Zheng You

Tsinghua University, Peping, Beijing, China

Are you Zheng You?

Claim your profile

Publications (98)111.38 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: MEMS relays/switches have been some of the most interesting hotspots in all kinds of MEMS devices for decades. Electrostatic actuation is the most popular actuation principle. A novel in-plane electrostatic comb-drive actuator for MEMS relays/switches was designed and fabricated. Double-tilt comb fingers and tilted parallelogram beams were proposed to achieve the requirements of MEMS relays/switches. The restoring force curve, actuation force curve, and pull-in voltage were measured. Double-tilt fingers were found to have a larger actuation force than traditional rectangular fingers, and the pull-in voltage was decreased by 25% by replacing rectangular fingers with double-tilt fingers. In addition, tilted parallelogram beams provided a convex upward restoring force curve, which was more suitable for MEMS relays/switches than the conventional force curve.
    Journal of Micromechanics and Microengineering 04/2015; 25(4). DOI:10.1088/0960-1317/25/4/045003 · 1.73 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Polarization navigation is a promising orientation-determination method inspired by insects’ foraging behavior that offers the advantages of autonomous and high precision. In this paper, using the solar meridian as an azimuth reference is proposed. The model of the distribution pattern of the polarized skylight projected onto an imaging sensor is analyzed. The sufficient features of the solar meridian are proven. According to these features, an angle algorithm for an imaging polarization navigation sensor based on a machine-vision algorithm is proposed. In consideration of noise in images, the relation between the measured angle and the noise in images is modeled. This model cannot only optimize the threshold tolerance R in the algorithm but also describe the effects of several primary factors that can affect the measuring precision. In the simulation test, the measurement accuracy was better than 0.34°. When the algorithm was tested on the polarization-detection system, the measurement accuracy was better than 0.37°.
    Optics Express 03/2015; 23(6). DOI:10.1364/OE.23.007248 · 3.53 Impact Factor
  • Jin Li, Fei Xing, Ting Sun, Zheng You
    [Show abstract] [Hide abstract]
    ABSTRACT: Modulation transfer function (MTF) can be used to evaluate the imaging performance of on-board optical remote sensing sensors, as well as recover and restore images to improve imaging quality. Laboratory measurement approaches for MTF have achieved high precision. However, they are not yet suitable for on-board measurement. In this paper, a new five-step approach to calculate MTF of space optical remote sensing sensors is proposed. First, a pixel motion model is used to extract the conditional sub-frame images. Second, a mathematical morphology algorithm and a correlation–homomorphic filter algorithm are used to eliminate noise and enhance sub-frame image. Third, an image partial differentiation determines the accurate position of edge points. Fourth, a model optical function is used to build a high-resolution edge spread function. Finally, MTF is calculated by derivation and Fourier transform. The experiment shows that the assessment method of MTF is superior to others.
    Optics Express 03/2015; 23(5). DOI:10.1364/OE.23.006187 · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Super-black materials based on Nanotechnology have very important applications in many science fields. Super-black materials which have been reported currently, although have excellent light-trapping properties, most of them need the use of sophisticated equipment , the long-time synthesis , high temperature environment and release flammable, explosive and other dangerous gases. So many kinds of problems have hindered the application of such super-black material in practice. This project had nano super-black material developed with simple equipment and process, instead of complicated and dangerous process steps in high temperature and high pressure. On the basis of literature research, we successfully worked out a set of large-area Ni-P alloy plating method through a series of experiments exploring and analyze the experimental results. In the condition of the above Ni-P alloy, we took the solution, which anodized the Ni-P alloy immersed in the non-oxidizing acid, instead of conventional blackening process. It`s a big break for changing the situation in which oxidation, corrosion, vigorous evolution of hydrogen gas in the process are performed at the same location. As a result, not only the reaction process decreased sensitivity to time error, but also the position of the bubble layer no longer located in the surface of the workpiece which may impede observing the process of reaction. Consequently, the solution improved the controllability of the blackening process. In addition, we conducted the research of nano super-black material, exploring nano-super-black material in terms of space optical sensor.
