-kW prototype are carried out. The results are given to verify the feasibility and effectiveness of the proposed strategies. © 1982-2012 IEEE.


Zhu J.,Tianjin University | Guo T.,Tianjin University | Lin J.,Tianjin University | Zhang T.,Tianjin Institute of Metrological Supervision Testing | Cui P.,Tianjin University
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2014

The mode number of optoelectronic oscillators is the key parameter to establish the relationship between the oscillation frequency and loop group delay in the distance measurement method based on optoelectronic oscillators (OEO), and the mode number error can affect the accuracy directly. Due to the low frequency stability of OEO, the accuracy of mode number by measuring the oscillation frequency and inter-mode frequency spacing is not high. The influence of frequency stability on the mode number error and the change law of frequency drifts are analyzed. Then a new method to determine the mode number without changing the structure of OEO is proposed. In this method, the frequency spacing between oscillation mode and x-order-higher mode and the frequency spacing between oscillation mode and x-order-lower mode are measured separately to get the inter-mode frequency spacing, in order to compensate and reduce error induced by frequency drifts. The mode number measurement error model of this method is established. Experiments are conducted by using different methods, and the experimental results are consistent with error analysis.


Sun Y.,Tianjin University | Sun C.,Tianjin University | Yu H.,Tianjin University | Li D.,Tianjin University | Yu S.,Tianjin Institute of Metrological Supervision Testing
2015 IEEE SENSORS - Proceedings | Year: 2015

A miniaturized fiber Attenuated Total Reflection (ATR) sensor based on mid-infrared spectroscopy was proposed to overcome the drawbacks of enzyme electrode sensor for implantable continuous glucose monitoring. Two methods were proposed to improve the sensitivity of fiber ATR sensors. A single-loop structure of fiber ATR sensor was used to increase the effective optical length to enhance the sensitivity. By growing silver nanoparticles (AgNPs) on the cylindrical surface of the fiber ATR sensor with chemical silver mirror method, the sensitivity of the infrared absorption signal was further enhanced. In the experiment, the AgNPs modified fiber ATR sensor showed an intense absorption signal for glucose with enhancement factors of two to six times at different absorption wavenumbers compared with the bare fiber ATR sensors. The prediction of glucose concentration with high accuracy was achieved by using the five-variable partial least-squares model yielding a root-mean-square error of prediction as small as 4.45 mg/dL. © 2015 IEEE.


Sun C.,Tianjin University | Cao Y.,Tianjin University | Sun Y.,Tianjin University | Yu S.,Tianjin Institute of Metrological Supervision Testing | And 2 more authors.
MicroTAS 2015 - 19th International Conference on Miniaturized Systems for Chemistry and Life Sciences | Year: 2015

This paper presented a miniaturized flattened fiber ATR sensor enhanced by sliver nanoparticles (AgNPs) for implantable continuous glucose monitoring. A flattened structure was designed to increase the effective optical length in limited space to improve the sensitivity of the sensor. AgNPs were grown on the surface of both the flattened area of the fiber via chemical silver method to further improve the sensitivity by increasing the infrared absorption. The AgNPs enhanced flattened fiber ATR sensor combined with a CO2 laser showed an intense absorption signal from glucose molecules with an enhancement factor of 4.30. The root-mean-square error of 4.42 mg/dL for glucose measurement was obtained by a five-variable partial least-squares model, which could satisfy the clinical requirements. © 15CBMS-0001.


Li D.,Tianjin University | Yu S.,Tianjin Institute of Metrological Supervision Testing | Sun C.,Tianjin University | Zou C.,Tianjin University | And 2 more authors.
Biosensors and Bioelectronics | Year: 2015

An implantable U-shaped fiber ATR sensor enhanced by silver nanoparticles on cylindrical surface was presented for continuous glucose monitoring to overcome the drawbacks of traditional glucose sensing technique based on enzyme electrodes. A U-shaped structure was addressed to increase effective optical length at limited implantable space to enhance the sensitivity of fiber ATR sensor. A novel method to fabricate silver nanoparticles on cylindrical surface of U-shaped fiber ATR sensor based on chemical reduction of its silver halide material directly without any preliminary nanoparticles synthesis and following covalent bond or self-assembly was proposed. Five glucose absorption wavelengths in the mid-infrared band were employed for specific glucose monitoring. The experimental results indicate that the sensitivity and resolution of the silver-nanoparticle-enhanced U-shaped fiber-optic ATR sensor are approximately three times those of a conventional one. The high sensitivity and low-noise performance makes it promising for in vivo glucose monitoring in the future clinical applications. © 2015 Elsevier B.V.


