Approximate Calculation Research Articles

Breakdown Voltage Estimation in Transformer Oils with Low-Cost Humidity Sensor

The relative humidity and temperature of the oil used for insulation purposes in transformers directly affect the breakdown voltage of the oil and accordingly the life of the transformer. Continuous monitoring of the moisture content and breakdown voltage of the transformer oil provides the basis for predictive maintenance practices. This study aims to develop a sensor to continuously monitor the moisture content of the insulating oil and to calculate the breakdown voltage approximately. In this context, firstly, measurements were taken with an industrial oil monitoring sensor which calculates the breakdown voltage in transformer oils with high accuracy and was verified with laboratory measurements. At the same time, EE364 by E+E™ and SHT10 by Sensirion™ also used for temperature and humidity measurements. By comparing the measured data with each other, a relationship was formulated between the humidity and temperature values and the breakdown voltage. As a result, an approximate breakdown voltage calculation method that can be used considering the characteristic parameters of transformer oil has been introduced. Thus, a cost-effective function has been developed that can be widely used for transformer monitoring systems.

Crossover in densities of confined particles with finite range of interaction

We study a one-dimensional classical system of N particles confined within a harmonic trap. Interactions among these particles are dictated by a pairwise potential V(x), where x is the separation between two particles. Each particle can interact with a maximum of d neighbouring particles on either side (left or right), if available. By adjusting the parameter d, the system can be made nearest neighbour (d=1) to all-to-all (d=N−1) interacting. As suggested by prior studies, the equilibrium density profile of these particles is expected to undergo shape variations as d is changed. In this paper, we investigate this crossover by tuning the parameter f(=d/N) from 1 to 0 in the large N limit for two distinct choices of interaction potentials, V(x)=−|x| and V(x)=−log⁡(|x|) which correspond to 1d one-component plasma and the log-gas model, respectively. For both models, the system size scaling of the density profile for fixed f turns out to be the same as in their respective all-to-all case. However, the scaling function exhibits diverse shapes as f varies. We explicitly compute the average density profile for any f∈(0,1] in the 1d plasma model, while for the log-gas model, we provide approximate calculations for large (close to 1) and small (close to 0) f. Additionally, we present simulation results to numerically demonstrate the crossover and compare these findings with our theoretical results.

Exact and efficient wall distance pre-classification overset grid assembly for unstructured grids

In this paper, we present a pre-classification overset grid assembly (OGA) based on the wall distance criterion. In contrast to the conventional OGA, where donor search is preceded by point classification, the proposed methodology first performs point classification based on the wall distance criterion, and then performs donor search on the reduced set of cells. To robustly profile the given grid components, a wall distance evaluation is performed exactly by considering the full geometry of the discretized surface while maintaining efficiency. The efficiency of the algorithm is achieved by redefining the methodology into a bounded form and establishing a conservative correlation between the vertex-based and element-based distances through a rigorous examination of geometric relations. From these observations, wall distance calculation, which requires a tremendous amount of computation, is divided into sequential steps of vertex-based approximate calculation and element-based exact calculation, dramatically reducing the computation load. To better adapt to parallel environments, load balancing is presented, and additionally, some voxelization techniques are developed to efficiently process the required geometric data. Numerous test cases are analyzed to demonstrate the efficiency and robustness of the proposed algorithm in various situations. The proposed algorithm consistently outperforms the conventional OGA, and also proves its robustness in the presence of high proximity objects, which highlights its suitability for large-scale multi-body problems.

Shear failure analysis of UHPC-NC composites interface with U-shaped studs

Given the extensive utilization of composite structures of ultra-high performance concrete (UHPC) and normal concrete (NC) in engineering applications, there has been a growing emphasis on studying the shear failure and mechanical properties analysis of the UHPC-NC interface. U-shaped studs assume a crucial role in reinforcing the UHPC-NC interface. A three-dimensional finite element model was constructed with different parameters to investigate the shear failure and mechanical properties of UHPC-NC incorporating U-shaped studs. The failure mode and the influences of diameter, internal span, stud number and concrete compressive strength on the shear characteristics of the UHPC-NC interface were analyzed. The numerical analysis indicates the final failure mode of the UHPC-NC interface with U-shaped stubs is the fracture of the U-shaped stud. The diameter and internal span of studs influence the interface shear capacity, while interface shear capacity is not sensitive to the compressive strength of UHPC and NC. Moreover, a calculation formula for the shear capacity of the UHPC-NC interface with U-shaped studs was proposed, considering the influence of stud diameter and internal span. An exponential function is recommended for predicting the interface shear slip and the stiffness corresponding to 0.55 times the shear capacity is adopted as the elastic shear stiffness. The interface shear slip model and the expression for elastic shear stiffness were established, providing a reference for approximate calculation without experimental data.