  • Dahai Ren, Jun Wang, Zheng You
    [Show abstract] [Hide abstract]
    ABSTRACT: Conventional probes used to detect proteases are susceptible to either photobleaching or low efficiency in cell penetration. Also it is difficult to achieve multiplexed detection. Based on QD, nanogold and EGF, a unique probe was studied in the paper. The sensing section of the probe was developed by linking the streptavidin-labeled QD and monomaleimide-functionalized nanogold via a substrate peptide. The QD fluorescence is partially quenched by nanogold when they were connected. After the substrate peptide is cleaved by protease, the QD fluorescence can be partially recovered as the distance between two kinds of nanoparticles increases. Biotin-labeled EGF was used to carry the sensing section into the cells, making the transfection efficiency higher than former nanoprobes. After assays, we got the optimum ratios of nanogold to QD and to EGF to constitute the probe, realized the high efficiency of both quenching and transfer. Also an algorithm was proposed to evaluate the relative activity of proteases. Finally, caspase-3 was used as the target protease to be detected. The activity of caspase-3 was successfully monitored during a longer time span compared to the reported probes.
    RSC Advances 10/2014; 4(97). DOI:10.1039/C4RA07913B · 3.71 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To improve the accuracy of digital sun sensors (DSS) to the level of arc-second while maintaining a large field of view (FOV), a multiplexing image detector method was proposed. Based on a single multiplexing detector, a dedicated mask with different groups of encoding apertures was utilized to divide the whole FOV into several sub-FOVs, every of which would cover the whole detector. In this paper, we present a novel method to analyze and optimize the diffraction effect and the parameters of the aperture patterns in the dedicated mask, including the aperture size, focal length, FOV, as well as the clearance between adjacent apertures. Based on the simulation, a dedicated mask with 13 × 13 various groups of apertures was designed and fabricated; furthermore a prototype of DSS with a single multiplexing detector and 13 × 13 sub-FOVs was built and test. The results indicated that the DSS prototype could reach the accuracy of 5 arc-second (3σ) within a 105° × 105° FOV. Using this method, the sun sensor still keeps the original features of low power consumption, small size and high dynamic range when it realizes both high accuracy and large FOV.
    Optics Express 09/2014; 22(19). DOI:10.1364/OE.22.023094 · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The calibration of micro inertial measurement units is important in ensuring the precision of navigation systems, which are equipped with microelectromechanical system sensors that suffer from various errors. However, traditional calibration methods cannot meet the demand for fast field calibration. This paper presents a fast field calibration method based on the Powell algorithm. As the key points of this calibration, the norm of the accelerometer measurement vector is equal to the gravity magnitude, and the norm of the gyro measurement vector is equal to the rotational velocity inputs. To resolve the error parameters by judging the convergence of the nonlinear equations, the Powell algorithm is applied by establishing a mathematical error model of the novel calibration. All parameters can then be obtained in this manner. A comparison of the proposed method with the traditional calibration method through navigation tests shows the classic performance of the proposed calibration method. The proposed calibration method also saves more time compared with the traditional calibration method.
    Sensors 09/2014; 14(9):16062-16081. DOI:10.3390/s140916062 · 2.05 Impact Factor
  • Peng Li, Zheng You, Tianhong Cui
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a generic approach to characterize and analyze the adhesion energy between graphene and different materials using nanoindentation of an atomic force microscope (AFM), which is extremely essential and critical for variety of graphene based micro- and nano-devices. AFM was used to press a free-standing graphene beam down to a substrate. During the retraction, the adhesion force (named as the secondary pull-off force) was measured to analyze the adhesion energy between the graphene beam and the substrate. This approach is easy for manipulation and it can detect the adhesion energy after the device fabrication. According to our measurement, the graphene/SiO2, graphene/gold, and graphene/graphene adhesion energies per area are approximately 270 mJ/m2, 255 mJ/m2, and 307 mJ/m2, respectively. This result was used to predict the performances and guide the design of graphene M/NEMS devices.
