Practical Calculation Method Research Articles

Perspectives of Experts in the Selection of Contents for a Course of Differential Equations in Engineering

This study investigates the teaching of Differential Equations in engineering education, focusing on expert opinions from diverse institutional backgrounds. The primary objectives were to understand expert perspectives on essential course content, justify their content choices, measure institutional gaps, and highlight the range of professional profiles. Through qualitative interviews with nine experts from academia and industry, we explored their views on the integration of Differential Equations in engineering curricula. The findings reveal a consensus on the importance of basic concepts to support physical models. Notably, experts highlighted variational calculus and energy representations as critical yet underrepresented areas in Differential Equations courses, essential for modeling complex, nonlinear problems. The study also states on the growing importance of computational methods and software in engineering education, advocating for an integrated approach aligning theoretical concepts with real-world applications. The expert opinions revealed a significant institutional influence on content perception, demonstrating a gap between traditional theoretical focus and modern, application-oriented approaches. The study suggests a need for curricular innovation in differential equations education, emphasizing practical applications and computational methods to bridge this gap between the two institutions considered in which the experts are adhered to.

Experimental and numerical study on honeycomb T-beam bridge deck

The inefficiency in the construction of intermediate diaphragms for T-beam bridges (referred to as conventional T-beam), has long been a significant research concern. This study focuses on a novel bridge deck design (referred to as honeycomb T-beam), which effectively eliminates the need for intermediate diaphragms, thus enhancing construction efficiency. Segment models of both conventional T-beam and honeycomb T-beam were designed and fabricated, and their transverse mechanical performance was compared through transverse static tests. Additionally, numerical simulations using ABAQUS were conducted and validated with experimental data. Based on the numerical model of honeycomb T-beam, crack width calculation and reinforcement optimization were performed. The main conclusions are as follows: (1) The design of honeycomb T-beam allows for less reinforcement, making it more economical while ensuring that the bearing capacity reaches the same level. (2) Honeycomb T-beam exhibits superior durability and bearing capacity, with a failure mode that is more ductile. (3) The results of numerical simulation highly coincide with experimental results. Besides, this paper proposes and validates a practical method for crack width calculation. (4) Parametric analysis show that increasing the reinforcement area at right inner hole of honeycomb T-beam by 10% can enhance the bearing capacity by 18%. Based on this, design suggestions are made for honeycomb T-beams and other perforated structures.

Experiments and calculation methods on the tensile capacity of a single blind bolt anchored in a circular CFST section

Composite tubular joints that connect the steel brace and circular concrete-filled steel tubular (CFST) chords are crucial for the performance of entire composite truss structures. While welding is traditionally used for these connections, bolted connections offer an alternative in challenging environments where on-site welding is not feasible. The emergence of blind bolts provides an innovative solution for bolted CFST joints by offering bolted fastening without needing access to the inner surface of a closed section. This paper focuses on the tensile performance of a single blind bolt anchored in a circular CFST section. Experiments are conducted on three different configurations of blind bolts: non-anchored blind bolt with washer, anchored blind bolt without washer, and anchored blind bolt with washer. Based on the tests, the failure mode, the ultimate capacity, and the stiffness of the CFST-blind bolt specimens are investigated. The research findings show that the stiffness and ultimate capacity of the specimen are highly influenced by the bolt diameter, concrete strength, and effective embedment length, as well as the configuration of the blind bolt. And the effective embedment length has the most significant effect on the bearing capacity of the specimen. For every 30 mm increase in bolt effective embedment length, the bearing capacity of the specimen increases by at least 25 %. Finally, practical calculation methods are proposed to determine the ultimate capacity of CFST-blind bolt joints with various configurations under tensile action. The proposed calculation methods demonstrate high accuracy, as evidenced by the good agreement between the calculated values and experimental results.