Qiu Z.,Tianjin University | Yang X.,Tianjin University | Zheng H.,Tianjin Institute of Metrological Supervision Testing | Gao S.,Tianjin University | Fang F.,Tianjin University
Applied Optics | Year: 2015

An ultrasound-assisted micro-injection molding method is proposed to improve the rheological behavior of the polymer melt radically, and a micro-injection molding system based on a longitudinal ultrasonic vibration core is developed and employed in the micro-injection molding process of Fresnel lenses. The verification experiments show that the filling mold area of the polymer melt is increased by 6.08% to 19.12%, and the symmetric deviation of the Fresnel lens is improved 15.62% on average. This method improved the filling performance and replication quality of the polymer melt in the injection molding process effectively. © 2015 Optical Society of America.


Li D.,Tianjin University | Sun Y.,Tianjin University | Yu S.,Tianjin Institute of Metrological Supervision Testing | Sun C.,Tianjin University | And 2 more authors.
Sensors and Actuators, B: Chemical | Year: 2015

Abstract Currently, the implantable enzyme electrode sensor is the only method for continuous glucose monitoring in clinical applications, but the significant drift caused by bioelectricity in body and the effect of electrochemical reactions under hypoxia reduce the accuracy of the glucose measurements. Therefore, finger-prick blood corrections are often required to calibrate enzyme-based glucose sensors several times each day. In this paper, we proposed an implantable miniaturized fiber Attenuated Total Reflection (ATR) sensor based on mid-infrared spectroscopy to overcome the two drawbacks. A single-loop structure of fiber ATR sensor was used to increase the effective optical length to enhance the sensitivity. By growing silver nanoparticles (AgNPs) on the cylindrical surface of the fiber ATR sensor with a chemical silver mirror method, the sensitivity of the infrared absorption signal was further enhanced. In the experiment, the fiber ATR sensor enhanced by AgNPs combined with a CO2 laser showed an intense absorption signal from glucose, with enhancement factors of two to six folds at different absorption wavenumbers compared with the bare fiber ATR sensors. The prediction of glucose concentration with high accuracy was achieved by using the five-variable partial least-squares model yielding a root-mean-square error of prediction as small as 4.45 mg/dL. © 2015 Elsevier B.V.


PubMed | Tianjin University and Tianjin Institute of Metrological Supervision Testing
Type: | Journal: Biosensors & bioelectronics | Year: 2015

An implantable U-shaped fiber ATR sensor enhanced by silver nanoparticles on cylindrical surface was presented for continuous glucose monitoring to overcome the drawbacks of traditional glucose sensing technique based on enzyme electrodes. A U-shaped structure was addressed to increase effective optical length at limited implantable space to enhance the sensitivity of fiber ATR sensor. A novel method to fabricate silver nanoparticles on cylindrical surface of U-shaped fiber ATR sensor based on chemical reduction of its silver halide material directly without any preliminary nanoparticles synthesis and following covalent bond or self-assembly was proposed. Five glucose absorption wavelengths in the mid-infrared band were employed for specific glucose monitoring. The experimental results indicate that the sensitivity and resolution of the silver-nanoparticle-enhanced U-shaped fiber-optic ATR sensor are approximately three times those of a conventional one. The high sensitivity and low-noise performance makes it promising for in vivo glucose monitoring in the future clinical applications.


Hailiang Z.,Tianjin Institute of Metrological Supervision Testing | Shun G.,Tianjin Institute of Metrological Supervision Testing | Yong L.,Tianjin Institute of Metrological Supervision Testing | Yong R.,Tianjin Institute of Metrological Supervision Testing
2013 5th International Conference on Power Electronics Systems and Applications, PESA 2013 | Year: 2013

To achieve the coordination control of voltage and current compensation with excellent system robust, a unified power quality conditioner (UPQC) controller design procedures based on sliding mode variable structure control (SMVSC) is proposed. First, making use of high self-adaptability and strong robustness of SMVSC, linearization and decoupling control of dynamic model for UPQC could be achieved by proper nonlinear coordinate transformation and state feedback. Secondly, according to the difference between voltage and current compensation unit, different dynamic inversion management are adopted. And then, different sliding mode surfaces are select to design corresponding sliding controller. Finally, both simulation and prototype test results shows that the developed controller has excellent static and dynamic performance and the method proposed is effective and feasible. © 2013 IEEE.

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