    Sensors and Actuators A Physical 09/2014; 217:56–61. DOI:10.1016/j.sna.2014.06.010 · 1.94 Impact Factor
  • Source
    Jingjing Zhao, Zheng You
    [Show abstract] [Hide abstract]
    ABSTRACT: Currently, wearable electronics are increasingly widely used, leading to an increasing need of portable power supply. As a clean and renewable power source, piezoelectric energy harvester can transfer mechanical energy into electric energy directly, and the energy harvester based on polyvinylidene difluoride (PVDF) operating in 31-mode is appropriate to harvest energy from human motion. This paper established a series of theoretical models to predict the performance of 31-mode PVDF energy harvester. Among them, the energy storage one can predict the collected energy accurately during the operation of the harvester. Based on theoretical study and experiments investigation, two approaches to improve the energy harvesting performance have been found. Furthermore, experiment results demonstrate the high accuracies of the models, which are better than 95%.
    07/2014; 2014:893496. DOI:10.1155/2014/893496
  • Source
    Jin Li, Fei Xing, Zheng You
    [Show abstract] [Hide abstract]
    ABSTRACT: Recently, the discrete wavelet transforms- (DWT-) based compressor, such as JPEG2000 and CCSDS-IDC, is widely seen as the state of the art compression scheme for charge coupled devices (CCD) camera. However, CCD images project on the DWT basis to produce a large number of large amplitude high-frequency coefficients because these images have a large number of complex texture and contour information, which are disadvantage for the later coding. In this paper, we proposed a low-complexity posttransform coupled with compressing sensing (PT-CS) compression approach for remote sensing image. First, the DWT is applied to the remote sensing image. Then, a pair base posttransform is applied to the DWT coefficients. The pair base are DCT base and Hadamard base, which can be used on the high and low bit-rate, respectively. The best posttransform is selected by the l p -norm-based approach. The posttransform is considered as the sparse representation stage of CS. The posttransform coefficients are resampled by sensing measurement matrix. Experimental results on on-board CCD camera images show that the proposed approach significantly outperforms the CCSDS-IDC-based coder, and its performance is comparable to that of the JPEG2000 at low bit rate and it does not have the high excessive implementation complexity of JPEG2000.
    07/2014; 2014:840762. DOI:10.1155/2014/840762
  • Source
    Jin Li, Fei Xing, Ting Sun, Zheng You
    [Show abstract] [Hide abstract]
    ABSTRACT: Remote sensing multispectral image compression encoder requires low complexity, high robust, and high performance because it usually works on the satellite where the resources, such as power, memory, and processing capacity, are limited. For multispectral images, the compression algorithms based on 3D transform (like 3D DWT, 3D DCT) are too complex to be implemented in space mission. In this paper, we proposed a compression algorithm based on distributed source coding (DSC) combined with image data compression (IDC) approach recommended by CCSDS for multispectral images, which has low complexity, high robust, and high performance. First, each band is sparsely represented by DWT to obtain wavelet coefficients. Then, the wavelet coefficients are encoded by bit plane encoder (BPE). Finally, the BPE is merged to the DSC strategy of Slepian-Wolf (SW) based on QC-LDPC by deep coupling way to remove the residual redundancy between the adjacent bands. A series of multispectral images is used to test our algorithm. Experimental results show that the proposed DSC combined with the CCSDS-IDC (DSC-CCSDS)-based algorithm has better compression performance than the traditional compression approaches.