Analytical model for evaluating bond strength of steel rebar in cracked concrete considering confinement effect

This study delves into the intricate relationship between concrete cracking and bond strength, a critical factor in transferring forces between concrete and steel rebars. While previous research has often overlooked the impact of concrete cracking on bond strength and overestimated the beneficial effects of external confinement, this study aims to fill these gaps. A new failure criterion is introduced to predict bond strength of steel rebar in cracked concrete, considering the influence of concrete crack roughness and steel rebar surface features on force transfer at their interface. This criterion incorporates an interlock capacity coefficient that considers crack kinematics and the mentioned factors, enhancing the evaluation of effective compressive strength of cracked concrete in the limit analysis. Leveraging the Mohr-Coulomb failure criterion, an adaptable failure criterion accounts for crack kinematics, concrete damage, and confinement level to assess force transfer at the concrete/steel rebar interface. The developed criterion offers a practical calculation method to estimate bond strength in cracked reinforced concrete (RC) members with various confinement setups. Validation of this criterion and approach involved comparison against experimental results from 127 specimens, confirming its effectiveness and reliability in predicting bond strength in real-world scenarios.

Heavy-atom tunnelling in singlet oxygen deactivation predicted by instanton theory with branch-point singularities

The reactive singlet state of oxygen (O2) can decay to the triplet ground state nonradiatively in the presence of a solvent. There is a controversy about whether tunnelling is involved in this nonadiabatic spin-crossover process. Semiclassical instanton theory provides a reliable and practical computational method for elucidating the reaction mechanism and can account for nuclear quantum effects such as zero-point energy and multidimensional tunnelling. However, the previously developed instanton theory is not directly applicable to this system because of a branch-point singularity which appears in the flux correlation function. Here we derive a new instanton theory for cases dominated by the singularity, leading to a new picture of tunnelling in nonadiabatic processes. Together with multireference electronic-structure theory, this provides a rigorous framework based on first principles that we apply to calculate the decay rate of singlet oxygen in water. The results indicate a new reaction mechanism that is 27 orders of magnitude faster at room temperature than the classical process through the minimum-energy crossing point. We find significant heavy-atom tunnelling contributions as well as a large temperature-dependent H2O/D2O kinetic isotope effect of approximately 20, in excellent agreement with experiment.

Application of ternary nanofluid and rotating cylinders in the cooling system of photovoltaic/thermoelectric generator coupled module and computational cost reduction

Innovative cooling systems and solar panel modeling approaches have become critical for effective photovoltaic module performance and higher energy efficiency. In the present study, a novel cooling system for thermoelectric generator integrated photovoltaic module is proposed. Three dimensional coupled photovoltaic module/thermoelectric generator/cooling channel system is numerically analyzed by using Galerkin weighted residual finite element method. The cooling channels include rotating circular cylinders, with ternary nanofluid serving as the cooling medium. Three dimensional coupled numerical simulations are carried out for various values of cylinder’s rotational speed (rotational Reynolds number, Rew between 0 and 5000), number of channels with rotating cylinders (N between 2 and 8), size of the cylinders in the cooling channel (RC between 0.006H and 0.433H) and nanoparticle amount in water (ϕ between 0 and 3%). Higher rotational speed of the cylinders, higher nanoparticle loading and higher channel number with cylinder contribute positively to the performance enhancement of the photovoltaic-thermoelectric generator coupled system. In the case of motionless cylinder in cooling channels, larger cylinder sizes have negative impact on the performance. By using cylinders that rotate at the fastest possible rate together with the usage of ternary nanofluid and only water, photovoltaic-cell temperature drops of 61.6 °C and 61 °C in comparison to un-cooled photovoltaic are achieved. When compared to motionless cylinder arrangements, cell temperature reductions of 4.3 °C and 3 °C are achieved by using the fastest rotation speeds for the base fluid and nanofluid. The temperature of the photovoltaic cells decreases and the thermoelectric power increases as the number of rotating cylinders in the cooling channels increases while temperature of the cell drops by 2 °C from N=2 to N=8 and becomes 4.3 °C as compared to motionless cylinder configuration. An efficient computational method by using proper orthogonal decomposition is proposed. While the computational time is reduced by a factor of 1/50, the approach is effective in properly predicting the variation in photovoltaic-cell temperature. The proposed cooling system and practical computational method are useful for further development and optimization of efficient thermal management of photovoltaic panels and integrated systems.

