High-precision Sampling Research Articles

Development of Special Users' Energy Saving Potential New Intelligent Diagnosis Detector Based on DSP2812 Technology

In order to solve the problem that special users energy saving potential is unable to diagnose automotive online, a new automatic diagnosis of energy saving potential method based on online DSP was proposed. This proposed method, together with a variety of techniques like modern power electronics, digital signal processing, high precision and fast sampling, high capacity storage, human-machine interaction technologies and so on, was applied to develop a corresponding special users energy saving potential diagnosis detector. The hardware design and DSP energy saving analysis software design of the detector were described firstly, and the results of field test were presented to demonstrate its feasibility. It is shown that, its advantages include easy-to-use, low cost, highly reliable, strong intelligence and easy to promote, thus can effectively improve the efficiency of electrical energy audit and the degree of information and automation.

Rapid Determination of Prochloraz in Orange Juice by Near-Infrared Spectroscopy

Near-infrared spectroscopy, which has advantages of high speed, high precision, and minimal sample preparation, is a rapid, solvent-free, on-site quantitative and qualitative analytical method. This study assessed the feasibility of using near-infrared spectroscopy to determine prochloraz residue in orange juice. Two chemometric methods, partial least-squares discriminant analysis and least-squares support vector machines, were employed to create mathematical models to classify three spectrum bands. The selected spectral values ranged from 5,030 to 5,100 cm−1. The results show the least-squares support vector model outperformed the discriminant analysis algorithm. Classification accuracy of 100% was obtained for the calibration set and the prediction set of the former when the two parameters, γ and σ2 were 20.5707 and 2.48703, respectively, while the classification accuracy of the discriminant analysis method for the calibration set and the prediction set were 100% and 96.8%, respectively. By contrast, it is easy to conclude that when the limit of detection of the proposed method is set as low as 0.5 µg mL−1, the support vector model has the capability to predict the presence or absence of prochloraz residue, whereas the discriminant analysis model may give false positives. Considering the analytical process for a sample takes only about one minute, the proposed method ensures the simplicity and reliability in practical applications. The results of the study showed the potential of near-infrared spectroscopy as a rapid and environmentally friendly method for the on-site screening of prochloraz in orange juice.

Linear electrooptic coefficient r_51 of tetragonal potassium lithium tantalate niobate K_095Li_005Ta_040Nb_060O_3 single crystal

The linear electrooptic r51 coefficient of tetragonal K0.95Li0.05Ta0.40Nb0.60O3 single crystal was measured and reported. A modified AC modulating method coupled with high precision sample positioner, coherent light source, and phase-locked signal detection, was used to measure the electric field induced rotation of optical axis. The electrooptic r51 coefficient was found to be exceptionally large, r51 = (1.10 ± 0.14) × 104 pm/V at room temperature. Altogether with high ferroelectric phase transition temperature (~440 K), good optical crystal quality, ultrahigh linear electrooptic r51 coefficient and low frequency dependency, the K0.95Li0.05Ta0.40Nb0.60O3 single crystal offers significant application potential for various electrooptic devices.

A Two-Stage Distributed Architecture for DAQ in Thousand-channel Physics Experiments

This manuscript presents a two-stage distributed architecture for DAQ (data acquisition) of thousand-channel large-area wire sensor networks for use in physics experiments. This architecture can be divided into two units, one for data concentration and recording, system control, and monitoring, and another for data sampling and transmission. The most prominent characteristics of this architecture include real-time capability, high-precision synchronous data sampling, and scalability. A prototype of this two-stage distributed architecture has been built. It can support up to 16 data sampling cables containing 1920 channels each. Sampling synchronization, data transmission, and storage were assessed via a customized simulator. Test results show that the sampling synchronization error between two channels 100 m apart was in the range of 1 ns. The maximum data rate reached up to 92.16 Mbps per cable, so the total data rate was about 1474 Mbps for 16 cables (30, 720 channels).

