Dynamic Measurement Method Research Articles

Characterization of an Electrically Controlled Metamaterial Terahertz Modulator Using Dynamic Measurement Method

The characterization results of a typical electrically controlled metamaterial terahertz (THz) modulator obtained by the dynamic measurement method are presented and are in good agreement with the theoretical results predicted by a first-order model. The dynamic measurement method can characterize the modulation depth and modulation speed simultaneously. The reliability of the method is verified by terahertz time-domain spectroscopy (THz-TDS), and the current response method, which show that the more intuitive and comprehensive dynamic measurement method, can be used to characterize the electrically controlled metamaterial THz modulator accurately.

Dynamic Measurement for the Diameter of A Train Wheel Based on Structured-Light Vision.

Wheels are very important for the safety of a train. The diameter of the wheel is a significant parameter that needs regular inspection. Traditional methods only use the contact points of the wheel tread to fit the rolling round. However, the wheel tread is easily influenced by peeling or scraping. Meanwhile, the circle fitting algorithm is sensitive to noise when only three points are used. This paper proposes a dynamic measurement method based on structured-light vision. The axle of the wheelset and the tread are both employed. The center of the rolling round is determined by the axle rather than the tread only. Then, the diameter is calculated using the center and the contact points together. Simulations are performed to help design the layout of the sensors, and the influences of different noise sources are also analyzed. Static and field experiments are both performed, and the results show it to be quite stable and accurate.

Objective measures on knee instability: dynamic tests: a review of devices for assessment of dynamic knee laxity through utilization of the pivot shift test.

Current reconstructive methods used after anterior cruciate ligament (ACL) injury do not entirely restore native knee kinematics. Evaluation of dynamic knee laxity is important to accurately diagnose ACL deficiency, to evaluate reconstructive techniques, and to construct treatment algorithms for patients with ACL injury. The purpose of this study is to present recent progress in evaluation of dynamic knee laxity through utilization of the pivot shift test. A thorough electronic search was performed and relevant studies were assessed. Certain dynamic knee laxity measurement methods have been present for over 10years (Navigation system, Electromagnetic sensor system) while other methods (Inertial sensor, Image analysis system) have been introduced recently. Methods to evaluate dynamic knee laxity through the pivot shift test are already potent. However, further refinement is warranted. In addition, to correctly quantify the pivot shift test, the involved forces need to be controlled through either standardization or mechanization of the pivot shift test.

Dynamic specular surface measurement based on color-encoded fringe reflection technique

A color-encoded fringe reflection technique is presented for dynamic specular surface measurement. Only one color-encoded fringe pattern is required in this method. In comparison with the reported dynamic specular surface measuring method (the composite fringe pattern method), the proposed color-encoded fringe technique has higher phase accuracy. The color intensity crosstalk problem between the three channels is discussed. As a result, this problem will seldom affect the phase accuracy of the proposed method. This turns out to be the main reason why the presented method can achieve a higher measuring accuracy than the existing dynamic measurement method. In addition, the proposed color-encoded fringe technique is proven to be more suitable than the existing method for the complex tested surface. The vibrating measuring experiment of a wafer proves the ability of the proposed method to achieve dynamic measurement.

A Review of Machine Vision-Based Structural Health Monitoring: Methodologies and Applications

In the past two decades, a significant number of innovative sensing and monitoring systems based on the machine vision-based technology have been exploited in the field of structural health monitoring (SHM). This technology has some inherent distinctive advantages such as noncontact, nondestructive, long distance, high precision, immunity to electromagnetic interference, and large-range and multiple-target monitoring. A lot of machine vision-based structural dynamic measurement and structural state inspection methods have been proposed. Real-world applications are also carried out to measure the structural physical parameters such as the displacement, strain/stress, rotation, vibration, crack, and spalling. The purpose of this review article is devoted to presenting a summary of the basic theories and practical applications of the machine vision-based technology employed in structural monitoring as well as its systematic error sources and integration with other modern sensing techniques.

基于时序推延的线阵CCD 动态位移测量方法研究

基于时序推延的线阵CCD 动态位移测量方法研究

Analysis of Intracellular Ca(2+) Mobilization in Human NK Cell Subsets by Flow Cytometry.

