Measuring scheme for determination of loads acting on the side frame of the bogie from a wheelset

The study aims to develop a measuring circuit to determine the loads acting on the side frame of the bogie from the wheelset when the wagon is moving. The paper reviews and analyzes experimental methods for measuring the vertical and lateral forces acting on the side frame of the bogie from the wheelset when the wagon is moving. Theoretical studies of the stress-strain state of the side frame of a freight wagon bogie were carried out using the finite element method under the action of loads on the axle opening from the wheelset. As a result of theoretical studies by the finite element method, the places for the installation of strain gauges were determined, and a method for processing the received signals was selected. The developed measuring scheme makes it possible to determine the spatial force effect acting on the side frame of the bogie from the wheelset, which makes it possible, without increasing the number of measuring channels in the equipment, to reduce the number of strain gauges for measuring the considered loads while running dynamic tests. In addition, it improves the accuracy of measurements of vertical loads, with the help of which the coefficient of dynamic addition of unsprung parts of the bogie is calculated.

The optical frequency standard based on strontium cold atoms

The results obtained during the development of an optical frequency standard, based on cold 87Sr atoms are presented. The parameters of experimental optical schemes developed for the realization of all stages of sequential laser cooling and trapping of 87Sr atoms into an optical lattice are described. Clock transition spectroscopy was successfully performed with a spectral transition linewidth of 12 Hz. A measuring scheme based on a femtosecond optical frequency synthesizer has been developed, which makes it possible to compare the optical standard with a hydrogen maser. The created optical frequency standard was included in the primary standard GET 1-2018.

Application of DMA 242 C for Quasi-Static Measurements of Piezoelectric Properties of Solids

An experimental device for quasi-static measurements of piezoelectric moduli dijk, based on the possibilities of precision variations in mechanical stresses with the device DMA 242 C in the frequency range 0-100 Hz has been developed. A special sample holder and a charge amplifier are used in the measuring scheme. The measurements of piezoelectric moduli values of trigonal piezoelectric single crystalls La3Ga5SiO14 (P321) and YAl3(BO3)4 (R32), as well as hexagonal ZnO (P63mc) have been carried out

Impact of underground cables on ground impedance measurement implementing FSM concept in FOP measuring scheme

Ground impedance measurement in medium voltage substations, designed to operate in a predominantly cable network, is a complex research task. Namely, the inability to consider all the factors that can affect the measured value, in a situation where one deenergized cable line is used to form the Fall-of-Potential (FOP) measurement scheme, is directly reflected to an adequate assessment of safety risks. This paper proposes an alternative measurement method so called Frequency Shift Method (FSM), which inherently guarantees "better" measurement than any of the conventional methods. By providing insight into the behavior of the active and reactive ground impedance components, and at the same time taking into account the topological structure of the existing cable network, the application of the FSM concept in the FOP measurement scheme points out to alternative paths of test current distribution, and in that way pointing to the illogicality of the obtained measurement results. Experimental verification was conducted under real operating conditions, and can serve as a guide for solving similar problems in practice.

Design and Implementation of a Novel Measuring Scheme for Fiber Interferometer Based Sensors

This paper presents a novel measuring scheme for fiber interferometer (FI) based sensors. With the advantages of being small sizes, having high sensitivity, a simple structure, good durability, being easy to integrate fiber optic communication and having immunity to electromagnetic interference (EMI), FI based sensing devices are suitable for monitoring remote system states or variations in physical parameters. However, the sensing mechanism for the interference spectrum shift of FI based sensors requires expensive equipment, such as a broadband light source (BLS) and an optical spectrum analyzer (OSA). This has strongly handicapped their wide application in practice. To solve this problem, we have, for the first time, proposed a smart measuring scheme, in which a commercial laser diode (LD) and a photodetector (PD) are used to detect the equivalent changes of optical power corresponding to the variation in measuring parameters, and a signal processing system is used to analyze the optical power changes and to determine the spectrum shifts. To demonstrate the proposed scheme, a sensing device on polymer microcavity fiber Fizeau interferometer (PMCFFI) is taken as an example for constructing a measuring system capable of long-distance monitoring of the temperature and relative humidity. In this paper, theoretical analysis and fundamental tests have been carried out. Typical results are presented to verify the feasibility and effectiveness of the proposed measuring scheme, smartly converting the interference spectrum shifts of an FI sensing device into the corresponding variations of voltage signals. With many attractive features, e.g., simplicity, low cost, and reliable remote-monitoring, the proposed scheme is very suitable for practical applications.

Disposable Potentiometric Sensory System for Skin Antioxidant Activity Evaluation

The skin is a natural barrier between the external and internal environment. Its protective functions and the relationship of its state with the state of health of the organism as a whole are very important. It is known that oxidant stress (OS) is a common indicator of health status. This paper describes a new sensory system for monitoring OS of the skin using antioxidant activity (AOA) as its criteria. The contact hybrid potentiometric method (CHPM) and new electrochemical measuring scheme were used. A new sensory system, including disposable modified screen-printed carbon and silver electrodes covered by membrane impregnated by mediator, was developed. Its informative ability was demonstrated in the evaluation of the impact of fasting, consumption of food and food enriched by vitamins (antioxidants) on skin AOA. This device consisting of a sensory system and potentiometric analyzer can be used in on-site and in situ formats.

A Novel Unique Parameter for Increasing of Security in GPON Networks

Passive optical networks are widely used because of their sufficient bandwidth and low price of individual elements.Based on the European Commission, The Czech Republic ISPs have to ensure 30 Mbit/s (in existing networks) and 100 Mbit/s (in new constructed networks) for each customer in selected areas till 2020. Nowadays, the GPON standard is dominating in the Europe due to its low price and maturity. In general, the passive optical networks are based on P2MP (Point to Multipoint) physical topology. Therefore each end unit receives data meant for all units. To mitigate this, the standard defines an encryption method (authentication and key exchange phase) but the key exchange phase relies only on a single unique parameter (serial number of an end unit). A new unique parameter for the key exchange phase is proposed. No modification of the transmission convergence layer in GPON is considered. A measuring scheme for determining of accuracy of our new unique parameter, called Tprop, is also proposed.