Dynamic Correction of the Influence of Long Measuring Path Irregularity in Antenna Tests

This article investigates the influence of random microwave discontinuities on the characteristics of long transmission paths. This is most important for dynamic measuring stands, accompanied by multiple space movement of long transmission paths with their bending or twisting during the measurement process. In modern active electronically scanned arrays this issue also becomes relevant, due to increased requirements for the accuracy of beam shaping. The aim of this study is to develop a theoretical background and perform experimental verification for taking into account the effect of random microwave discontinuities on the transmission path characteristics. A method for correcting the effect of such irregularities is considered based on electrical length control by measuring the input reflection coefficient. Relations for the magnitude and phase of the path’s input reflection coefficient depending on the S-parameters of a long four-terminal network terminated with mismatched load are obtained and plotted. Using theory of sensitivity, the mathematical expressions of conditions were obtained to achieve maximum accuracy of measuring the electrical length of a long microwave path. The possibility of dynamic error correction in antenna measurements with a long test path caused by random microwave irregularities along it has been experimentally proved.

Nonlinearity Correction in Dynamic Measuring Devices Using Neural Network Models

A neural network compensator for the nonlinearity of a dynamic measuring instrument is proposed, which allows restoring the value of the measured input signal. The inverse model of a nonlinear dynamic measuring device is implemented based on a three-layer perceptron supplemented by delay lines of input signals. The properties of the proposed neural network compensator are studied through simulation computer modelling using various types of calibration input signals for the training of an artificial neural network.

Study on Secondary Cable Adjustment for Cable-stayed Bridges Without back Cables

<p>The structure of cable-stayed bridge without back cable is a new breakthrough.In this paper, the cable adjustment process of linzhou yingbin bridge is studied. the whole bridge model is established using the finite element software MIDAS CIVIL.This paper compares the measured cable force with the designed cable force and gets range of cable force difference, The influence matrix method is used for the second cable adjustment to ensure that the stress and structural deformation in the process of cable adjustment are within the range of the design requirements.The cable force variation of the whole bridge is detected by dynamic measuring instrument to ensure the construction safety in the process of cable adjustment.</p><p> </p>

Replacing the observed object in a dynamic measuring system

In this article the problem of an object state vector estimation is considered. This estimation is obtained by the treatment of measured parameters from several observed objects. In our case, we have two measured parameters that change their values over a certain time interval, but only one of them can be measured at each moment. The problem is to find the moment for switching the measurement from one object to another one in order to minimize the dispersion of one component of the state estimation vector. Previously, the Elfing problem was solved to repeatedly measure fixed parameters using this data in proportion to weight coefficients for processing with the least square method. Then, to change the measured values, a transfer from the discrete model to the continuous one was proposed. This made it possible to obtain an analytical expression dispersion that was dependent of the time moment on the switching. In this article, the estimation of the continuous model error is conducted and the sufficient conditions of using no more than one switching are proven. An example of this method’s application is shown to estimate the sea object coordinates using navigation satellites.

Model for Predicting Road Markings Service Life

Road markings provide drivers with the information necessary for their comfortable and safe journey. To achieve that, they must be visible in all driving conditions, which means that they have to be renewed and maintained in a timely manner. This research aims to develop a model for predicting the service life of paint, thermoplastic and agglomerate cold plastic road markings. The research comprised 5218.00 km (115 roads) of solvent-borne paint road markings, 579.00 km (30 roads) of thermoplastic and 4979.00 km (30 roads) of agglomerate cold plastic road markings. The retroreflectivity of road markings was measured two times (after renewal and after winter) using the dynamic measuring method. Service life prediction model was developed for each material based on factors such as initial retroreflectivity, road marking age and position, annual average daily traffic and winter maintenance activity of the road. Developed models were tested using a new data set, and all three models showed satisfactory accuracy. The application of the model enables road authorities to optimise road-marking maintenance activities, while at the same time, ensuring the level of visibility required by drivers.

Dynamic measuring methods: a review

The paper presents an overview of the directions in the development of dynamic measurement methods. First, the concept of dynamic measurements and a short historical background are outlined. The author describes several types of dynamic characteristics of measuring equipment, which fully characterise their dynamic properties. The next part is devoted to an analysis of the types of dynamic errors and their corrections. In conclusion, an overview of the identification of dynamic characteristics is given.

Determining the correlation between daytime and night-time road markings visibility

Road markings quality control implies conducting several different tests, of which the most significant are visibility tests comprising daytime and night-time visibility measurements by applying the static or the dynamic measuring method. Although the dynamic test method allows measuring the visibility along the entire road section and thus provides a more complete and objective evaluation of road markings quality compared to the static method, it does not measure daytime visibility, for which both the European and the national directives define the minimum requirements. The purpose of this paper is to examine the correlation between daytime and night-time visibility based on static measurements conducted on state roads in the Republic of Croatia. The correlation analysis determined that the strength of relationship between daytime and night-time visibility, is relatively weak. Despite being relatively weak, the relationship still exists, which was the reason for conducting a further analysis. In the analysis, a unique coefficient was obtained through the ratio of retroreflection value and daytime visibility value for all the measurements. The unique coefficient was basis for development of a model that will be able to calculate the daytime visibility based on the results of the dynamic measurements of road markings night-time visibility. The authors evaluated the model with a t-test and concluded that the accuracy of the model is statistically satisfactory.

Analysis of the Natural Frequencies of a Plexiglass Plate

In this article we verified the methodology of experimental measurements on plexiglass plate. We compared the natural frequencies of plate. The experiment was done under laboratory conditions using a portable dynamic measuring apparatus. We compared the experimental results with the results from software ANSYS based on finite element method.