Determination Of Coefficients Research Articles

Determination of stress intensity coefficients using PC LIRA CAD

Today, the issue of involving fracture mechanics approaches to the calculation of structures with cracks is becoming more and more relevant. For the most part, the implementation of such approaches is carried out using software complexes in which the finite element method is implemented. Among them, such software complexes as Abaqus, Ansys, Nastran stand out, where the implementation of fracture mechanics approaches is constantly being improved. However, the cost of licenses for the use of such complexes, especially in the conditions of Ukraine, does not allow most researchers to fully use such programs. Therefore, it is relevant to study the possibility of applying fracture mechanics approaches in software complexes, the use of which is free. In construction, a significant number of structures are isotropic bodies. Operation of most of them is accompanied by elastic deformations. If there are cracks in them, the load-bearing capacity is assessed using stress intensity factors (SIF). This article examines the possibility of determining the TIN based on the results of the specified stress-strain state obtained with the help of the free software package "PC LIRA-SAPR 2016 R5 (non-commercial)". The calculation of SIF is performed by a direct method based on the determined distribution of displacements and stresses around the crack tip. The crack is modeled by setting appropriate boundary conditions. Implementation of the direct method is performed in 2 ways. According to the 1st method, the SIF calculation is performed in the apical area according to the values of stresses and displacements. According to the 2nd method, the SIF is calculated by moving the node closest to the top of the crack. Approbation of the approaches was carried out on the test problem of tension of a plate with a central crack. A study of the influence of the dimensionality of the discrete model and the types of finite elements both outside the apex region and in the apex region itself was conducted. The obtained results showed the possibility of obtaining reliable SIF values in this software complex in two ways, subject to compliance with certain rules for building a discrete model.

Laboratory determination of hydrogen/methane dispersion in rock cores for underground hydrogen storage

Underground hydrogen storage in saline aquifers is a promising way to store large amounts of energy. Utilization of gas cushion enhances the deliverability of the storage and increases the volume of recovery gas. The key factor for the cushion characterization is cushion gas and storage gas mixing which can be used for simulation of mixing zone evolution. In this work coreflooding setup utilizing Raman spectroscopy is built and used for dispersion coefficient determination. Berea sandstone rock core is used as a test sample for setup validation and core entry/exit effects estimation. Dispersion for hydrogen and methane as displacing fluids is determined for 4 locations perspective for hydrogen storage in Poland is found. Reservoir structures most suitable for pure hydrogen or hydrogen/methane blend storage are selected.

A matrix-form complex variable method for multiple non-circular tunnels in layered media

This paper presents a matrix-form complex variable method that can predict the stress and displacement field around multiple tunnels in layered media. The proposed matrix-form method avoids complicated coefficient determinations and iterative algorithm, which effectively improves the computation efficiency. Firstly, the expressions for the stress and displacement field are given under the generalized complex variable theory. The conformal mapping technique and fast Fourier transform algorithm are used to formulate the matrix-form expressions of boundary conditions. Considering the boundary conditions of the tunnels and soil interfaces, the global matrix solution for multiple tunnels in layered media are obtained by assembling the matrix solutions of all single layers. The present theory is verified by comparison with the existing literature, finite element analysis and field data in engineering practices, and several numerical examples are given to reveal the effects of elastic properties, tunnels' position, equivalent layer and the layer thickness surrounding tunnels.

Design of Optimal Control Systems in the Frequency Domain by the Functional of the Generalized Work

