General Method For Calculation Research Articles

Role of three-dimensional vortex motions on horizontal eddies in an open-channel cavity

AbstractLateral cavities are a popular object of study in hydraulic research as they are widely found in rivers and hydraulic facilities and significantly impact flow patterns, sediment transport, and water quality in aquatic ecosystems. While the effects of open-channel cavities on various aspects including characteristics of three-dimensional structures have been extensively studied, the role of vertical flow structures in the cavity has not been focused on. This study examines the relationship between the shallowness parameter and the three-dimensional flow effects on the dynamics of an open-channel lateral cavity flow with horizontal vortex motion, comparing the conventional two-dimensional model (2DC), advanced depth-integrated models including general bottom velocity calculation method (GBVC) with the ability to consider vertical flow structures, simplified bottom velocity calculation method with the shallow water assumption (SBVC), a three-dimensional model (3DC), and experimental data. The comparison results demonstrate that the three-dimensional flow effect significantly impacts the velocity distribution and vortex evolution in the cavity. The GBVC model demonstrates a good agreement with the flow patterns by the 3DC model and experimental results in the cavity, whereas the 2DC and SBVC models are unsuitable for deep-water conditions.

Merge Loss Calculation Method for Highly Imbalanced Data Multiclass Classification.

In real classification scenarios, the number distribution of modeling samples is usually out of proportion. Most of the existing classification methods still face challenges in comprehensive model performance for imbalanced data. In this article, a novel theoretical framework is proposed that establishes a proportion coefficient independent of the number distribution of modeling samples and a general merge loss calculation method independent of class distribution. The loss calculation method of the imbalanced problem focuses on both the global and batch sample levels. Specifically, the loss function calculation introduces the true-positive rate (TPR) and the false-positive rate (FPR) to ensure the independence and balance of loss calculation for each class. Based on this, global and local loss weight coefficients are generated from the entire dataset and batch dataset for the multiclass classification problem, and a merge weight loss function is calculated after unifying the weight coefficient scale. Furthermore, the designed loss function is applied to different neural network models and datasets. The method shows better performance on imbalanced datasets than state-of-the-art methods.

Nitrogen fertilization produces divergent effects on canopy structure between indica and japonica rice reflected in leaf to panicle ratio based on deep learning

High throughput plant phenomics enables precise quantification of structural information for the complex crop canopy. Leaf to panicle ratio (LPR) in terms of light interception is a physiological trait we formerly developed to clarify the light distribution pattern within the canopy of japonica rice. Here, using the methodology of deep learning neural network (Transformer Feature Pyramid Network), we proposed a general method for LPR calculation for both japonica and indica rice, and tested it in the study on variation of canopy structure across nitrogen (N) fertilization modes. Field experiments over three years (2020–2022) with three nitrogen levels and two basal to topdressing ratios were conducted for two cultivars of each japonica and indica rice. Results showed contrasting dynamic variation of LPR between the two species, ascending for indica rice but descending for japonica rice along with the grain-filling progression. Indica rice had larger temporal variation in LPR than the japonica. N topdressing significantly increased the LPR of indica rice cultivars at same N level, whereas that of japonica was dependent on N level and genotype. Morphological measurement revealed that the differential response of LPR to N was associated with the height difference between the flag leaf and panicle, panicle curvature, leaf area index and panicle area index. Correlation analysis revealed that the relation between LPR and grain yield was significantly positive for indica rice but negative for japonica rice. Our findings suggest that LPR can effectively reflect the characteristics of canopy structure as affected by cultivars and fertilization modes, thus being a valuable physiological indicator for crop science.

A hybrid framework for manufacturing feature recognition from CAD models of 3-axis milling parts

With the rapid development of computing technologies, the CAX software are widely used in mechanical engineering. The part model is designed in computer-aided design (CAD) software, the planning process is planned in computer-aided process planning (CAPP) software, and the machining process is simulated in computer-aided manufacturing (CAM) software. However, there are still digital gaps between design, process, and manufacturing, which affect the integration and efficiency of engineering information. Manufacturing features are considered digital carriers that can bridge the gap. The knowledge of design, process, and manufacturing can be integrated on manufacturing features to achieve the information flow across different engineering applications. However, the existing approaches cannot solve the feature recognition problem very well. The recognition criterion of these approaches do not have the generalization ability. And they also do not deal with the interacting features appropriately. To improve the performance of feature recognition of 3-axis milling parts, this paper proposed a hybrid feature recognition framework based on graph approach and rule approach. The hybrid framework solves the recognition problem of interacting features with the layered decomposition method. And the general wire criterion is proposed to improve the robustness. In addition, the general calculation method of adjacency attributes is also the original contribution. The final experimental results show that the proposed hybrid framework works well and can be applied to the actual engineering applications.

Engineering Method for Calculating the Limiting Amplitudes of Stress Cycles for Structural Steels

In large-sized metal structures, various stress concentrators are often present, which affects the operation of the material. These are intermittent bonds, holes, welded joints, material defects, etc. As a result of overloads under the action of an external cyclic load on structures in the area of stress raisers, the cycle asymmetry, the level of maximum stresses and deformations increase. In this case, the determination of the limit values of the stress cycles can be performed using a diagram of the limit stress amplitudes. The paper presents an engineering method for calculating the limiting stress amplitudes and constructing Hay’s diagrams. It is based on the use of mathematical models of classical linear and structural-mechanical fracture mechanics. Analytically and by calculation, the validity of the method is shown, which consists in determining the endurance limits and limiting stress amplitudes under high-cycle loading in a wide range of variation of the cycle asymmetry coefficient for ferrite-pearlite steels with a yield strength of up to 400 MPa. Thus, a generalized calculation method has been developed for determining the endurance limits for high values of cycle asymmetry and cycle stresses. The error of the method is estimated in the area of low-cycle load. The influence of constant and average load in a cycle on the endurance limit has been investigated both for high-cycle and low-cycle loading. The proposed approach allows to construct Smith and Hay’s fatigue diagrams for the tensile region, taking into account the structural characteristics of the material and the error allowed for engineering calculations.