Anderson acceleration with approximate calculations: Applications to scientific computing

SummaryWe provide rigorous theoretical bounds for Anderson acceleration (AA) that allow for approximate calculations when applied to solve linear problems. We show that, when the approximate calculations satisfy the provided error bounds, the convergence of AA is maintained while the computational time could be reduced. We also provide computable heuristic quantities, guided by the theoretical error bounds, which can be used to automate the tuning of accuracy while performing approximate calculations. For linear problems, the use of heuristics to monitor the error introduced by approximate calculations, combined with the check on monotonicity of the residual, ensures the convergence of the numerical scheme within a prescribed residual tolerance. Motivated by the theoretical studies, we propose a reduced variant of AA, which consists in projecting the least‐squares used to compute the Anderson mixing onto a subspace of reduced dimension. The dimensionality of this subspace adapts dynamically at each iteration as prescribed by the computable heuristic quantities. We numerically show and assess the performance of AA with approximate calculations on: (i) linear deterministic fixed‐point iterations arising from the Richardson's scheme to solve linear systems with open‐source benchmark matrices with various preconditioners and (ii) non‐linear deterministic fixed‐point iterations arising from non‐linear time‐dependent Boltzmann equations.

Measurement of the reaction enthalpy of CO2 in aqueous solutions with thermographic and gravimetric methods

In this work, a new concept for the approximate determination of the reaction enthalpy of the reaction between CO2 and monoethanolamine (MEA) in aqueous solution was developed. For this purpose, a CO2 gas stream was flowed into aqueous MEA solutions with different concentrations of 1 wt%, 2.5 wt% and 7.5 wt%. The weight difference ∆T, which is based on the increase in CO2 bound by the MEA over time, was documented using a thermographic camera. The mass difference ∆m, which is also based on the increase in CO2 bound by the MEA over time, was determined using a balance. By determining ∆T and ∆m, an approximate calculation of the reaction enthalpy is possible. The deviation from the values from the data known from the literature was less than 5% in all experiments.

Computation of the Spatial Distribution of Charge-Carrier Density in Disordered Media.

The space- and temperature-dependent electron distribution n(r,T) determines optoelectronic properties of disordered semiconductors. It is a challenging task to get access to n(r,T) in random potentials, while avoiding the time-consuming numerical solution of the Schrödinger equation. We present several numerical techniques targeted to fulfill this task. For a degenerate system with Fermi statistics, a numerical approach based on a matrix inversion and one based on a system of linear equations are developed. For a non-degenerate system with Boltzmann statistics, a numerical technique based on a universal low-pass filter and one based on random wave functions are introduced. The high accuracy of the approximate calculations are checked by comparison with the exact quantum-mechanical solutions.

Origin of the intermediate-temperature magnetic specific heat capacity in the spin-liquid candidate Ca10Cr7O28

We present several approximate calculations of the specific heat capacity of the model for Ca10Cr7O28 proposed by Balz [], using methods including exact diagonalization, thermal pure quantum states, and high-temperature expansions. In none of these cases are we able to reproduce the magnitude of the zero-field specific heat capacity shown in the intermediate-temperature (∼5–15K) experimental data. We discuss possible reasons for the discrepancy, and what it might tell us about the magnetic Hamiltonian for Ca10Cr7O28. Published by the American Physical Society 2024

Loss minimization control of interior permanent magnet synchronous motor (IPMSM) based on approximate calculation

Loss minimization control of interior permanent magnet synchronous motor (IPMSM) based on approximate calculation

Lnvestigation of the Effect of a Mechanical Stress Concentrator on the Processes of Occurrence and Development of Cracks in Structural Elements of Aviation Equipment