In signaling cascades downstream of NK cell activating receptor engagement, Ca(2+) ions are pivotal second messengers for NK cell cytotoxicity as well as cytokine production. Upon cellular activation, intracellular mobilization of Ca(2+) ions initially involves depletion of endoplasmic reticulum stores, leading to subsequent Ca(2+) influx through specific plasma membrane Ca(2+) release activated Ca(2+) channels. Multiple probes and assays for detecting intracellular Ca(2+) concentrations have been developed. With the advance of multiparameter flow cytometry instrumentation, a thorough analysis of signaling in specific NK cell subsets is possible. Here, a flow cytometric method for dynamic measurements of intracellular Ca(2+) concentrations in human NK cells subsets is detailed and discussed. This assay can be further adapted for specific scientific and diagnostic questions, with implications for various immunopathological conditions.

A FDTD Simulation on YIG Based 2D Magnetic Photonic Crystal

This paper mentioned a FDTD simulation on the optical propagation in plane and along the z axis, we analysis the MPC structure, filling factor, dielectric constant, and their affects on the optical bandgap. This study put special attention on the polarization phenomena. Through simulation we observed the real time change of light （especially on polarization）in 2D MPC, obtaining the relationship curve between polarization angle and polarization degree to the MPC structure and filling factor. Based on FDTD aglorithm, this change reflects the Faraday effect from micro-level. Finally we suggest a dynamic measurement method based on Fetosecond laser, in order to realize time-divided Faraday effect.

磁歪効果を利用した微小疲労き裂情報の測定

Small fatigue crack closure is observed as a thing with a possibility that the influence of change of the stress level and a stress ratio, etc. to the crack growth behavior can be explained, and until now various researches have been done. Although there is a method using the strain gage as the dynamic measurement method required for the elucidation of a minute fatigue crack, in respect of generating of minute fatigue cracks being directly contacted to a measuring object thing, and there is a problem in durability or measurement of the crack growth behavior, it may not necessarily be effective. Then, its attention was paid to the magnetostriction effect which is one of the magnetic actions of a ferromagnetic substance. Measurement of the opening stress of the minute fatigue crack under dynamic load and crack length performed by measuring the magnetic field change by the magnetostriction effect, without needing the contact to an object with simple equipment.

Energy asymmetry in melting and solidifying processes of PCM

The solidifying process of phase change material (PCM) was usually recognized as the exact inverse process of its melting process, especially when building the heat transfer model of PCM. To figure out that whether the melting process and the solidifying process of PCM were symmetrical, several kinds of PCMs were tested by a differential scanning calorimeter (DSC) in this paper. The experimental results showed that no matter using the DSC dynamic measurement method or the DSC step measurement method, the melting process and the solidifying process of PCM were asymmetrical. Because of the energy asymmetry in the melting and solidifying processes of PCM, it was also found that the enthalpy and the state of PCM were not only dependent on its temperature, but also affected by its “previous state”.

Transverse vibrations of a thin loaded rod: theory and experiment

The general formulation of a determinate solution problem is deduced for the transverse vibrations of a thin loaded rod. The vibration frequencies of a thin homogeneous rod carrying a concentrated mass as a function of the load’s position and mass are exactly solved. The dynamic measurement method of Young’s modulus of the rods is presented within this theory. Our measurements of Young’s modulus in the dynamic method agree with those in the traditional bending method, therefore the theory is verified by our experiments.

Comparison of Adaptive and Model-Free Methods for Dynamic Measurement

Dynamic measurement aims to improve the speed and accuracy characteristics of measurement devices by signal processing. State-of-the-art dynamic measurement methods are model-based adaptive methods, i.e., 1) they estimate model parameters in real-time and 2) based on the identified model perform model-based signal processing. The proposed model-free method belongs to the class of the subspace identification methods. It computes directly the quantity of interest without an explicit parameter estimation. This allows efficient computation as well as applicability to general high order multivariable processes.