BODY SURFACE AREA AND USAGE AREAS

Body surface area is an anthropometric parameter used in many areas like drug dose adjustment, burn treatment, and determination of fluid requirement, as well as to calculate the basal metabolic rate. It is critical for many medical specialties, such as chemotherapy, transplantology, burn therapy, and toxicology. Until the 19th century, researchers looked for easy ways to calculate body surface area and developed various formulas. There were several different formulas derived from height and weight measurements to predict body surface area. Historically, the DuBois & DuBois formula is the most used, but Mosteller's formula is more popular due to its simplicity. The accuracy of the body surface area formulas, which are still in use today, is still being debated because they are determined by a few sample studies, and different sizes such as children and adults are not taken into consideration in sample selection. New and practical calculation methods are tried to be determined. This review aims to investigate the emergence of the body surface area and where it is used.

Comprehensive Fatigue Analysis and Practical Design Methodology for Weld Toes in the Sphere of Welded Hollow Spherical Joints in Grid Structures

This paper addresses the issue of fatigue in grid structures, a topic of interest in engineering and academia. The goal is to establish a practical fatigue design calculation method for weld toes in welded hollow spherical joints (WHSJs). The study focuses on commonly used steel tube-WHSJs in grid structures, conducting 25 constant amplitude and four variable amplitude fatigue tests on tube–sphere joints (TSJs) to derive corresponding S-N curves. Using ANSYS, the hot spot stress concentration coefficient Kh at the weld toes in 22 TSJs was calculated, resulting in a numerical solution for Kh ranging from 2.0550 to 4.8600. Based on this, fatigue design methods were established using nominal stress amplitude and hot spot stress amplitude as fundamental parameters. Within a fatigue design reference period of two million cycles, the allowable nominal stress amplitude for TSJs is 22 N/mm2, and the allowable hot spot stress amplitude is 66 N/mm2. The study also conducted macroscopic and microscopic analyses on fatigue fractures of TSJs, revealing that the weld toe in the sphere of TSJs is the primary site for fatigue crack initiation. This research provides practical calculation methods for fatigue design in WHSJ grid structures, contributing to their broader application.

Field measurement of ground effect for road traffic noises

In ASJ RTN-Model 2018, which was proposed by the Acoustical Society of Japan, a practical calculation method of the ground effect in A-weighted overall level for road traffic noise is specified by relatively simple formulae. The method is derived from the solution of the ground effect based on wave theory. By the practical calculation method, the attenuation level by the ground effect for a relatively long distance between the source and receivers tends to become larger on softer ground. Especially in the cases of lower sound source positions as specified in the ASJ RTN-Model 2018, the excess attenuation becomes large. To investigate the appropriate treatment of the ground condition in the case of road traffic noise propagation on soft ground, the authors have performed a field measurement of road traffic noise. The measurement results were compared with calculation results by both the ASJ RTN-Model 2018 and the theoretical solution based on the wave theory. From the comparison, the features of the propagation characteristics obtained by the ASJ RTN-Model 2018 were discussed.

Practical calculation methods for ground noise correction factors in airport noise prediction model

This paper describes the results of a study to improve the calculation method for predicting aircraft noise around Japanese airports using our prediction model. The model limited the calculation frequency for the insertion loss caused by noise barriers and buildings to a single 250 Hz, which does not reflect the actual frequency spectrum of aircraft. Therefore, to simulate more realistic conditions, we calculated a synthetic attenuation chart from the frequency spectra of several representative aircraft models and included the chart in our model. We then compared the calculated values with the measured values to verify the validity and discussed the influence of this change on the airport noise contours. In addition, for noise propagation of engines and auxiliary power units on the ground, an improved calculation formula for ground surface attenuation, taking into account the ground condition, has already been reported. In this paper, we report on the implementation of this calculation formula in our model and discussion of the calculation results.