Dynamic characteristic modeling of left ventricular assist devices based on hysteresis effects

ObjectiveThe purpose of this study is to develop a new model for the dynamic characteristics of left ventricular assist devices (LVADs) interacting with the cardiovascular system under constant-speed modes. MethodsA new hysteresis model is established on the basis of the hysteresis effect and turbomachinery principles. The simulation results from the hysteresis model were compared with the inertia model. The in-vitro experiment results of a centrifugal pump (from literature) and the unsteady computational fluid dynamics (CFD) simulation results of an axial pump were used as the benchmarks. ResultsCompared with the inertia model, at the partial support mode, the relative estimation error of the time to the maximum and minimum pump flow (Q) in the hysteresis model decreased at least 16.3% cardiac cycle (Tc) in the centrifugal pump and at least 1.9% Tc in the axial pump, indicating its ability to simulate more realistic Q fluctuations. Moreover, the hysteresis model could predict an accurate time distribution of different Q. ConclusionThe hysteresis model provides a general calculation method for simulating the dynamic characteristics of constant-speed LVADs under interaction with the cardiovascular system. It is more accurate than the inertia model. SignificanceThe hysteresis model is helpful for the rapid estimation of unsteady dynamic characteristics in absence of a physical pump prototype at the preliminary design stage.

Current Status and Enhancement Strategies for All-Solid-State Lithium Batteries

ConspectusAll-solid-state lithium batteries have received considerable attention in recent years with the ever-growing demand for efficient and safe energy storage technologies. However, key issues remain unsolved and hinder full-scale commercialization of all-solid-state lithium batteries. Previously, most discussion only focused on how to achieve high energy density from the theoretical perspective. Herein, we analyze the real cases of different kinds of all-solid-state lithium batteries with high energy density to understand the current status, including all-solid-state lithium-ion batteries, all-solid-state lithium metal batteries, and all-solid-state lithium–sulfur batteries. First, we propose a general calculation method to visually compare the above battery systems partly due to no normative parameters for solid-state batteries. After then, we discuss and interpret the key parameters and current situation of all-solid-state lithium batteries. Through the summary and analysis of the frontier, one can find that, although some breakthrough has been made in energy density and areal capacity for solid-state batteries, there are still many aspects to be improved such as power density and rate performance. Therefore, in response to the challenges, we propose possible directions for future development, including the ways to prepare different kinds of solid electrolyte films to reduce the proportion of inactive substances in the cell. The advantages and disadvantages are discussed about three typical solid-state electrolyte films (inorganic solid electrolyte, solid polymer electrolyte, and composite solid electrolyte). In addition, potential candidate anodes with high capacity and cathodes with high voltage and/or high capacity are also discussed in details. The combination of lithium metal anodes with ultrahigh capacity and cathodes with both high capacity and high voltage is the current mainstream direction. However, the interface problems have become the most pressing factor on the application. Therefore, we introduce the origin of interfaces and interphases and discuss how to build a stable electrode/solid electrolyte interface. One thing is clear that artificial solid electrolyte interphases and composite solid electrolytes are effective to obtain stable anode/solid electrolyte interfaces, which can prevent lithium from constantly reacting with solid electrolytes, ensure the uniform lithium deposition and prevent the formation of lithium dendrites. For the cathode/solid electrolyte interface, reasonable composite cathodes, multilayer design, and composite solid electrolytes can optimize the electrode and interface for stable cycles at high voltages and high current densities. Furthermore, the contribution of high-throughput computations and machine learning is introduced in accelerating materials screening and development. Among them, progress has been made in solid electrolytes and artificial solid electrolyte interphases through materials genome engineering and machine learning. Finally, we provide some outlook for the future development. We hope that this Account could help understand the current status and inspire more future breakthrough for all-solid-state lithium batteries.

Test Method and Application of High-Temperature Operating Life of Automobile Chips

The high temperature operating life (HTOL) test is an important item in the reliability test of automobile chips. The goal of the HTOL test is to evaluate the durability of automobile chip products under high-temperature loads. Based on the common-used standards, calculation models, and related research experience of evaluating the reliability of electron devices at home and abroad, this paper focuses on the model of the high-temperature durability test model of automobile chips and analyzes different factors affecting the high-temperature operating life test. The general calculation and analysis model and method of the high-temperature operating life test of automobile chips are presented in this paper, which provides a reference for determining the indicators of the high-temperature operating life test of automobile chips.

Generalized calculation method for steel profiles embedded in concrete – embedment depths, design at the ultimate limit state and design aids

Generalized calculation method for steel profiles embedded in concrete – embedment depths, design at the ultimate limit state and design aids

CALCULATION OF ANNULAR PLATES ON AN ELASTIC BASE WITH A VARIABLE BEDDING FACTOR

The application of the analytical method ