Electromechanical Response of Smart Ultra-High Performance Concrete under External Loads Corresponding to Different Electrical Measurements

This study investigated the electromechanical response of smart ultra-high-performance concretes (smart UHPCs), containing fine steel slag aggregates (FSSAs) and steel fibers as functional fillers, under external loads corresponding to different measurement methods. Regardless of different measurement methods of electrical resistance, the smart UHPCs under compression showed a clear reduction in their electrical resistivity. However, under tension, their electrical resistivity measured from direct current (DC) measurement decreased, whereas that from alternating current (AC) measurement increased. This was because the electrical resistivity, from DC measurement, of smart UHPCs was primarily dependent on fiber crack bridging, whereas that from AC measurement was dependent on tunneling effects.

Digital fluxgate current sensor based on second harmonic detection

This paper presents a new digital fluxgate current sensor based on second harmonic detection for DC and AC measurement. The sensor utilizes a feedback loop to obtain an almost zero-flux condition, i.e., a balance between the magnetic flux of the primary current and the feedback current, in which way the feedback current is proportional to the primary current. The AC magnetic flux is detected with an induction coil, and the DC zero-flux condition is realized by magnetic saturation effect method, where the magnetic core is periodically magnetized and then the second harmonic of the magnetization current is calculated as an indication of the DC magnetic flux. After theoretical derivation, the operating principle of the sensor was investigated using a numerical simulation model built with Simulink of MATLAB. In addition, a prototype sensor was developed and tested. The experiment results demonstrate that the current sensor works properly for DC and AC measurement. The average error is about 0.06% for DC measurement.

The Relationship between Atherosclerosis and Non-Alcoholic Fatty Liver Disease According to Polysystemic Ultrasound of the Arteries and Hepatic Steatometry

Introduction. Coronary heart disease (CHD) remains the most common cause of death and disability in Ukraine and around the world. CHD is caused by atherosclerosis. Non-alcoholic fatty liver disease (NAFLD) is considered an independent predictor of CHD. Aim. To identify the relationship between atherosclerosis and NAFLD according to polysystemic ultrasound (ps-US) of the arteries and liver steatometry. Materials and methods. We conducted an open prospective study in 2019 of 93 people, including 58 women and 35 men aged 22 to 79 years. Chronic CHD was detected in 36 patients and 57 apparently healthy individuals. US was performed by Soneus P7 (Ultrasign, Ukraine). We determined condition of the abdominal organs in the B-mode as well as the amount extent of hepatic steatosis – through steatometry by attenuation coefficient (AC) measurement – ACM) for the diagnosis of NAFLD. Atherosclerosis of the abdominal aorta and common carotid arteries (atherosclerotic plaques and the thickness of the intima-media complex) was detected. Results and discussion. There was an increase in AC (a sign of NAFLD) in 36 patients with CHD. The presence of carotid atherosclerosis confirms a higher percentage of patients with signs of hepatosis in the CHD group. Conclusions. An innovative method of quantitative ultrasound of hepatosteatosis (steatometry) can be used as a screening for the detection of NAFLD in population studies. The relationship between markers of atherosclerosis and NAFLD has been revealed according to the data of ps-US of the arteries and hepatic steatometry which allows to prescribe comprehensive treatment and evaluate its effectiveness. NAFLD can be a predictor of atherosclerosis and the formation of CHD, which gives grounds for the primary prevention of the latter.

A New Logging-While-Drilling Method for Resistivity Measurement in Oil-Based Mud

Resistivity logging is an important technique for identifying and estimating reservoirs. Oil-based mud (OBM) can improve drilling efficiency and decrease operation risks, and has been widely used in the well logging field. However, the non-conductive OBM makes the traditional logging-while-drilling (LWD) method with low frequency ineffective. In this work, a new oil-based LWD method is proposed by combining the capacitively coupled contactless conductivity detection (C4D) technique and the inductive coupling principle. The C4D technique is to overcome the electrical insulation problem of the OBM and construct an effective alternating current (AC) measurement path. Based on the inductive coupling principle, an induced voltage can be formed to be the indirect excitation voltage of the AC measurement path. Based on the proposed method, a corresponding logging instrument is developed. Numerical simulation was carried out and results show that the logging instrument has good measurement accuracy, deep detection depth and high vertical resolution. Practical experiments were also carried out, including the resistance box experiment and the well logging experiment. The results of the resistance box experiment show that the logging instrument has good resistance measurement accuracy. Lastly, the results of the well logging experiment indicate that the logging instrument can accurately reflect the positions of different patterns on the wellbore of the experimental well. Both numerical simulation and practical experiments verify the feasibility and effectiveness of the new method.

Sources of error in AC measurement of skin conductance

Alternating current methods have the potential to improve the measurement of electrodermal activity. However, there are pitfalls that should be avoided in order to perform these measurements in a correct manner. In this paper, we address issues like the choice of measurement frequency, placement of electrodes and the kind of electrodes used. Ignoring these factors may result in loss of measurement sensitivity or erroneous measurements with artifacts that contain little or no physiological information.

Some Features of the Calibration Equipment for Measuring the Parameters of Impedance

Peculiarities of the accurate impedance meters calibration are considered. Author show that most important and complicate part of calibration procedure consists in determination of two uncertainty components: additive error and error, caused by nonlinearity of the meter transfer function. Problems of the determination of the additive error are caused by the fact, that there no exist accurate standard of the zero impedance. Author considers the creation of proper zero impedance standard, whose impedance can be arbitrarily close to zero and its impedance remnant can be estimated on the base of its geometrical dimensions. Implementation of such standard is very simple, cheap, and easily carried out. This standard works well on DC. Standard of zero impedance for AC measurement consists of two coaxial T-branches, which are connected through insertion piece. Such standard eliminates influence of the possible mutual inductive connection between current and voltage loops of the proper cables, which connect the “zero impedance standard” and measuring devise. To determine nonlinearity of the transfer function author analyze using of the non accurate resistive or alternative impedance dividers. To use such dividers in whole range of measurements special structures of these dividers where developed. In these structures measurement of the divider standards are provided together with impedance of their terminals. It eliminates influence of the impedance of these terminals on the accuracy of meter calibration or unit transfer. Special complex of two-standards dividers were developed to simplify the accurate calibration of the impedance meters.