The paper considers the problem of analytical design of optimal controllers (ADOC) for one-dimensional linear stationary objects according to the functional of generalized work (FGW) A. A. Krasovsky. The use of FGW in comparison with the quadratic performance functional greatly simplifies the calculation of the optimal controller — the calculation of its matrix of coefficients mainly consists in solving the linear matrix Lyapunov equation, which, in contrast to the nonlinear matrix Riccati equation, fundamentally reduces the amount of calculations. In addition, the use of FGW provides the best stability margins of the designed system in terms of amplitude and phase. This work is devoted to the development of a method for solving the ADOC problem A. A. Krasovsky in the frequency (complex) domain, which reduces the determination of the transfer function coefficients of the optimal controller for an object of order n to the solution of the corresponding system of n linear algebraic equations. In this regard, the proposed method for solving the ADOC problem by A. A. Krasovsky differs by a much smaller amount of calculations in comparison with the standard method, in which the Lyapunov equation is solved with the desired matrix of dimensions n * n. The proposed method for the synthesis of optimal control systems, which has an analytical nature, became the basis for solving the inverse problem ADOC A. A. Krasovsky, which consists in determining the values of the weight coefficients of the FGW, which provide the given primary quality indicators of the synthesized control system. Using its relations, a relatively simple method for calculating the FGW coefficients based on the given values of the error coefficients for the designed dynamic system has been developed.

Diffusion coefficients during regenerated cellulose fibers formation using ionic liquids as solvents: Experimental investigation and molecular dynamics simulation

Regenerated cellulose fibers (RCFs) are an essential type of bio-based chemical fibers. The preparation of RCFs using ionic liquids (ILs) as solvents is an efficient utilization of ecological resources. Investigating the diffusion coefficients during RCFs formation using ILs as solvents is vital due to the potential impact of the interaction between ILs and coagulants on the morphology and properties of RCFs. The determination of diffusion coefficients during RCFs formation is challenging due to its instantaneous and simultaneous nature. For this research, the method and apparatus for measuring the diffusion coefficients during RCFs formation were established, and the diffusion coefficients of various IL and coagulant systems were also explored under different formation conditions. In addition, the relationship between the diffusion coefficient, the formation condition and the self-diffusion coefficient of ILs were investigated using numerical simulation and molecular dynamics simulation. The results demonstrated that the formation conditions, particularly the temperature and composition of coagulants, significantly impact the diffusion coefficient. Lowering the temperature of the coagulants and incorporating ethanol with lower polarity reduced the diffusion coefficient. The diffusion coefficient of 1-ethyl-3-methylimidazolium diethylphosphate ([Emim]DEP) in the ethanol coagulation bath was 0.79 × 10−9 m2·s−1 at 293 K, which was nearly twice as small as that in the water coagulation bath. These findings were validated by molecular dynamics simulations. Modifying the formation conditions can regulate the structure and properties of the RCFs by affecting the diffusion coefficients during RCFs formation.

Distribution of resources beyond 5G networks with heterogeneous parallel processing and graph optimization algorithms

In this paper, a design model for resource allocation is formulated beyond 5G networks for effective data allocations in each network nodes. In all networks, data is transmitted only after allocating all resources, and an unrestrained approach is established because the examination of resources is not carried out in the usual manner. However, if data transmission needs to occur, some essential resources can be added to the network. Moreover, these resources can be shared using a parallel optimization approach, as outlined in the projected model. Further the designed model is tested and verified with four case studies by using resource allocator toolbox with parallax where the resources for power and end users are limited within the ranges of 1.4% and 6%. Furthermore, in the other two case studies, which involve coefficient determination and blockage factors, the outcomes of the proposed approach fall within the marginal error constraint of approximately 31% and 87%, respectively.

Equations and methodologies of inlet drainage system discharge coefficients: A review

Abstract Accurate determination of grate inlet discharge coefficients is crucial in reducing modeling uncertainties and mitigating urban flooding hazards. This review critically examines the methods, equations, and recommendations for determining the weir/orifice discharge coefficients, based on the inlet parameters and flow conditions. Reviewing previous studies for inlets showed that the discharge coefficient of rectangular inlets under subcritical flow ranges from 0.53 to 0.6 for weirs and from 0.4 to 0.46 for orifices, while in grated circular inlets, it falls between 0.115 and 0.372 for weirs and between 0.349 and 2.038 for orifices. For circular non-grated inlets under subcritical flow, the weir and orifice coefficients are in the range of 0.493–0.587 and 0.159–0.174, respectively. However, the orifice discharge coefficients of grated and non-grated inlets with unknown Froude number range between 0.14–0.39 and 0.677–0.82, respectively. For supercritical flow, the weir and orifice discharge coefficients of grated and non-grated rectangular inlets are 0.03–0.47 and 1.67–2.68, respectively. Previous studies showed that it is recommended to correlate the discharge coefficients with the approaching flow and Froude number under subcritical and supercritical flows, respectively. Yet, additional studies are recommended for a better understanding of the limits and parameters governing the flow transitional stage between weir and orifice and between subcritical and supercritical conditions. Moreover, further research is required to determine the weir and orifice discharge coefficients of circular inlets under supercritical flow as well as the orifice discharge coefficient range of rectangular non-grated inlets under subcritical flow. Finally, it is recommended to increase the road surface roughness to reduce Froude number, and thereby, increase discharge coefficients of street inlets. The aim of this review is to help inlet designers and authorities promote sustainable cities with resilient urban drainage systems and reduce the environmental, economic, health, and social impacts of urban drainage failure.