Simultaneous determination of nanomolar nitrite and nitrate in seawater using reverse flow injection analysis coupled with a long path length liquid waveguide capillary cell

A reverse flow injection analysis (rFIA) method coupled with 1m liquid waveguide capillary cell and spectrophotometric detection for simultaneous determination of nanomolar nitrite and nitrate in seawater was developed. The design of two analytical channels sharing the same detection system in the proposed method allowed the analysis of both nitrite and nitrate with single sample injection. Different strategies of reagent injection were investigated to obtain a higher sensitivity and a better peak shape. A dual-wavelength detection mode was chosen to eliminate the light source shifting and sample matrix interference. Experimental parameters were optimized based on a univariate experimental design and the matrix effect from seawater was preliminarily investigated. The proposed method had high sensitivity with detection limit of 0.6 nmol L(-1) for both nitrite and nitrate. The linearity was 2-500 nmol L(-1) for both analytes, and the upper limit could be extended by choosing a lower sensitivity detection wavelength. The analytical results of 26 surface seawater samples obtained with the proposed method showed good agreement with those using a reference method operated using an automated segmented flow analyzer. The proposed method could greatly minimize the trouble introduced by bubbles in the segmented flow analyzer. It also had the advantages of high precision and high sample throughput (nitrite and nitrate detected in triplicate; 5 h(-1)). Compared to normal flow injection analysis, the rFIA method is superior due to its lower reagent consumption, less dispersion of sample, as well as higher sensitivity.

The Fiber Grating Signal Acquisition System Design Based on FPGA and USB Interface

Design a high-precision real-time high-speed sampling fiber grating demodulation signal system based on a USB2.0 interface and FPGA; system hardware design and software design are introduced in detail. It is proved that has a good reliability and stability by the experiment. So this design has a strong value in use.

Application of VFC in High Voltage Sampling System Based on CPLD

A VFC technique based on CPLD is proposed, by which the problems of isolation and remote transmission emerged in high voltage sampling systems could be well solved. The working principle, circuit configuration, and hardware realization of VFC are introduced in detail, respectively in this paper. Moreover, the problems of operation principle and conversion accuracy of VFC based on CPLD are emphasized and the corresponding method of V/F transition is proposed utilizing CPLD and DSP. Due to some significant advantages, such as, high voltage in circuit isolation, high sampling precision, easy realization, and the satisfaction in remote transition requirement, the developed VFC sampling system could be widely utilized in high voltage sampling systems. Finally, some experimental results are provided to show the effectiveness of the proposed VFC technique based on CPLD.

Research Status and Prospect of Rock Mass Acoustic Emission Instrument

Acoustic emission technique based on sampling and disposing of the elastic wave caused by rock mass deformation, can comprehend the internal force, damaged degree of target component or material. Acoustic emission system as a dynamic non-destructive testing program, has now been widely used in various fields of engineering. Research on rock mass acoustic emission technology is to identify the stable status of the rock mass by using acoustic emission instrument to receive the elastic wave. Rock mass acoustic emission instrument requires high precision and high sampling frequency. The research status of the acoustic emission instrument and the problems appears in developing the device introduced in this article could be the reference for the future study.

Offshore towed hydrophone linear array: principle, application, and data acquisition results

Abstract An underwater acoustic sensing array was presented in this article. With the high-precision sampling clock generation and transmission system, the array can acquire signals synchronously in sub-microsecond level, which is important in offshore environment. Meanwhile, real-time data transmission and storage system was established. All of the data received in host computer can be saved and displayed immediately. Data acquisition experiment was implemented in freshwater reservoir near Tianjin city,China, and the results of the signal wave show that the acquisition and transmission system of hydrophone array can be used to get the underwater information by acoustic exploration.