Numerical analysis method of equivalent deformation parameters for grouted arch dam abutment fractured rock masses considering scale effects and anisotropy

Research on the equivalent deformation parameters of grouted arch dam abutment rock masses has recently emerged as a key in the design, construction and stability assessment of arch dams. With the aim of synthetically considering scale effects and anisotropy of the rock mass equivalent deformation parameters after grouting, in this paper, a practical numerical calculation method is developed. First, the Latin hypercube sampling method is introduced to generate a network of fractures of the arch dam abutment rock mass. Subsequently, the finite element models of the rock masses with different sizes in various directions are constructed. On this basis, equivalent continuum theory and cohesive element model are applied for numerical calculation of grouting fractured rock masses. Then, the scale effect and anisotropy of the deformation modulus of rock mass under different grouting conditions are investigated. Finally, the Jinping super-high arch dam is taken as an example to validate the theoretical significance and application effect of the proposed method. The analysis results indicate that the process of fracture and fragmentation of grouted rock masses is characterized precisely, and the deformation of material units can be described as fully as possible to calculate more realistic equivalent deformation parameters of the fractured rock masses.

Research on a Non-Synchronous Coordinated Reduction Method for Slopes Based on the Hoek–Brown Criterion and Acoustic Testing Technology

In the process of the evolution of rocky slope instability, the decay deterioration rate of cohesion c and internal friction angle φ are different, and there are also differences in the order and degree of their impact on slope stability; thus, it is of great theoretical value to propose a more practical calculation method for the reduction in slope degradation. This paper combines the Hoek–Brown criterion and an acoustic test method to estimate the mechanical parameters of slope rock mass; the correlative relationship within the double-strength parameter reduction was established by introducing advanced reduction steps (ARS), n, and correlation factor, λ, and a non-synchronous coordinated reduction (NSCR) method for the double parameters of slopes was proposed. Furthermore, methods for determining the comprehensive safety factor (CSF) of slopes during the coordinated reduction of double parameters are comparatively analyzed. The results of the application of engineering examples show that the strength of the slope rock mass is significantly reduced after several blast disturbances, and the equivalent cohesion is reduced from 1.05 MPa to 0.89 MPa, while the internal friction angle is reduced from 25.68° to 21.77°. The CSF calculated using the W. Yuan-2 method is closer to the results of the limit equilibrium method and is suitable for the calculation of the CSF of the NSCR of slopes. The slope CSFs show a trend of first increasing and then decreasing with the increase in n; FS = 3.349 when n = 50, with a relative error of only 8.1% compared to the results calculated using the limit equilibrium method. The NSCR method remediates the blindness of the traditional strength reduction method in double-parameter reduction and ensures that the reduction range of the internal friction angle is no lower than its residual strength limit value, making it practical and feasible for slope stability analysis.

Numerical Analysis of Temperature Deformation Characteristics for Super-High Arch Dams considering Solar Radiation Effects

Considering that the effect of solar radiation on the super-high arch dam temperature field remains poorly studied, the calculation accuracy of dam temperature deformation is unable to be guaranteed accordingly. To address the issue, the solar radiation effect is adequately taken into consideration by proposing a practical calculation method based on the ray-tracing algorithm, the precomputation algorithm, and the ASHRAE clear sky model in this paper. With the aid of the ASHRAE clear sky model, the solar radiation received by the super-high arch dam and reservoir water is calculated. The shading effects are calculated by means of the ray-tracing algorithm, and the precomputation technology is introduced to further enhance the computational efficiency. Finally, to guarantee the authenticity of the calculation results, the dam thermodynamic parameters are inversed by employing the hybrid genetic algorithm. Based on the application in a real-life case, we concluded that around one third of the entire dam radial temperature deformation was attributable to solar radiation during continuous sunny days. The analysis results signify a critical role for taking account of the solar radiation in dam deformation calculation. Furthermore, the practicability and utilization prospect of the proposed method was verified.