Comparative analysis of tracer studies in the determination of longitudinal dispersion coefficient.

The research presented in this paper is to determine the best tracer studies that will give acceptable estimates of longitudinal dispersion coefficient for Orashi river using rhodamine WT dye and sodium chloride as water tracer. Estimated results obtained for longitudinal dispersion coefficient for the case of rhodamine WT experiment ranges between 71 and 104.4 m2s-1 while that of sodium chloride experiment ranges between 20.1 and 34.71 m2s-1. These results revealed lower dispersion coefficient using sodium chloride as water tracer (WT) indicating that for larger rivers, sodium chloride should not be used as water tracer. The usage of sodium chloride as water tracer in the estimation of longitudinal dispersion coefficient is recommended in smaller streams as NaCl is relatively conservative. The established equations for both cases of investigation are proving satisfactory upon validation as degree of accuracy of 100.0% was obtained using discrepancy ratio (Dr). Standard error (SE), normal mean error (NME) and mean multiplication error (MME) of the developed equations is better when compared with other existing equations. However, Equation (17) is satisfactorily recommended.

A High-Resolution Method for the Experimental Determination of the Heat Transfer Coefficients of Industrial Nozzle Systems in Heat Treatment Plants

In industrial plants, metal strips are quenched using convective heat transfer. This involves accelerating gas through a nozzle system onto the material to be quenched, resulting in a fast and uniform cooling process. The efficiency of the heat transfer is determined by the specific nozzle system. The presented work is focussed on the analysis of the heat transfer by forced convection through impingement jets both theoretically and experimentally. A unique method for determining the forced convective heat transfer coefficient is described and its application to industrial size nozzle arrays of annealing-line cooling sections is presented.

Determination and Analysis of Radiation Shielding Properties of Some Selected Building Materials

<i>Background: </i>Radiation shielding primarily is based on the principle of attenuation of beams of X-ray or gamma radiation by absorption or scattering of the radiation that results due to the interaction between penetrating radiation and matter, radiation shielding properties such as attenuation coefficients obtained as a result of interaction between X-rays and gamma rays with target materials helps to study and confirm the appropriate building materials used for radiation shielding purposes. The linear attenuation coefficient required by radiation engineers in the design and analysis of radiation facilities has been determined and analysed for both gamma ray source Cs-137 and X-ray sources for 662 keV and 60- 120 kVp respectively. <i>Methods: </i>The determination of linear attenuation coefficient was evaluated by the formulation of building materials such as lead, granite, aluminium and concrete by calculating and comparing both experimental and theoretical results for 662 keV and 60-120 kVp using collimated Source-Material-Detector geometry method and XCOM software respectively. <i>Conclusion: </i>The results agreed with similar experimental works and the use of XCOM software with a percentage deviation of 0.44% - 11% at the 95 % confidence level. It was concluded that the results will go in a long way in assisting engineers and radiation professionals in the design and protection of radiation facilities.

Loading Determination of DMTr-substituted Resins for Large-scale Oligonucleotide Synthesis.