An Improved Digital Servo Burst Signal Sampling Model for Disk Drives

In order to calculate the servo position error signal (PES) in the servo system, it is necessary to make high precision sampling and FFT calculation for the burst signal. Most designer s adopt 8bits ADC converter in the read write channel servo system of hard drive controller chip 88i6310 to cost down, and both servo system and signal system share the sampling circuit. Because of the quantitative noise disturbing during the sampling process, it is not enough to use 6bits ADC converter for the serve burst signal, and significant error exist for t he burst signal with the FFT calculation. This paper analyzed the existing servo over-sampling model via quantitative error model firstly, and provided the enhanced servo system sampling model. The simulation shows that, the enhanced solution reduces the average quantitative error from 0. 38 LSB to 0.14LSB, and improves the resolution of ADC converter from 9.5 bits to 10.8 bits.

Sub-500-nm patterning of glass by nanosecond KrF excimer laser ablation

The surface of flint glass of type F2 is patterned by nanosecond KrF excimer laser ablation. Strong UV absorption provides a comparatively low ablation threshold and precise ablation contours. By using a two-grating interferometer, periodic surface patterns with 330 nm period and 100 nm modulation depth are obtained. This method enables the fabrication of 7 mm×13 mm wide grating areas with perfectly aligned grooves without the need of high-precision sample positioning. By double exposure, crossed gratings with adjustable depths in the two orthogonal directions can be generated.

Design and performance of a combined secondary ion mass spectrometry-scanning probe microscopy instrument for high sensitivity and high-resolution elemental three-dimensional analysis

State-of-the-art secondary ion mass spectrometry (SIMS) instruments allow producing 3D chemical mappings with excellent sensitivity and spatial resolution. Several important artifacts however arise from the fact that SIMS 3D mapping does not take into account the surface topography of the sample. In order to correct these artifacts, we have integrated a specially developed scanning probe microscopy (SPM) system into a commercial Cameca NanoSIMS 50 instrument. This new SPM module, which was designed as a DN200CF flange-mounted bolt-on accessory, includes a new high-precision sample stage, a scanner with a range of 100 μm in x and y direction, and a dedicated SPM head which can be operated in the atomic force microscopy (AFM) and Kelvin probe force microscopy modes. Topographical information gained from AFM measurements taken before, during, and after SIMS analysis as well as the SIMS data are automatically compiled into an accurate 3D reconstruction using the software program "SARINA," which was developed for this first combined SIMS-SPM instrument. The achievable lateral resolutions are 6 nm in the SPM mode and 45 nm in the SIMS mode. Elemental 3D images obtained with our integrated SIMS-SPM instrument on Al/Cu and polystyrene/poly(methyl methacrylate) samples demonstrate the advantages of the combined SIMS-SPM approach.

Sample Clock Offset Detection and Correction in the LTE Downlink

The narrow subcarrier spacing and wide bandwidth arrangement in the LTE downlink produce a vulnerability to sample clock mismatch between the transmitting and receiving data converters. Without high precision sampling clock frequencies, a high level of inter-carrier interference (ICI) is introduced, yielding undesirable performance. In this article, a method to jointly estimate and correct sampling frequency mismatch is proposed. The proposed method uses information already known to the receiver, operates strictly in the time domain and does not require the aid of pilot symbols or other frequency domain information. The method allows clocks with lower precision to be used with minimal performance degradation. Results are presented using MATLAB simulation as well as an FPGA hardware implementation.