A New Measurement Circuit to Evaluate Current Collapse Effect of GaN HEMTs Under Practical Conditions

The gallium nitride transistors suffer from current collapse effect in operation regions, which leads the dynamic ON-resistance to increase when high voltage is applied to the transistor. Dynamic ON-resistance under practical application conditions is also an important factor for the reliability and conduction efficiency of transistors. To measure the dynamic ON-resistance and evaluate the current collapse effect, a softswitching circuit based on synchronous buck topology is proposed in this paper. To apply high-voltage and high-current stresses to the device without additional spikes and oscillation, resonance technique has been employed. As a result, the proposed circuit could produce sufficient power stresses to the devices with general equipment. To achieve accurate measurement of ON-resistance under switching operations and eliminate the saturation of oscilloscope probes, an active voltage clamp circuit is developed. Operation principles and design analysis of the circuit are described in this paper. The dynamic ON-resistance measurement method is illustrated in detail. Furthermore, a prototype circuit has been built. A simulation and experiments were carried out to verify the performance of the system. A comparison of the active clamp circuit with common voltage probes is presented through the measurement results. The experimental results confirm that dynamic ON-resistance can be accurately measured using the proposed circuit and the current collapse effect can be evaluated under practical operation conditions with high precision.

Dynamic tread wear measurement method for train wheels against vibrations.

Dynamic tread wear measurement is difficult but significant for railway transportation safety and efficiency. The accuracy of existing methods is inclined to be affected by environmental vibrations since they are highly dependent on the accurate calibration of the relative pose between vision sensors. In this paper, we present a method to obtain full wheel profiles based on automatic registration of vision sensor data instead of traditional global calibrations. We adopt two structured light vision sensors to recover the inner and outer profiles of each wheel, and register them by the iterative closest point algorithm. Computer simulations show that the proposed method is insensitive to noises and relative pose vibrations. Static experiments demonstrate that our method has high accuracy and great repeatability. Dynamic experiments show that the measurement accuracy of our method is about 0.18 mm, which is a twofold improvement over traditional methods.

Dynamic measurement of high-frequency deflections of the vertical based on the observation of INS/GNSS integration attitude error

A novel method for dynamic measurement of deflections of the vertical (DOVs) by using the integration of inertial navigation system (INS) and global navigation satellite system (GNSS) has been proposed. Since the attitude errors of INS/GNSS integrated system are directly related to DOV, it is expected that DOV can be also estimated via the observation of INS/GNSS attitude errors. First, an attitude reference decoupled from DOV is constructed with the raw gyroscope data of the INS for INS/GNSS attitude error calculation. Then, DOV and various systematic errors including attitude reference error and inertial sensor errors are accurately modeled. The long-wavelength components of DOV are given by global gravity model, and the short-wavelength components are modeled as derivative second-order Gauss–Markov processes. Finally, DOV and systematic errors are simultaneously estimated by a Kalman smoother with the observation of INS/GNSS attitude error. A ship-borne survey campaign is conducted to validate the feasibility of the proposed method. Four sets of DOV data were obtained by two INS/GNSS integrated navigation systems along with two repeated survey lines. The experimental results show that the internal accuracy of the four sets of DOV data can reach better than 0.35″(1σ). When wavenumber correlation filter (WCF) algorithm is applied to the DOV data obtained by each system along the repeated lines, the DOV estimates from the two systems show good consistency, and the internal accuracy can be improved to about 0.2″(1σ).

Discussion of “New Method for High-Speed Railway Bridge Dynamic Deflection Measurement” by Xianlong He, Xueshan Yang, and Lizhen Zhao

Discussion of “New Method for High-Speed Railway Bridge Dynamic Deflection Measurement” by Xianlong He, Xueshan Yang, and Lizhen Zhao

Flexible dynamic measurement method of three-dimensional surface profilometry based on multiple vision sensors.

