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"Electric measurements."
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Eliminating Ambiguities in Electrical Measurements of Advanced Liquid Crystal Materials
Existing and future display and non-display applications of thermotropic liquid crystals rely on the development of new mesogenic materials. Electrical measurements of such materials determine their suitability for a specific application. In the case of molecular liquid crystals, their direct current (DC) electrical conductivity is caused by inorganic and/or organic ions typically present in small quantities even in highly purified materials. Important information about ions in liquid crystals can be obtained by measuring their DC electrical conductivity. Available experimental reports indicate that evaluation of the DC electrical conductivity of liquid crystals is a very non-trivial task as there are many ambiguities. In this paper, we discuss how to eliminate ambiguities in electrical measurements of liquid crystals by considering interactions between ions and substrates of a liquid crystal cell. In addition, we analyze factors affecting a proper evaluation of DC electrical conductivity of advanced multifunctional materials composed of liquid crystals and nanoparticles.
Journal Article
Electrical Measurement Dataset from a University Laboratory for Smart Energy Applications
Continuous monitoring of electrical parameters is essential for understanding energy consumption, assessing power quality, and analyzing load behavior. This paper presents a dataset comprising measurements of three-phase voltages and currents, active and reactive power (per phase and total), power factor, and system frequency. The data was collected between April and December 2024 in the low-voltage system of a university laboratory, using high-accuracy power analyzers installed at the point of common coupling. Measurements were recorded every 10 min, generating 79 files with 432 records each, for a total of approximately 34,128 entries. To ensure data quality, the values were validated, erroneous entries removed, and consistency verified using power triangle relationships. The curated dataset is provided in tabular (CSV) format, with each record including a timestamp, three-phase voltages, three-phase currents, active and reactive power (per phase and total), power factor (per phase and global), and system frequency. This dataset offers a comprehensive characterization of electrical behavior in a university laboratory over a nine-month period. It is openly available for reuse and can support research in power system analysis, renewable energy integration, demand forecasting, energy efficiency, and the development of machine learning models for smart energy applications.
Journal Article
Enhanced impedance, electrical conductivity, dielectric properties for colloidal starch-g-poly (methyl methacrylate) supported with semiconductor cadmium sulfide
In this study, starch-graft-poly (methyl methacrylate) (starch-g-PMMA) composites doped with different amounts (5, 10, and 15 wt%) of cadmium sulfide (CdS) particles were fabricated for electrical measurements using in-situ polymerization technique. The structural characterization of the samples was studied. The dielectric and conductivity properties of the composites were investigated using impedance analyzer depending on the frequency (100 Hz–20 kHz) at room temperature. Spectroscopy revealed that the dielectric constant (
ε
′), dielectric loss (
ε
′′), and real (
Z
) components of impedance are found to decrease with increasing frequency for both starch-g-PMMA and starch-g-PMMA (5, 10, and 15 wt%) composites. On the contrary, the AC conductivity (
σ
ac
) of samples increased with increasing frequency. In addition,
ε
′ and
ε
′′ values of starch-g-PMMA were lower than composites that added CdS. When the CdS content increased from 0 to 15%,
ε
′ increased from 5.62 to 15.10 at 100 Hz. AC conductivity was improved after adding the CdS particles. The maximum conductivity value for starch-g-PMMA
15%CdS
is found to be 3.07 × 10
–7
at 100 Hz. When the dielectric properties of composites are evaluated, it is concluded that it is an exciting material for electronic applications in technology.
Journal Article
Experimental Examination of Electrical Characteristics for Portland Cement Mortar Frost Damage Evaluation
Electrical measurements are promising for evaluation of frost damage of concrete, but the index is still controversial. In this paper, to propose an efficient index, various electrical characteristics were examined to correlate them with the mechanical property degradation of meso-scale mortar samples due to combined effects of sodium chloride and freeze–thaw cycles (FTCs). While the electrical responses of specimens were measured during FTCs, the mechanical properties were obtained from three-point bending tests after FTCs. Typical microstructural change after the damage was also analyzed by using a water absorption test. The results showed that no clear degradation tendency was observed for electrical resistivity at the lowest temperature, the activation energy or the freezing/thawing point change with the FTCs. The reduction in electrical resistivity at reference temperature has a consistent tendency with that of elastic modulus and flexural strength, thus can be an efficient index for quantitative frost damage evaluation. The change due to salt-frost damage is mainly due to the increase of connectivity rather than porosity.