The HARPS search for southern extra-solar planets

We present the discovery of four new long-period planets within the HARPS high-precision sample: \object{HD137388}b ($M\sin{i}$ = 0.22 $M_J$), \object{HD204941}b ($M\sin{i}$ = 0.27 $M_J$), \object{HD7199}b ($M\sin{i}$ = 0.29 $M_J$), \object{HD7449}b ($M\sin{i}$ = 1.04 $M_J$). A long-period companion, probably a second planet, is also found orbiting HD7449. Planets around HD137388, HD204941, and HD7199 have rather low eccentricities (less than 0.4) relative to the 0.82 eccentricity of HD7449b. {All these planets were discovered even though their hosting stars have clear signs of activity. Solar-like magnetic cycles, characterized by long-term activity variations, can be seen for HD137388, HD204941 and HD7199, whereas the measurements of HD7449 reveal a short-term activity variation, most probably induced by magnetic features on the stellar surface. We confirm that magnetic cycles induce a long-term radial velocity variation and propose a method to reduce considerably the associated noise.} The procedure consists of fitting the activity index and applying the same solution to the radial velocities because a linear correlation between the activity index and the radial velocity is found. Tested on HD137388, HD204941, and HD7199, this correction reduces considerably the stellar noise induced by magnetic cycles and allows us to derive precisely the orbital parameters of planetary companions.

A parametrically amplified MEMS rate gyroscope

This paper reports a parametrically amplified MEMS rate gyroscope. A practical parametric excitation scheme implemented using Digital Signal Processing (DSP) has been developed to enable either amplification of the primary mode of the gyroscope or amplification of the response to the applied angular velocity. The primary objective of this work is to improve the scale-factor and the signal to noise performance of the gyroscope. Parametric amplification of the primary mode of the gyroscope is achieved by frequency tracking and regulation of the amplitudes of the harmonic forcing and parametric excitation to maintain a desired parametric gain by closed loop PID control. Stable parametric amplification of the primary mode by a factor of 20 is demonstrated experimentally. This has important benefits regarding the minimisation of electrical feedthrough of the drive signal to the sense electrodes of the secondary mode. By taking advantage of the phase dependence of parametric amplification and the orthogonality of the Coriolis force and quadrature forcing, the response to the applied angular velocity may be parametrically amplified by applying excitation of a particular phase directly to the sensing mode. The major advantage of parametric amplification applied to MEMS gyroscopes is that it can mechanically amplify the Coriolis response before being picked off electrically. This is particularly advantageous for sensors where electronic noise is the major noise contributor. In this case parametric amplification can significantly improve the signal to noise ratio of the secondary mode by an amount approximately equal to the parametric amplification. Preliminary rate table tests performed in open loop demonstrate a magnification of the signal to noise ratio of the secondary mode by a factor of 9.5 and the scale-factor by 11. The excitation and control scheme have been implemented digitally using a DSP development board enabling very high sampling precision and execution speed necessary for gyroscopic applications.

High definition profiling of mammalian DNA methylation by array capture and single molecule bisulfite sequencing

DNA methylation stabilizes developmentally programmed gene expression states. Aberrant methylation is associated with disease progression and is a common feature of cancer genomes. Presently, few methods enable quantitative, large-scale, single-base resolution mapping of DNA methylation states in desired regions of a complex mammalian genome. Here, we present an approach that combines array-based hybrid selection and massively parallel bisulfite sequencing to profile DNA methylation in genomic regions spanning hundreds of thousands of bases. This single molecule strategy enables methylation variable positions to be quantitatively examined with high sampling precision. Using bisulfite capture, we assessed methylation patterns across 324 randomly selected CpG islands (CGI) representing more than 25,000 CpG sites. A single lane of Illumina sequencing permitted methylation states to be definitively called for >90% of target sties. The accuracy of the hybrid-selection approach was verified using conventional bisulfite capillary sequencing of cloned PCR products amplified from a subset of the selected regions. This confirmed that even partially methylated states could be successfully called. A comparison of human primary and cancer cells revealed multiple differentially methylated regions. More than 25% of islands showed complex methylation patterns either with partial methylation states defining the entire CGI or with contrasting methylation states appearing in specific regional blocks within the island. We observed that transitions in methylation state often correlate with genomic landmarks, including transcriptional start sites and intron-exon junctions. Methylation, along with specific histone marks, was enriched in exonic regions, suggesting that chromatin states can foreshadow the content of mature mRNAs.