The loading (i.e., substitution) of solid supports for oligonucleotide synthesis is an important parameter in large-scale manufacturing of oligonucleotides. Several key process parameters are dependent on the substitution of the solid support, including the number of phosphoramidite nucleoside equivalents used in the coupling step. For dimethoxytrityl (DMTr)-loaded solid supports, the substitution of the resin is determined by quantitatively cleaving the DMTr protecting group from the resin under acidic conditions and then analyzing the DMTr cation extinction by UV/vis spectroscopy. The spectrometric measurement can be performed at 409 nm or the global extinction maximum of 510 nm. The substitution is then calculated based on the Lambert-Beer law analogously to the substitution determination of Fmoc-substituted resins. Below, the determination of the molar extinction coefficient at 510 nm in a solution of 10% dichloroacetic acid in toluene and subsequent determination of the DMTr loading of DMTr-substituted resins is reported. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Determination of the molar extinction coefficient at 510 nm in DCA Deblock solution Basic Protocol 2: Substitution determination of DMTr-substituted resins by cleavage of the DMTr cation.

Research on Path Tracking of Unmanned Spray Based on Dual Control Strategy

The high clearance spray is a type of large and efficient agricultural machinery used for plant protection, and path tracking control is the key to ensure the efficient and safe operation of spray. Sliding mode control and other methods are commonly used abroad to track vehicles, while fuzzy control, neural networks and other methods are commonly used at home. However, domestic and foreign research on autonomous agricultural machinery is mainly focused on tractors and other machinery, while research on self-propelled spray in high clearance is less abundant. This paper takes the path tracking algorithm in the integrated navigation system of spray as the main research goal, studies the path tracking control algorithm for straight lines and turning curves that can realize the automatic driving of spray by establishing the path tracking algorithm for unmanned spray based on dual control strategies, designs the path tracking controller, including the preview model theoretical path tracking controller and variable domain fuzzy controller, and determines the preview model through the design of the preview model theoretical path tracking controller. The lateral and longitudinal errors of the model algorithm are analyzed, and the driving characteristics under the complex spray road surface are analyzed. The design of the variable domain fuzzy predictor theory path tracking controller is proposed, and the design of the road model selection controller is calculated and analyzed in detail, including the determination of the road roughness coefficient and the selection of the range of the difference between the average value of the excitation before and after sampling, which improves the performance of the spray path tracking algorithm. The experiment shows that the proposed path tracking control algorithm can meet the path tracking requirements of unmanned spray in the current road environment, and provide a reliable solution for the automatic control of high clearance spray.

Kinetic stability of Chapman–Enskog plasmas

In this paper, we investigate the kinetic stability of classical, collisional plasma – that is, plasma in which the mean-free-path $\lambda$ of constituent particles is short compared with the length scale $L$ over which fields and bulk motions in the plasma vary macroscopically, and the collision time is short compared with the evolution time. Fluid equations are typically used to describe such plasmas, since their distribution functions are close to being Maxwellian. The small deviations from the Maxwellian distribution are calculated via the Chapman–Enskog (CE) expansion in $\lambda /L \ll 1$ , and determine macroscopic momentum and heat fluxes in the plasma. Such a calculation is only valid if the underlying CE distribution function is stable at collisionless length scales and/or time scales. We find that at sufficiently high plasma $\beta$ , the CE distribution function can be subject to numerous microinstabilities across a wide range of scales. For a particular form of the CE distribution function arising in strongly magnetised plasma (viz. plasma in which the Larmor periods of particles are much smaller than collision times), we provide a detailed analytic characterisation of all significant microinstabilities, including peak growth rates and their associated wavenumbers. Of specific note is the discovery of several new microinstabilities, including one at sub-electron-Larmor scales (the ‘whisper instability’) whose growth rate in certain parameter regimes is large compared with other instabilities. Our approach enables us to construct the kinetic stability maps of classical, two-species collisional plasma in terms of $\lambda$ , the electron inertial scale $d_e$ and the plasma $\beta$ . This work is of general consequence in emphasising the fact that high- $\beta$ collisional plasmas can be kinetically unstable; for strongly magnetised CE plasmas, the condition for instability is $\beta \gtrsim L/\lambda$ . In this situation, the determination of transport coefficients via the standard CE approach is not valid.