The purpose of the research is investigation of the patterns of crack development in structural elements of aviation equipment from a stress concentrator under the influence of a force stretching along the main axis, symmetrical alternating loads (vibrations) and combined effects in order to determine the criticality of operation of aircraft products with crack-type defects, substantiation or refutation of the need for research and operation of the processes of development of stress-strain states preceding the occurrence of a crack, in systems and complexes of periodic, preflight and operational control of the technical condition of aircraft products.Methods. Еxperimental study of the patterns of crack development from a stress concentrator in structural elements of two form factors: a cylindrical sample (GOSТ 25347-82) simulating a stringer or a load-bearing structural beam, and a plate sample (GOSТ 1497-84), simulating an aircraft skin element. Cylindrical samples were subjected to deformation caused by the kinetics of rotation, plate samples were subjected to uniaxial tensile stress and the effects of alternating loads (vibrations) individually and in combination.Results. Тhe patterns of near-surface and deep crack development, their relationship with the frequency of application of symmetric alternating loads, have been studied. Еxpressions are established for the approximate engineering calculation of the material endurance limit, fracture surface area and constant endurance with an approximation accuracy Proceedings of the Southwest State University. Series: Control, Computer Engineering, of about 0.8. For samples in the form of flat plates, a stress-strain diagram is constructed, clearly illustrating the decrease in the endurance of the material to the effects of combined loads in relation to the effects of static tensile stresses only. Тhe approximate number of residual cycles before the structural element is destroyed is estimated, taking into account the amplitude-frequency parameters of the acting vibration in the presence of a crack in the sample. Тhe estimation method using the load intensity coefficient and mathematical expressions for its calculation is given.Conclusion. /t is concluded that it is necessary to analyze the dynamics of the development of stress-strain states (fatigue) of the material as states preceding the appearance of cracks in order to carry out sufficient control of the technical condition of structural elements of aircraft products.

Exact and approximate calculation and uncertain decision-making in children and adults: Evidence from fuzzy trace theory

The present study aimed to explore the role of exact and approximate calculation in predicting uncertain decision-making in children and emerging adults and the influence of intelligence on their uncertain decision-making was simultaneously considered. In the first study, forty emerging adults and fifty-four typically developing (TD) children completed the uncertain decision-making task—Iowa Gambling Task (IGT), exact calculation task, and approximate calculation task. In the second study, we further included data from forty-six intellectually gifted children with the same age as the TD children to investigate the relationship between calculation and uncertain decision-making performance. The results showed that emerging adults' and intellectually gifted children's IGT performance was superior to TD children. Exact and approximate calculation played different roles in predicting IGT performance in emerging adults and TD children: after controlling their intelligence scores, TD children's exact calculation negatively predicted their uncertain decision-making, whereas emerging adults' approximate calculation positively predicted their uncertain decision-making. Furthermore, intellectually gifted children's approximate calculation was positively associated with their uncertain decision-making, which is similar to emerging adults. This study verified and expanded fuzzy trace theory, and it shed light on developing and improving approximate calculation ability, which is beneficial to the increased ability of uncertain decision-making.

WORK STRESS AND ITS INFLUENCE ON THE EMPLOYEES OF A SERVICE COMPANY IN THE CITY OF MANIZALES

Objective: The study seeks to determine the levels of work stress in the employees of a service company, describing the causes and their financial impact.
 
 Theoretical Framework: The concepts of work stress defined as a general state of tension that triggers different emotional, cognitive, physiological and behavioral reactions are addressed, as well as some causing factors such as: Physical Environment, Job Demand, Knowing the tasks and interpersonal relationships.
 
 Method: The study has a mixed approach, where qualitative categories were given quantitative management of the data, to find numerical evidence and be able to explain in more detail the presence of the event. The ILO-WHO Work Stress scale was used as an instrument, which was applied to 33 employees of a Contact Center company in the city of Manizales.
 
 Results and Discussion: The results obtained revealed that work stress is below the limit of the intermediate stress range (81.09 / 90.02) and that due to Absenteeism and Turnover, the company has had costs of $43,995,586 COP according to approximate calculations.
 
 Research Implications: The evidence from the study showed information that allows companies in the service sector to generate strategies for stress management and contribute to reducing costs due to absenteeism and turnover, the above could be used in other sectors or companies in the region.
 
 Originality/Value: The value lies in contributing to the development of the state of the art on the subject and as a reference for future studies since the state of the art shows little research in Contact Center companies in Latin America, likewise for companies generating well-being strategies and the management of the stress.

OASIS: An interpretable, finite-sample valid alternative to Pearson’s X2 for scientific discovery