    07/2014; 2014:738735. DOI:10.1155/2014/738735
  • [Show abstract] [Hide abstract]
    ABSTRACT: Star trackers and gyroscopes are the two most widely used attitude measurement devices in spacecrafts. The star tracker is supposed to have the highest accuracy in stable conditions among different types of attitude measurement devices. In general, to detect faint stars and reduce the size of the star tracker, a method with long exposure time method is usually used. Thus, under dynamic conditions, smearing of the star image may appear and result in decreased accuracy or even failed extraction of the star spot. This may cause inaccuracies in attitude measurement. Gyros have relatively good dynamic performance and are usually used in combination with star trackers. However, current combination methods focus mainly on the data fusion of the output attitude data levels, which are inadequate for utilizing and processing internal blurred star image information. A method for tracking deep coupling stars and MEMS-gyro data is proposed in this work. The method achieves deep fusion at the star image level. First, dynamic star image processing is performed based on the angular velocity information of the MEMS-gyro. Signal-to-noise ratio (SNR) of the star spot could be improved, and extraction is achieved more effectively. Then, a prediction model for optimal estimation of the star spot position is obtained through the MEMS-gyro, and an extended Kalman filter is introduced. Meanwhile, the MEMS-gyro drift can be estimated and compensated though the proposed method. These enable the star tracker to achieve high star centroid determination accuracy under dynamic conditions. The MEMS-gyro drift can be corrected even when attitude data of the star tracker are unable to be solved and only one navigation star is captured in the field of view. Laboratory experiments were performed to verify the effectiveness of the proposed method and the whole system.
    Measurement Science and Technology 07/2014; 25(8):085003. DOI:10.1088/0957-0233/25/8/085003 · 1.35 Impact Factor
  • Source
    Jingjing Zhao, Zheng You
    [Show abstract] [Hide abstract]
    ABSTRACT: Harvesting mechanical energy from human motion is an attractive approach for obtaining clean and sustainable electric energy to power wearable sensors, which are widely used for health monitoring, activity recognition, gait analysis and so on. This paper studies a piezoelectric energy harvester for the parasitic mechanical energy in shoes originated from human motion. The harvester is based on a specially designed sandwich structure with a thin thickness, which makes it readily compatible with a shoe. Besides, consideration is given to both high performance and excellent durability. The harvester provides an average output power of 1 mW during a walk at a frequency of roughly 1 Hz. Furthermore, a direct current (DC) power supply is built through integrating the harvester with a power management circuit. The DC power supply is tested by driving a simulated wireless transmitter, which can be activated once every 2-3 steps with an active period lasting 5 ms and a mean power of 50 mW. This work demonstrates the feasibility of applying piezoelectric energy harvesters to power wearable sensors.
    Sensors 07/2014; 14(7):12497-12510. DOI:10.3390/s140712497 · 2.05 Impact Factor
  • Source
    Hao Li, Gaofei Zhang, Rui Ma, Zheng You
    [Show abstract] [Hide abstract]
    ABSTRACT: An effective multisource energy harvesting system is presented as power supply for wireless sensor nodes (WSNs). The advanced system contains not only an expandable power management module including control of the charging and discharging process of the lithium polymer battery but also an energy harvesting system using the maximum power point tracking (MPPT) circuit with analog driving scheme for the collection of both solar and vibration energy sources. Since the MPPT and the power management module are utilized, the system is able to effectively achieve a low power consumption. Furthermore, a super capacitor is integrated in the system so that current fluctuations of the lithium polymer battery during the charging and discharging processes can be properly reduced. In addition, through a simple analog switch circuit with low power consumption, the proposed system can successfully switch the power supply path according to the ambient energy sources and load power automatically. A practical WSNs platform shows that efficiency of the energy harvesting system can reach about 75-85% through the 24-hour environmental test, which confirms that the proposed system can be used as a long-term continuous power supply for WSNs.
    06/2014; 2014:671280. DOI:10.1155/2014/671280
  • [Show abstract] [Hide abstract]
    ABSTRACT: The star tracker is one of the most promising attitude measurement devices widely used in spacecraft for its high accuracy. High dynamic performance is becoming its major restriction, and requires immediate focus and promotion. A star image restoration approach based on the motion degradation model of variable angular velocity is proposed in this paper. This method can overcome the problem of energy dispersion and signal to noise ratio (SNR) decrease resulting from the smearing of the star spot, thus preventing failed extraction and decreased star centroid accuracy. Simulations and laboratory experiments are conducted to verify the proposed methods. The restoration results demonstrate that the described method can recover the star spot from a long motion trail to the shape of Gaussian distribution under the conditions of variable angular velocity and long exposure time. The energy of the star spot can be concentrated to ensure high SNR and high position accuracy. These features are crucial to the subsequent star extraction and the whole performance of the star tracker.