Kinematic reconstruction of atmospheric neutrino events in a large water Cherenkov detector with proton identification

We report the development of a proton identification method for the Super-Kamiokande (SK) detector. This new tool is applied to the search for events with a single proton track, a high purity neutral current sample of interest for sterile neutrino searches. After selection using a neural network, we observe 38 events in the combined SK-I and SK-II data corresponding to 22 85.1 days of exposure, with an estimated signal-to-background ratio of 1.6 to 1. Proton identification was also applied to a direct search for charged-current quasielastic (CCQE) events, obtaining a high precision sample of fully kinematically reconstructed atmospheric neutrinos, which has not been previously reported in water Cherenkov detectors. The CCQE fraction of this sample is 55%, and its neutrino (as opposed to antineutrino) fraction is 91.7{+-}3%. We selected 78{mu}-like and 47 e-like events in the SK-I and SK-II data set. With this data, a clear zenith angle distortion of the neutrino direction itself is reported in a sub-GeV sample of {mu} neutrinos where the lepton angular correlation to the incoming neutrino is weak. Our fit to {nu}{sub {mu}}{yields}{nu}{sub {tau}} oscillations using the neutrino (L/E) distribution of the CCQE sample alone yields a wide acceptance region compatible with our previousmore » results and excludes the no-oscillation hypothesis at 3-sigma.« less

High-precision sample stage for photoemission microscopy of organic films

A high-precision sample stage for photoemission microscopy has been constructed to translate the sample by ±3 mm with accuracy better than 100 nm. The stage is actuated by step motors settled outside the vacuum. The accuracies of the translations were measured by observing a standard patterned sample with a photoemission electron microscope (PEEM) of 50 nm resolution. The accuracy was nearly independent of the distance of each translation step and the error was not accumulated by repeated steps. After round-trip translations up to 0.2 mm, the sample came back to the original position with accuracy of ±50 nm. The performance of the stage was demonstrated by observing growth processes of lead phthalocyanine (PbPc) films formed on graphite.

X-ray diffractometry for the structure determination of a submicrometre single powder grain

A high-precision diffractometer has been developed for the structure analysis of a submicrometre-scale single grain of a powder sample at the SPring-8 BL40XU undulator beamline. The key design concept is the combination of a stable focused synchrotron radiation beam and the precise axis control of the diffractometer, which allows accurate diffraction intensity data of a submicrometre-scale single powder grain to be measured. The phase zone plate was designed to create a high-flux focused synchrotron radiation beam. A low-eccentric goniometer and high-precision sample positioning stages were adopted to ensure the alignment of a micrometre-scale focused synchrotron radiation beam onto the submicrometre-scale single powder grain. In order to verify the diffractometer performance, the diffraction pattern data of several powder grains of BaTiO(3), of dimensions approximately 600 x 600 x 300 nm, were measured. By identifying the diffraction data set of one single powder grain, the crystal structure was successfully determined with a reliable factor of 5.24%.

Precise orbit determination of a maneuvered GEO satellite using CAPS ranging data

Wheel-off-loadings and orbital maneuvers of the GEO satellite result in additional accelerations to the satellite itself. Complex and difficult to model, these time varying accelerations are an important error source of precise orbit determination (POD). In most POD practices, only non-maneuver orbital arcs are treated. However, for some applications such as satellite navigation RDSS services, uninterrupted orbital ephemeris is demanded, requiring the development of POD strategies to be processed both during and after an orbital maneuver. We in this paper study the POD for a maneuvered GEO satellite, using high precision and high sampling rate ranging data obtained with Chinese Area Positioning System (CAPS). The strategy of long arc POD including maneuver arcs is studied by using telemetry data to model the maneuver thrust process. Combining the thrust and other orbital perturbations, a long arc of 6 days’ CAPS ranging data is analyzed. If the telemetry data are not available or contain significant errors, attempts are made to estimate thrusting parameters using CAPS ranging data in the POD as an alternative to properly account for the maneuver. Two strategies achieve reasonably good data fitting level in the tested arc with the maximal position difference being about 20 m.