Contingency tables, data represented as counts matrices, are ubiquitous across quantitative research and data-science applications. Existing statistical tests are insufficient however, as none are simultaneously computationally efficient and statistically valid for a finite number of observations. In this work, motivated by a recent application in reference-free genomic inference [K. Chaung et al., Cell 186, 5440-5456 (2023)], we develop Optimized Adaptive Statistic for Inferring Structure (OASIS), a family of statistical tests for contingency tables. OASIS constructs a test statistic which is linear in the normalized data matrix, providing closed-form P-value bounds through classical concentration inequalities. In the process, OASIS provides a decomposition of the table, lending interpretability to its rejection of the null. We derive the asymptotic distribution of the OASIS test statistic, showing that these finite-sample bounds correctly characterize the test statistic's P-value up to a variance term. Experiments on genomic sequencing data highlight the power and interpretability of OASIS. Using OASIS, we develop a method that can detect SARS-CoV-2 and Mycobacterium tuberculosis strains de novo, which existing approaches cannot achieve. We demonstrate in simulations that OASIS is robust to overdispersion, a common feature in genomic data like single-cell RNA sequencing, where under accepted noise models OASIS provides good control of the false discovery rate, while Pearson's [Formula: see text] consistently rejects the null. Additionally, we show in simulations that OASIS is more powerful than Pearson's [Formula: see text] in certain regimes, including for some important two group alternatives, which we corroborate with approximate power calculations.

Метод приближенного вычисления интеграла Кирхгофа

The article proposes a method of approximate calculation of the wave field gradient by its distribution on the only one closed surface. This allows calculating the Kirchhoff's integral without additional calculations or measurements of the electromagnetic field and opens up the opportunity to use it in practice along with the field equivalence principle. The comparison of the Kirchhoff's integral calculation accuracy with its vector forms showed that the proposed approximation for the wave field derivative leads to additional methodological errors, which are equivalent to the stray signal at the level less then −40 dB. At the same time, the use of Kirchhoff's integral instead of a widespread field equivalence principle in the electromagnetic field transformation algorithms reduces their computing complexity to 20 times.

Testing of The Insulation Resistance and Turns Test Ratio (TTR) of The Distribution Transformers at PT PLN (Pesero) UP3 Sidoarjo

Electricity plays a vital role in human life and the economic growth of Indonesia. Therefore, a reliable electrical transmission and distribution system is essential. Transformers, especially in an industrial context, play a key role in power supply. Transformer maintenance is a critical step in maintaining a stable flow of electricity. This study adopts the Research and Development (R&D) method and focuses on measuring insulation resistance and voltage ratios in the context of transformer maintenance. The research was conducted at the Pole Transformer Substation (GTT) in P. Melati, Sidoarjo Regency, East Java, starting in August 2023. The research variables involve measuring the insulation resistance referring to IEC standards and measuring the voltage ratio to ensure proper transformer performance. The test results indicate that the insulation resistance in the transformer, both on the primary and secondary sides, meets the standards, demonstrating that the transformer functions well and safely. Voltage ratio measurements closely approximate theoretical calculations and fall within a tolerance of ± 0.5%. This study underscores the importance of transformer maintenance in maintaining a stable flow of electricity. Proper maintenance will prevent disruptions that can be detrimental, such as current leakage or short circuits. With good maintenance, the continuity of a reliable and safe electricity distribution service for consumers can be ensured.

Evolution of Transcript Abundance is Influenced by Indels in Protein Low Complexity Regions.

Protein Protein low complexity regions (LCRs) are compositionally biased amino acid sequences, many of which have significant evolutionary impacts on the proteins which contain them. They are mutationally unstable experiencing higher rates of indels and substitutions than higher complexity regions. LCRs also impact the expression of their proteins, likely through multiple effects along the path from gene transcription, through translation, and eventual protein degradation. It has been observed that proteins which contain LCRs are associated with elevated transcript abundance (TAb), despite having lower protein abundance. We have gathered and integrated human data to investigate the co-evolution of TAb and LCRs through ancestral reconstructions and model inference using an approximate Bayesian calculation based method. We observe that on short evolutionary timescales TAb evolution is significantly impacted by changes in LCR length, with insertions driving TAb down. But in contrast, the observed data is best explained by indel rates in LCRs which are unaffected by shifts in TAb. Our work demonstrates a coupling between LCR and TAb evolution, and the utility of incorporating multiple responses into evolutionary analyses.

Разработка способа расчета стоимости монтажа инженерных заграждений при изучении дисциплин инженерно-технической защиты

Specialists in technical information security deal with the physical security of various industrial objects. This article introduces a new method for approximating costs of installing a concertina razor wire obstacle. The method can be implemented as part of information security disciplines. The research involved a review of academic sources, scientific publications, and regulatory documents, which showed that courses of information security and engineering hardly ever cover the issue of costs calculation. The author developed a method for approximate calculation of the costs of installing reinforced barbed wire in its single-level concertina razor variant, including a simplified training sample for a hypothetical protected object. The results obtained can be applied as part of courses of engineering and information security, e.g., as laboratory tasks, tutorials, or research projects. The results may also be of interest to technical specialists involved in the engineering and technical data protection at various facilities that require physical security.