Penggunaan Media YouTube Ustadz Hanan Attaki dalam Aktivitas Dakwah

With the advancements in today's era, it is possible to create da'wah activities through social media, one of which is YouTube media. YouTube media is used by preachers to convey their preaching with the values conveyed in a simple and interesting way. The reason a preacher uses YouTube media for preaching activities is because YouTube media makes it easier and expands the preaching network that has been conveyed by the preachers. And the results in this research discuss the use of Ustadz Hanan Attaki's YouTube media in da'wah activities. It is true that the author knows that Ustadz Hanan Attaki uses all social media such as Instagram, Tiktok and YouTube. However, Ustadz Hanan Attaki in conveying his da'wah was more active in using YouTube media. One of the reasons why Ustadz Hanan Attaki made this YouTube media is because according to him, with this media it is easier to achieve the intended target and be accepted by someone, one of which is teenagers. And Ustadz Hanan Attaki in his preaching really maximizes YouTube media, his preaching content is designed and packaged as well and as attractively as possible so that it is in great demand among the public. The aim of this research is to find out how YouTube media is used in da'wah activities carried out by Ustadz Hanan Attaki. This research uses a quantitative approach, the data analysis carried out by the researcher is descriptive analysis, which uses regression tests, multiple linear tests, correlation coefficient tests and determination. Because the results of this research show a very high level on Ustadz Hanan Attaki's YouTube channel which currently has 2.58 million followers, 203 thousand views, and has 276 videos on it, this can have a positive influence on Hanan Attaki's YouTube channel. The YouTube media he uses to convey his preaching, which means that the more preaching material he conveys, the higher the level of positivity for listeners and viewers.

Spatial Dynamics of Rice Plant Health in Kerinci District Using Remote Sensing Data

One many districts sustain enhancement production rice in Jambi Province is Regency Kerinci. However if seen from amount production paddy, in the Regency Kerinci experience decline, based on data from Regency BPS Kerinci seen that amount production rice is unstable. Therefore it needs to be done monitoring to plant rice. Monitoring plant paddy can done through image remote sensing. Objective from this research, namely detect and analyze level health plant paddy quickly by using NDVI and NDRE parameter indices as well showing connection between health plant rice in quantity production rice in the Regency Kerinci . From the NDVI calculation it states that in 2018 the plants rice is in very good condition with an area of 11409.8 ha, in 2019 plants rice in condition well with an area of 10028.59, in 2020 plants rice in condition well with an area of 8382.77 ha , while in 2021 plants rice in condition both with an area of 9536.74 ha. Based on results NDRE calculation in 2018 crops paddy declared unhealthy or plant immature rice with an area of 8212.22, in 2019 plants unhealthy rice with an area of 7430.7 ha, in 2020 plants paddy declared healthy with an area of 6746.78 while in 2021 plants paddy declared unhealthy with an area of 13,392 ha. Multiple linear regression results showing coefficient determination of 0.814, that is that NDVI variable and NDRE variable simultaneous influential to variable amount production paddy amounting to 81.4%.

Determination of the extinction coefficients of CR-39, MR-8, and MR-10 organic glasses in the near-ultraviolet to visible region

The extinction coefficients of three commercial organic glasses referenced CR-39, MR-8 and MR-10 were determined from reflectance and transmittance spectra in the near-UV to visible region, using two different approaches. The first approach consists in the optimization of the extinction coefficient to fit the calculated transmittance to the optical measurements with a UV–Visible spectrometer. The second approach uses a simplified analytical expression of the extinction coefficient as a function of transmittance proposed in an article by S. Nemoto. The two calculation methods are compared and discussed. A table of complex refractive indices (including the determined extinction coefficients) is provided in the appendix, for open use.

