This work presents the design, fabrication, and characterization of a novel microwave-based sensor utilizing multiple U-shaped resonators for non-contact measurement of volume percentages in water-crude oil mixtures. The sensor, fabricated on an RT/Duroid 4003 substrate (Sr = 3.55, thickness 0.787 mm), operates in the 2-2.3 GHz frequency range with a maximum insertion loss of 0.97 dB. Design optimization and electromagnetic simulations were performed using ADS software followed by experimental validation with 10 ml samples of varying water content (0-100%) placed in a 3D-printed PLA container. Significant shifts in center frequency and response prominence were observed, enabling clear differentiation of mixture compositions. The sensor achieved a high sensitivity of 4.12 MHz/Sr, surpassing many prior designs, while the non-contact configuration enhances practicality by minimizing contamination risks and interference. Although highly sensitive and compact, potential limitations include dependence on crude oil composition variability, temperature effects, and the fixed sample volume used in testing. These results demonstrate the sensor's reliability for real-time fluid analysis, with promising applications in petroleum, chemical, and environmental monitoring industries.
Image intensifier tube is the most important block of night vision devices that enable vision at low illumination conditions and are of critical importance for military and security agencies. SNR (signal to noise ratio) is one of two most important parameters of image intensifier tubes. This paper presents a review of methods used to measure the SNR of image intensifier tubes. Reasons why SNR test results of the same tube carried out by different laboratories often differ significantly are presented.
The precision rotary table is an angular positioning generator commonly used in the industry. Ensuring its long-term stability of positioning accuracy is a key concern. Researchers have conducted extensive studies on the online calibration and real-time compensation of rotary table positioning errors. However, existing research often involves some offline processing throughout the calibration and compensation stages. Currently, there is very little research on methods in which the entire process of calibrating and compensating rotary table positioning errors is fully online. Therefore, this paper proposes a fully online calibration-compensation method for rotary table positioning errors and develops a rotary table positioning error calibration-compensation system. Based on the Fourier self-calibration principle and the harmonic compensation principle, this method implements online calibration and real-time compensation of positioning errors using a heterogeneous processor. Throughout the entre process, data processing is guaranteed to be online. The experimental results show that the positioning accuracy of the rotary table improved from [-150.0 '', 137.9 ''] to [-1.3 '', 1.6 ''], effectively improving its precision. The proposed method is highly suitable for compact or cost-sensitive precision rotary tables, while also being applicable for spindle condition monitoring.
Wayside measurements by means of a strain gauge placed on rails are an important test method to measure the wheel-rail contact forces that determine the safety of rail vehicles traveling on the track. In this method, to enhance the reliability of the monitoring results, strain gauge sections and measurement equipment should be calibrated under operating conditions. In this study, a design of a device has been developed for the calibration of strain gauges used in wayside measurement techniques. The systematic approach proposed by Pahl and Beitz and further developed by Feldhusen and Grote was utilised in the design process. With this innovative design, a safe, simple, compact, and user-friendly device capable of applying both vertical and horizontal forces with a single unit has been developed.
The article presents an analysis of a three-phase electric circuit in terms of describing the power components measured and determined on a three-wire line connecting an unbalanced power source with periodic, non-sinusoidal waveforms with an unbalanced receiver. In this study, the case was considered when the load admittance changes its value when the direction of rotation of the symmetrical voltage and current components is changed. This is a typical situation where three-phase power must be measured on a three-wire line connecting a real source to a load that contains three-phase rotating machines. In real systems, such machines often change their current/voltage relationship when the direction of rotation changes. This paper presents a modification of the currents’ physical components (CPC) power theory to decompose currents and powers into symmetrical components. This constitutes the theoretical framework of this study. Using the determined dependencies, it is possible to develop a new measurement algorithm. As a result of these measurements, it is possible to determine the electromechanical efficiency of the rotating machine, i.e., the efficiency that does not take into account the influence of higher harmonics and power source asymmetry. This is important information needed to optimise the active power consumption of electromechanical machines. Measurement of active power using classical methods does not allow one to observe the influence of supply voltage asymmetry on the power that affects active conversion to mechanical power. Thanks to such measurements, it is possible to select optimal parameters of the electric motor in order to improve the efficiency of converting electrical energy into mechanical energy. In this approach, the asymmetry of the power supply and the introduction of higher voltage harmonics are perceived as external interferences in the optimisation process. This fragment of the article constitutes the practical side, i.e. the application of the theoretical considerations derived. In the presented calculation example, it was shown that the efficiency of the machine strongly depends on the asymmetry of the voltage source, and less on the harmonics.