    Optics Express 03/2014; 22(5):6009-24. DOI:10.1364/OE.22.006009 · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper investigates the type synthesis of 2T1R-type (T: translational degree of freedom (DoF) and R: rotational DoF) parallel kinematic mechanisms (PKMs). A type synthesis method based on Grassmann Line Geometry and Line-graph Method is introduced. Some basic criterions of Grassmann Line Geometry are briefly summarized, and the Line-graph Method is presented sequentially. In order to uncover the relationship between DoF-line graph and constraint-line graph, the dual rule is brought in and explained in detail. Based on these foundations, the technological process of the type synthesis is given. Thereafter, the type synthesis of 2T1R-type PKMs is carried out and the results are listed. Taken as an application example, a synthesized 3-DoF mechanism is chosen as the parallel module of a five-axis hybrid machine tool, which is capable of five-face machining in one setup. The developed prototype is introduced and applied into the machining of a part with freeform surfaces. The presented type synthesis method is concise and can be used in the type synthesis of other PKMs.
    Robotics and Computer-Integrated Manufacturing 02/2014; 30(1):1–10. DOI:10.1016/j.rcim.2013.07.002 · 1.84 Impact Factor
  • Mathematical Problems in Engineering 01/2014; 2014:1-16. DOI:10.1155/2014/432613 · 1.08 Impact Factor
  • Jin Li, Fei Xing, Ting Sun, Zheng You
    Journal of Applied Mathematics 01/2014; 2014:1-8. DOI:10.1155/2014/374285 · 0.72 Impact Factor
  • Source
    Minsong Wei, Fei Xing, Zheng You
    [Show abstract] [Hide abstract]
    ABSTRACT: Stringent attitude determination accuracy through a high bandwidth is required for the development of the advanced space technologies, such as earth observation and laser communication. In this work, we presented a novel proposal for a digital sun sensor with high accuracy, large Field of View (FOV) and ultra-high data update rate. The Electronic Rolling Shutter (ERS) imaging mode of an APS CMOS detector was employed and an "amplifier factor" was introduced to improve the data update rate significantly. Based on the idea of the multiplexing detector, a novel mask integrated with two kinds of aperture patterns was also introduced to implement its distinctive performance of high precision and large FOV. Test results show that the ERS based sun sensor is capable of achieving the data update rate of 1 kHz and precision of 1.1″ (1σ) within a 105° × 105° FOV. The digital sun sensor can play an important role in precise attitude determination and provide a broader application for high accuracy satellites.
    Optics Express 12/2013; 21(26):32524-33. DOI:10.1364/OE.21.032524 · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Bio-MEMS technique of organizing cells in single cell arrays makes it easier to observe cells' individual characteristics and behaviors, which is of benefit for basic cell research and high throughout drug screening. We utilized photolithography and chemical vapor deposition (CVD) to pattern hydrophobic hexamethyldisilazane (HMDS) islands and hydrophilic polyethylene glycol (PEG)-Silane regions on 25 mm 25 mm glass slides. Compared with methods presently used, the photoresist wells can be more stable, and clear HMDS island arrays can be formed. We adopted a better and more powerful medium, the Biotin-(Strept)Avidin System to fix cells on the specified regions of the substrate. This is more efficient than the former medium, antibodies and antigens. Moreover, using a biotinylating cell surface, we produced more biotins on the surface of the cells and made it easier to capture cells and avoid washing away fixed cells. By changing the concentration of cell suspension for seeding, we found a suitable concentration (5 x 10(6) cells/ml), at which the cell occupation was greater than 90%. By comparing various diameters of streptavidin islands, optimal diameters (14-20 mu m) were found to capture single human promyelocytic leukemia cells (HL-60). With all optimal parameters, single cell arrays were formed. The ratio of islands capturing only one cell was approximately 77%, which is better than similar approaches.
    Sensors and Actuators B Chemical 11/2013; 188:340-346. DOI:10.1016/j.snb.2013.07.037 · 3.84 Impact Factor