Determination of Timewise-Source Coefficient in Time-Fractional Reaction-Diffusion Equation from First Order Heat Moment

This article aims to determine the time-dependent heat coefficient together with the temperature solution for a type of semi-linear time-fractional inverse source problem by applying a method based on the finite difference scheme and Tikhonov regularization. An unconditionally stable implicit finite difference scheme is used as a direct (forward) solver. While by the MATLAB routine lsqnonlin from the optimization toolbox, the inverse problem is reformulated as nonlinear least square minimization and solved efficiently. Since the problem is generally incorrect or ill-posed that means any error inclusion in the input data will produce a large error in the output data. Therefore, the Tikhonov regularization technique is applied to obtain stable and accurate results. Finally, to demonstrate the accuracy and effectiveness of our scheme, two benchmark test problems have been considered, and its good working with different noise levels.

Quantifying regional low flows under data scarce conditions

Estimating low flow quantiles is essential for regulating minimum flow requirements and ensuring water availability, ecological health, and overall system sustainability. This study aims to quantify regional low flows by analyzing low-flow time series in data-limited environments. We utilized annual minimum 7-day instantaneous streamflow data collected from gaging stations. Discordancy measure assessments revealed that all sites were homogeneous, forming a single region. We employed Easy-Fit Statistical Software to select the best-fit probability distribution model and determine estimation parameter values. Through goodness-of-fit tests (GOFs), the Generalized Pareto model emerged as the most suitable, predicting low flow quantiles for 100-year returns. Rigorous application of GOFs ensures the statistical soundness of the model, capturing underlying data patterns. A correlation coefficient determination (R2) of 0.989 demonstrates the high satisfaction of the selected distribution model. The developed regression line for the region exhibited strong agreement between predicted low flows and catchment area. Thus, accurate estimation proves valuable in environmental and human-influenced decision-making processes, providing insights into low-flow behavior and mitigating drought effects on aquatic ecosystems.

Determination of phase boundaries and diffusion coefficients of copper in spinel CuCr2Se4 and delafossite CuCrSe2 by galvanostatic intermittent titration technique (GITT)

Determination of phase boundaries and diffusion coefficients of copper in spinel CuCr2Se4 and delafossite CuCrSe2 by galvanostatic intermittent titration technique (GITT)

Physico-Mechanical Properties of Pumpkin Seeds in the Context of Drying Processes

The paper highlights the significance of the drying process in post-harvest cucurbit seed treatment technology. To improve the effectiveness of drying high-moisture seeds, a plant construction design was introduced, incorporating the concept of providing varied heat distribution to a vigorously agitated seed layer. The paper validates the necessity of refining the dimensional, frictional, and aerodynamic properties of pumpkin seeds to determine the optimal operating modes for the proposed dryer. (Research purpose) To identify the physical and mechanical properties of pumpkin seeds by defining their dimensional, frictional and aerodynamic characteristics. (Materials and methods) The study employs one-factor experimental research methods with subsequent statistical data processing. An experimental study was conducted on the physical and mechanical properties of Volzhskaya Grey pumpkin seeds possessing a standard moisture content ranging between 9.3 and 9.7 percent. Well-known laboratory apparatuses, namely the «conical tank» and the «inclined plane», were used to determine the natural repose angle and to enhance the accuracy of friction coefficients determination. For analyzing the aerodynamic properties of the seeds, the K-293 Petkus air separator was employed. (Results and discussion) Research methods were developed and experimental plants were described. It was established that with a probability confidence level of 0.95, the static friction coefficients of pumpkin seeds on a solid steel sheet, a perforated steel sieve and on rubber are 0.473, 0.418, 0.481, respectively, and the dynamic friction coefficients under the identical conditions are measured as 0.331, 0.293, 0.337. The average angle of natural repose is found to be 22 degrees, the midsection area is 97.94 square millimeters, the soaring velocity is 7.083 meters per second, the windage coefficient stands at 0.196 and the aerodynamic drag coefficient is 0.136. (Conclusions). The assumption that enhancing the drying efficiency of vegetable seeds can be achieved by implementing a diverse thermal energy supply to continuously moving mass inside the apparatus is confirmed, provided that the seeds do not stick together in layers resulting in blockage of the coolant flow. An improved design of the dryer configurations has been developed and, to validate its optimum design and technological specifications, an in-depth analysis of the seeds' dimensional, frictional, and aerodynamic attributes has been conducted.