Flexural behavior and crack width prediction of UHPC slabs reinforced with FRP bars

This paper aims to investigate the effects of FRP-bar configurations on the flexural behavior of the FRP-reinforced ultra-high-performance concrete (UHPC) deck slab and to propose the calculation method of crack width. Firstly, flexural tests were performed on six FRP-reinforced UHPC slab specimens with varying bar diameters, reinforcement ratios, cover thickness, and slab thicknesses. The load-deflection responses, load-FRP strain relations, and cracking behavior are measured and discussed. The results show that under service loads, the maximum crack widths of all specimens are around 0.03 mm–0.04 mm, which is significantly less than the permitted 0.5 mm in international codes for FRP-reinforced structures. At similar reinforcement ratios, a small FRP-bar diameter with a corresponding reduced bar spacing increases the ultimate capacity and energy dissipation ability. The effects of FRP-bar configurations are minor under service loads, while beyond these loads decreasing the bar diameter is beneficial for reducing the bar strain and crack width. Subsequently, by developing a practical calculation method of the stress of FRP bar embedded in UHPC slab and calibrating the bond coefficient between FRP bar and UHPC against test data, an engineer-friendly calculation method of crack width is proposed. Comparisons between predicted and experimental results indicate the proposed method is capable of producing accurate and safe predictions. The results may give guidance to designers on the appropriate FRP-bar configurations and the control of crack width for the FRP-reinforced UHPC deck slab.

Complex peptide macrocycle optimization: combining NMR restraints with conformational analysis to guide structure-based and ligand-based design

Systematic optimization of large macrocyclic peptide ligands is a serious challenge. Here, we describe an approach for lead-optimization using the PD-1/PD-L1 system as a retrospective example of moving from initial lead compound to clinical candidate. We show how conformational restraints can be derived by exploiting NMR data to identify low-energy solution ensembles of a lead compound. Such restraints can be used to focus conformational search for analogs in order to accurately predict bound ligand poses through molecular docking and thereby estimate ligand strain and protein-ligand intermolecular binding energy. We also describe an analogous ligand-based approach that employs molecular similarity optimization to predict bound poses. Both approaches are shown to be effective for prioritizing lead-compound analogs. Surprisingly, relatively small ligand modifications, which may have minimal effects on predicted bound pose or intermolecular interactions, often lead to large changes in estimated strain that have dominating effects on overall binding energy estimates. Effective macrocyclic conformational search is crucial, whether in the context of NMR-based restraints, X-ray ligand refinement, partial torsional restraint for docking/ligand-similarity calculations or agnostic search for nominal global minima. Lead optimization for peptidic macrocycles can be made more productive using a multi-disciplinary approach that combines biophysical data with practical and efficient computational methods.

The practical calculation method of the high-order moment spectra of quadratic Gaussian stochastic processes

In the frequency-domain analysis of structures under non-Gaussian excitations, the determination of high-order moment spectra of excitations remains a substantial challenge due to the complexity and inaccuracy of the existing estimation method. This paper proposes the practical calculation method of the high-order moment spectra models for quadratic Gaussian stochastic processes. Firstly, the expressions of the first four moment spectra of quadratic Gaussian stochastic processes are derived based on the relation between the high-order cumulant function of Gaussian stochastic processes and high-order moment function. Secondly, a practical calculation method of the high-order moment spectra is presented by the ratio of the corresponding component moment functions. Finally, two numerical examples are investigated to validate the efficiency and accuracy of the practical calculation method of the high-order moment spectra for quadratic Gaussian stochastic processes.

Force Calculation of Mechanical Model of Pile-anchored Support Structure Based on Elastic Foundation Beam Method

