Abstract
The accuracy of DC measurement system directly affects the reliable operation of DC control and protection system. In order to improve the estimation and prediction of DC measurement system ...op-eration state, a trend prediction algorithm based on multi-dimensional analysis and long-term memory network is proposed. Based on the analysis of DC measurement principle, the DC measurement status is diagnosed and abnormal is identified by time series trend analysis and anomaly detection. The LSTM is used to construct a multi factor driving current prediction model, and the model is trained and an-alyzed based on the actual operation data. Compared with the traditional time series prediction model, the results indicate that the proposed method is more accurate, simple and effective, and can be applied to the prediction of driving current.
In order to raise the accuracy of the circular gratings angle-measuring system, a comprehensive error model is established, and a novel compensation method is proposed. Firstly, many error sources, ...including the rotary errors of axis system, the installation eccentricity and the inclination of the circular grating disc, the graduation line error of the circular grating disc, and the installation error of the multiple readingheads of the high precision circular gratings angle-measuring system are comprehensively taken into consideration. Secondly, the position and attitude errors are propagated to the angular position outputs, thus the mathematical relationships between error sources and the angular position error are established. Aiming at multiple readingheads system, the mechanism of influence of the error sources on the angular position error is unveiled, and the mechanical error identification and reduction method is proposed. After that, a checking system with a 23-mirrored polygon and an autocollimator is set up, and the complete combinatorial method of separating the angular position errors from the readouts of the autocollimator precisely is used. Finally, the angular position error compositions are separated by the harmonic analysis method, and the concerned error coefficients are compensated. The experimental results show that the nominal indication interval value of the angular position errors is reduced to 0.23" by the mechanical error reduction method, and then the nominal indication interval value of the angular position errors is reduced to 0.12" by software measurement method. And the two sets’ repeatability of the separated biases of the 23-mirrored polygon before and after compensating is 95%.
Display omitted
•An error model designed includes all error sources in angle-measuring system.•Radial error, eccentricity errors and indicating grating installing errors can be reduced.•Mechanical compensation method and software compensation method are combined to further improve angle measurement system accuracy.•Consistency of polygon separated biases in different initial angular position validates the effectiveness.•Proposed method is suitable for any angle measurement system.
Today's stamping simulations are realized by ignoring the elastic deformation of the press and tooling system through the assumption of a rigid behavior and a perfect press stroke. However, in ...reality, the press and tool components deform elastically and are one of the major error sources for the final adjustment and blue-spotting of the dies. In order to tackle this issue, a new approach is proposed in this study that substitutes the press stiffness by means of a substitutive model composed of cost-effective shell and beam elements. The substitute model was calibrated using full-scale measurements, in which a 20,000 kN trial press was experimentally characterized by measuring its deformation under static loads. To examine the robustness of the substitute model, a medium-size tool and a large-size tool were simulated together with the substitutive model. To this end, a B-pillar tool was re-machined based on the substitute-model results and a new cambering procedure was proposed and validated throughout the blue-painting procedure. The newly developed substitute model was able to replicate the global stiffness of the press with a high accuracy and affordable calculation time. The implementation of the findings can aid toolmakers in eliminating most of the reworking and home-line trials.
High shrinkage of tile adhesive is believed to be a technological flaw, leading to the risk of faulty tile fixing. As in real‐life conditions, there is a very limited possibility of mortar movement ...under tile, the shrinkage/expansion‐induced stress could be created, which needs to be absorbed by the mortar. The significance of the problem increases with the tile size. On contrary, the length changes of such materials are usually measured on the prisms which reflects neither the application thickness nor the real‐life curing conditions of the mortar.
In this paper, we are aiming to measure tile adhesives' length change potential in simulated real‐life conditions. The test set‐up involves a Thin‐Layer‐Shrinkage‐Measuring‐System allowing for the examination of flat rectangular samples of 350x350 mm in size and several millimeters of thickness. Dimensional changes were measured in situ by the laser sensors. Additionally, the weight changes were monitored over the whole measurement. The obtained results were juxtaposed with the shrinkage measured on the prisms.
The paper provides valuable insights into the dimensional changes of tile adhesives in real‐life applications. Obtained results challenge the conventional measurements done on prisms stored in ambient conditions.
In this article, the design and development aspects of a compact bio-potential measuring system, named ExGSense, is presented. Two versions of the prototype have been developed; first one can measure ...3 + 1 V leads in time-multiplexed fashion, while the other can measure 3 + 1 V leads simultaneously. This article also presents an efficient algorithm for filtering electrocardiogram signals which is required to attenuate the effect of motion artefacts which are inevitable in wearable systems. Further, a user-friendly interface for PC and smartphone has also been developed. By the virtue of an ultra-low noise instrumentation amplifier and the programmability of gain and bandwidth of the bio-signal measuring system, a number of other bio-potential signals like EMG, EOG and EEG have been successfully recorded using disposable, off-the-shelf wet Ag/AgCl electrodes.
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