Journal Article
Current and voltage based bit errors and their combined mitigation for the Kirchhoff-law–Johnson-noise secure key exchange
We classify and analyze bit errors in the current measurement mode of the Kirchhoff-law–Johnson-noise (KLJN) key distribution. The error probability decays exponentially with increasing bit exchange period and fixed bandwidth, which is similar to the error probability decay in the voltage measurement mode. We also analyze the combination of voltage and current modes for error removal. In this combination method, the error probability is still an exponential function that decays with the duration of the bit exchange period, but it has superior fidelity to the former schemes.
Journal Article
Electrical conductivity measurement in Thiel-embalmed tissue model: relevance to radiofrequency ablation
Thiel-embalmed human cadaveric specimens are used widely for biomedical scientific investigation. This Letter reports electrical impedance measurements of Thiel-embalming solutions from 1 Hz to 32 MHz. Compared with other solutions studied, Thiel solution has the lowest impedance throughout the test spectrum. The electrical conductivity of a Thiel-embalmed liver sample exhibited a relatively flat frequency response from 100 to 500 kHz, which is the frequency range used for electro-surgery and radiofrequency tumour ablation (RFA). It measured 5 Sm−1 compared with 0.22 Sm−1 obtained from ex-vivo fresh pig liver. Using finite element modelling and experimental evaluation, the ablation zone obtained from the Thiel-embalmed liver sample was extremely small due to its much higher conductivity. Hence, it is concluded that Thiel-embalmed tissue cannot be used as a reliable model for RFA evaluation.
Journal Article
Influence of raw carbon nanotubes diameter for the optimization of the load composition ratio in epoxy amperometric composite sensors
In this work, it is reported the necessity to characterize the raw carbon materials before their application in composite electrodes based on multiwall carbon nanotubes (MWCNTs) dispersed in epoxy resin for the development of improved amperometric sensors. These sensors must contain an optimum MWCNT/epoxy ratio for their best electroanalytical response. The main drawback in MWCNTs composite materials resides in the lack of homogeneity of the different commercial nanotubes largely due to different impurities content, as well as dispersion in their diameter/length ratio and state of aggregation. The optimal composite electrode composition takes into account the high electrode sensitivity, low limit of detection, fast response, and electroanalytical reproducibility. These features depend on carbon nanotube physical properties as the diameter. Three different commercial carbon nanotubes with different diameters were characterized by transmission electron microscopy and the results were significantly different from the ones provided by the manufacturers. Then, the three MWCNTs were used for the MWCNT/epoxy sensors construction. After an accurate electrochemical characterization by cyclic voltammetry and electrochemical impedance spectroscopy, they were employed as working electrodes using ascorbic acid as a reference analyte. Percolation theory was applied in order to verify the electrochemical results. It is demonstrated that the optimum interval load of raw carbon material in the optimized-composite electrodes closely depends on the MWCNTs diameter, needing 5 % in carbon content for the narrowest MWCNTs containing composite electrodes versus 12 % for the widest MWCNTs.
Journal Article
Development and Application of an Open Power Meter Suitable for NILM
In the context of the global energy sector’s increasing reliance on fossil fuels and escalating environmental concerns, there is an urgent need for advancements in energy monitoring and optimization. Addressing this challenge, the present study introduces the Open Multi Power Meter, a novel open hardware solution designed for efficient and precise electrical measurements. This device is engineered around a single microcontroller architecture, featuring a comprehensive suite of measurement modules interconnected via an RS485 bus, which ensures high accuracy and scalability. A significant aspect of this development is the integration with the Non-Intrusive Load Monitoring Toolkit, which utilizes advanced algorithms for energy disaggregation, including Combinatorial Optimization and the Finite Hidden Markov Model. Comparative analyses were performed using public datasets alongside commercial and open hardware monitors to validate the design and capabilities of this device. These studies demonstrate the device’s notable effectiveness, characterized by its simplicity, flexibility, and adaptability in various energy monitoring scenarios. The introduction of this cost-effective and scalable tool marks a contribution to the field of energy research, enhancing energy efficiency practices. This research provides a practical solution for energy management and opens advancements in the field, highlighting its potential impact on academic research and real-world applications.
Journal Article