Use of statistical analysis methods in processing population survey data

The article analyzes the structures of the measuring channels of electricity metering systems. It is shown that such a structure is determined by the types of measuring instruments used and the scheme of their connection, in particular, by the types of electricity meters installed at the metering points. Moreover, the counters can have a pulse or interface information output. It is shown that the path for measuring and metering electricity includes a measuring circuit consisting of measuring current and voltage transformers, an electricity meter, communication lines, a metering device and a data collection device. The applied method is based on the standardization of the metrological characteristics of individual elements of the measuring path and their synthesis based on the metrological characteristics of the entire electricity metering system. To calculate the total error of the measuring channel, a formula is used that takes into account only the errors of the measuring circuit. It is shown that in recent years there has been a tendency when measuring current transformers and, accordingly, electricity meters operate in the mode of low current loads. In this case, the errors of the elements of the measuring path are poorly studied. The graphs of errors of current transformers depending on load currents are given. It is shown that the values of the errors of current transformers vary with the magnitude of the load current and are in the region of negative values. Therefore, the wrong choice of current transformers can lead to a significant underestimation of electricity. The errors of voltage transformers depend mainly on the load on the secondary winding and do not significantly affect the total error. The resulting error of the measuring path current transformer - voltage transformer - electricity meter in the area of low loads is given. A change in errors in the area of low loads leads to serious metrological losses (underpayment of electricity). In the automation of electricity metering, graphs of changes in errors in the area of low loads are presented, which can serve as a basis for correcting the error of the measuring paths.

A Novel Sensor for In Situ Detection of Freeze-Thaw Characteristics in Plants from Stem Temperature and Water Content Measurements

Freezing is a typical abiotic stress on plants, which can induce physiological damages of plants. A better understanding of plant freeze-thaw characteristics contributes to solving some hot issues in plant physiology, such as cold resistance and cold acclimation. This article presents a novel sensor for in situ detection of freeze-thaw characteristics in plants based on stem temperature and water content. The measuring circuit of stem temperature was designed based on constant current source and platinum resistance. The measuring circuit of stem water content was designed based on standing wave ratio and the dielectric properties of stem tissue. The temperature resolution of the compound sensor is less than 0.1°C. The MAE and RMSE of temperature measurement are approximately 0.57°C and 0.65°C, respectively. The volumetric water content resolution of the compound sensor is less than 0.05%. The MAE and RMSE of volumetric water content measurement are approximately 1.59% and 1.81%, respectively. Moreover, a mathematical model for describing the freeze-thaw characteristics of plant stem was established and solved based on the compound sensor. Then, some freeze-thaw indicators including stem water content, ice content, freezing depth, freezing velocity, thawing depth, and thawing velocity were solved and used to interpret the freeze-thaw rules of plant stem. It can be concluded that the freeze-thaw velocity is closely related to the physicochemical properties of plant stem which also change dynamically in the freeze-thaw cycle.

Concepção de um sistema de automação e monitoramento para equipamento utilizado em ensaios de trilhamento elétrico e erosão

<p>This paper aimed at the design and development of a data acquisition and control system using the Arduino open-source platform to automate equipment responsible for the IEC 60587 electrical tracking and erosion test. The developed system allows the selection of protection resistors specified by the standard from the voltage value informed by the operator, monitoring of the leakage current flowing over five samples simultaneously tested and automatically interrupts the samples if the leakage current exceeds 60 mA for more than two seconds. The leakage current values are measured indirectly from the voltage drop across 50 Ω shunt resistors installed in series with each sample. The voltage values on the shunt resistors are conditioned by a measuring circuit that allows the voltage level to be adjusted to the analog inputs of the microcontroller, ie, between 0 V and 5 V. The microcontroller treatment performs the voltage signal obtained by the measuring circuit, the calculation of the RMS value of the current and stop criterion monitoring the leakage current. The calibration of the leakage current measurement circuit was performed by comparing voltage values measured by a digital oscilloscope for four different alternate waveforms and values up to 5 Vrms, corresponding to currents up to 100 mA. The results showed that the circuit provided measurements close to the values measured by the oscilloscope, with errors below 11%. For current values between 30 mA and 80 mA, the errors were less than 6%.</p>

Features of circuitry of acousto-optic laser measuring systems for controlling three-coordinate (3D) movements of products and equipment elements. Part 1

The article is devoted to the construction of acousto-optic (AO) laser measuring systems (LMS) for measuring product displacements in three coordinates (3D): with one longitudinal Δl z and two transverse Δl x , Δl y with high resolution and an increased measurement range for the latter two. The paper discusses the circuitry of the measuring circuit based on the phase-locked loop (PLL) system, which makes it possible to achieve the maximum resolution when the AO LMS operates in the start-stop mode, i.e. starting and ending with a stationary state at v=0. The paper considers the possibilities of using a prismatic optical scheme, which makes it possible to use a one-axis (1D) AO modulator to control two-coordinate (2D) displacements Δl x , Δl y of a laser beam, a multi-aperture AO modulator, a fiber photodetector and other units