Single vision sensor cannot measure an entire object because of their limited field of view. Meanwhile, multiple rigidly-fixed vision sensors for the dynamic vision measurement of three-dimensional (3D) surface profilometry are complex and sensitive to strong environmental vibrations. To overcome these problems, a novel flexible dynamic measurement method for 3D surface profilometry based on multiple vision sensors is presented in this paper. A raster binocular stereo vision sensor is combined with a wide-field camera to produce a 3D optical probe. Multiple 3D optical probes are arranged around the object being measured, then many planar targets are set up. These planar targets function as the mediator to integrate the local 3D data measured by the raster binocular stereo vision sensors into the coordinate system. The proposed method is not sensitive to strong environmental vibrations, and the positions of these 3D optical probes need not be rigidly-fixed during the measurement. The validity of the proposed method is verified in a physical experiment with two 3D optical probes. When the measuring range of raster binocular stereo vision sensor is about 0.5 m × 0.38 m × 0.4 m and the size of the measured object is about 0.7 m, the accuracy of the proposed method could reach 0.12 mm. Meanwhile, the effectiveness of the proposed method in dynamic measurement is confirmed by measuring the rotating fan blades.

G0300207 磁気的特性を利用した微小疲労き裂情報の測定

Small fatigue crack closure is observed as a thing with a possibility that the influence of change of the stress level and a stress ratio, etc. to the crack growth behavior can be explained, and until now various researches have been done. Although there is a method using the strain gage as the dynamic measurement method required for the elucidation of a minute fatigue crack, in respect of generating of minute fatigue cracks being directly contacted to a measuring object thing, and there is a problem in durability or measurement of the crack growth behavior, it may not necessarily be effective. Then, its attention was paid to the magnetostriction effect which is one of the magnetic actions of a ferromagnetic substance. Measurement of the opening stress of the minute fatigue crack under dynamic load and crack length performed by measuring the magnetic field change by the magnetostriction effect, without needing the contact to an object with simple equipment. Moreover, it measured by having changed cross-sectional shape of the specimen. Resulting in, opening stress of the minute fatigue crack opening stress was able to measure about specimen regardless of the cross-sectional shape of the specimen. However, at this stage, it is possible to perform a crack length measurement can only specimen having a circular cross-section.

Abstract 16726: Dynamic Analysis of the Tricuspid Annulus -Does Non Planarity of the Annulus Matter?

Introduction: Surgical decision-making on the tricuspid valve (TV) hinges on accurate measurements of the tricuspid annulus (TA). 3D echocardiography is more accurate than 2D for dynamic measurement of TA size due to TA non-planarity. Multiplanar reconstruction (MPR) of 3D datasets is easily performed on ultrasound machines but results in inconsistent measurements of minimum and maximum TA size. We developed an alternative method for dynamic TA measurement that accounts for TA non-planarity, to determine if this approach would yield different annulus sizes compared to the MPR method. Methods: 51 normal subjects underwent 3D TTE of the TA (Philips). MPR measurements of the TA were made on a plane passing through 2 pairs of hinge points identified in orthogonal apical views (QLAB, fig.A). The alternative approach used custom software (CS) that initialized TA hinge points in mid-systole (MS) in multiple rotated planes, following the non-planar shape of the TA (fig. B); these were then tracked throughout the cardiac cycle. TA area, antero-posterior and septal-lateral dimensions were measured at end-diastole (ED, TV closure), MS and end-systole (ES, prior to TV opening), and compared between approaches. Results: MPR measurements showed minimum TA size at ED or MS. In contrast, the CS approach resulted in significantly larger measurements and showed minimum TA size at ES (Table). Careful review revealed that in many patients the annular plane in which MPR measurements were made cut through parts of the right atrial (RA) walls. Conclusions: MPR-based TA size may be underestimated because this approach does not account for TA non-planarity, partially identifying RA walls as annular boundary, resulting in a minimum at ED, when the RA is smallest. Alternative software approaches that account for TA non-planarity should be explored with surgical validation and are required to accurately assess TA size and dynamics. This may have implications on TV annuloplasty planning.

Multi-Threaded Technology Apply in Real Time Measurement System of Dual-Camera

Based on multi-thread technology, completed a set of real-time dynamic measurement system apply on binocular vision principle. Real time measurement require of system efficiency higher, multithreaded programming can greatly improve the efficiency of program. Binocular dynamic real-time detection is based on closed-loop control system, puts forward a multithreaded programming technology which is based on the binocular vision high-speed dynamic measurement method. The data acquisition, processing, display are using multithreading technology.