With the widespread use of deep foundation pit engineering in engineering construction, the force calculation problem about deep foundation pit support engineering has become a common problem in today’s engineering construction process. In this paper, based on the elastic foundation beam method, a simplified mechanical model of pile-anchored structure is proposed, and a systematic and practical calculation method is proposed for the force and deformation calculation of deep foundation pit support structure. The method simplifies the support structure as a vertically placed elastic foundation beam, the support, anchor and geotechnical body are replaced by a spring system, the spring stiffness of geotechnical soil can be calculated by the deformation modulus of geotechnical soil, and a systematic calculation method is proposed for the dynamic characteristics of the construction and structure of the foundation pit project; Based on the monitoring data of a deep foundation pit project, the calculation method of the simplified mechanical model proposed in this paper is verified, and the theoretical calculation value is compared with the field monitoring results; Single factor analysis is carried out on the detailed parameters of pile-anchor supporting structure to study the influence of cable prestress, cable dip Angle, pile diameter, pile length and other related parameters on the deformation and stress characteristics of supporting structure. Then the orthogonal combination of all factors is carried out to propose the optimization design. The results show that the maximum settlement deformation of the calculated value is 23.437 mm, and the maximum settlement deformation of the monitored value is 26.517 mm, and the difference between them is small. The maximum bending moment is 1210 kN⋅m after 150 kN and 250 kN horizontal prestressing is added to the second- and third-layer anchors respectively. After optimization, the maximum bending moment of pile row is 336.87 kN⋅m, and the maximum horizontal displacement of pile body is 16.505 mm, which is reduced by 11.97% compared with the original design.

What is an exposure-response curve?

Exposure-response curves are among the most widely used tools of quantitative health risk assessment. However, we propose that exactly what they mean is usually left ambiguous, making it impossible to answer such fundamental questions as whether and by how much reducing exposure by a stated amount would change average population risks and distributions of individual risks. Recent concepts and computational methods from causal artificial intelligence (CAI) and machine learning (ML) can be applied to clarify what an exposure-response curve means; what other variables are held fixed (and at what levels) in estimating it; and how much inter-individual variability there is around population average exposure-response curves. These advances in conceptual clarity and practical computational methods not only enable epidemiologists and risk analysis practitioners to better quantify population and individual exposure-response curves but also challenge them to specify exactly what exposure-response relationships they seek to quantify and communicate to risk managers and how to use the resulting information to improve risk management decisions.

Gray level residual field: an effective metric for pixelwise matching quality evaluation in local digital image correlation

Gray level residual (GLR), also known as correlation residual field or image difference, reflects the intensity differences between reference and deformed images. In finite element-based global digital image correlation (DIC), GLR field can be readily computed and has been successfully used for crack or damage detection. The computation of pixelwise GLR field requires dense displacement results, which can be obtained using mesh interpolation in global DIC. To obtain the GLR field in subset-based local DIC, in which results are obtained at discrete calculation points, a simple, efficient and practical computation method for GLR field is presented, which accounts for the influence of illumination variations unavoidably occurred in real DIC tests. The proposed method can be easily implemented on both central process unit and graphics process unit to realize real-time visualization. Experiments showed that the GLR field can quantitatively and intuitively evaluate the pixelwise matching quality and provide clearer and finer locations for new components or textures (e.g. cracks) presented in deformed images. By fully leveraging the pixelwise matching quality information provided by the GLR field, the capability and robustness of local DIC is expected to be further enhanced.

A fast and practical computation method for magnetic resonance simulators.

This work aims to develop a fast and practical computation method for MR simulations. The computational cost of MR simulations is often high because magnetizations of many isochromats are updated using a small step size on the order of microseconds. There are two types of subsequences to be processed for the simulations: subsequences with and without RF pulses. While straightforward implementations spend most of their time calculating subsequences with RF pulses, there is a method which efficiently reuses the computation for repetitive RF pulses. A new method for efficiently processing subsequences with RF pulses is proposed. Rather than using an iterative update approach, the proposed method computes the combined transition which combines all transitions applied iteratively for each subsequence with RF pulses. The combined transition is used again when the same subsequence is used later. The combined transitions are cached and managed using a least recently used algorithm. The proposed method was found to accelerate the simulation by ˜20 times when 3.9 million isochromats were simulated using spin-echo sequences. Even on a laptop computer, the proposed method was able to simulate these sequences in ˜3.5min. An efficient method for simulating pulse sequences is proposed. The proposed method computes and manages combined transitions, making MR simulation practical on a wide range of computers, including laptops.