Enhancing levitation force of superconductors through wavelength optimization in Halbach permanent magnet arrays

Optimizing the wavelength (γ) of the Halbach array permanent magnet guideway (PMG) in superconducting maglev systems can improve levitation performance without consuming additional materials. The value of γ impacts the external field intensity He and gradient ∇He generated by the PMG. The total amount of magnetic field energy is fixed, and the γ essentially regulates the distribution of this energy. Reducing γ concentrates more magnetic field on the PMG surface, resulting in larger force and stiffness when the levitation height approaches zero. To validate this conclusion, experiments, approximate calculations and numerical simulations have been in all employed. However, excessive reducing γ at higher heights is not ideal as it tends to distribute most of the field energy below the desired height. The approximate method in this paper indicates that the levitation force is positively correlated with (He22Hp−He)∇He . Therefore, the objective is to determine the optimal γ that maximizes this index. Optimal values for γ at different heights have been identified, offering guidance for PMG design. Additionally, applying these findings to two existing PMGs results in 18% and 8.6% augmentation in levitation force respectively. Furthermore, a fully optimized PMG design has the potential to achieve a levitation force of nearly 10 kN m−1, while keeping the cross-sectional areas of the PMG and SC restricted to 4450 mm2 and 2500 mm2, respectively.

A Quick Calculation Method for Radiation Pattern of Submillimeter Telescope with Deformation and Displacement

Radiation pattern captures the electromagnetic performance of reflector antennas, which is significantly affected by the deformation of the primary reflector due to gravity and the displacement of the secondary reflector. During the design process of large reflector antennas, a substantial amount of time is often dedicated to iteratively adjusting structural parameters and validating electromagnetic performance. To improve the efficiency of the design process, we first propose an approximate calculation method of optical path difference (OPD) for the deformation of the primary reflector under gravity and the displacement of the secondary reflector. Then an OPD fitting function based on the modified Zernike polynomials is proposed to capture the phase difference of radiation over the aperture plane, based on which the radiation pattern will be obtained quickly by the aperture field integration method. Numerical experiments demonstrate the effectiveness of the proposed quick calculation method for analyzing the radiation pattern of a 10.4 m submillimeter telescope antenna at its highest operating frequency of 856 GHz. In comparison with the numerical simulation method based on GRASP (which is an antenna electromagnetic analysis tool combining physical optics (PO) and physical theory of diffraction (PTD)), the quick calculation method reduces the time for radiation pattern analysis from more than one hour to less than two minutes. Furthermore, the quick calculation method exhibits excellent accuracy for the figure of merit (FOM) of the radiation pattern. Therefore, the proposed quick calculation method can obtain the radiation pattern with high speed and accuracy. Compared to the time-consuming numerical simulation method (PO and PTD), it can be employed for quick analysis of the radiation pattern for the lateral displacement of the secondary reflector and the deformation of the primary reflector under gravity in the design process of a reflector antenna.

К оценке опасности выщелачивания некондиционного сырья в кучах

The issues of identification of environmental hazards when implementing the concept of the involvement of poor metal-containing raw materials and tailings from ore processing through the application of a new leaching technology with a detailed version of heap leaching on the earth have been considered. The methodology of identification of the environmental consequences of the implementation of the technology of deep processing of non-conventional mineral raw materials considering the impact of mineral waste on the environment of the field development region has been formulated. An environmental component of the complex ecological and economic effect comprised of the consistently implemented stages of the existence of the enterprise has been considered. The main factors of negative environmental impact received a quantitative assessment; the territories adjacent to the enterprise have been ranked by the degree of the anthropogenic impact. The options to determine the extent of damage caused by the contamination of ecosystems with heavy metals have been proposed. Models to determine the environmental damage caused by industrial effluents as the main transporting medium and the efficiency of utilization of substandard raw materials based on the profit criterion have been formulated. The mechanism of removal of reagents and solutions to the environment by airflows has been specified. An approximate calculation of parameters of the environmental contamination for ore leaching of ore raw materials in the Sadonskoye deposit has been provided. It has been demonstrated that the chemical contamination of soils is prioritized when determining the environmental hazard and the hazard for the enterprise employees. It has been proved that the combined ecological and economic model of assessment of the efficiency of utilization of substandard raw materials joins ecological and economic aspects within a single natural and anthropogenic system, whereas the ecological and economic efficiency of production is a function of integrating methods of field development, including the application of a safety criterion for ecosystems of the environment. The study results can be used for the adjustment to the legislation on mining in the Russian Federation.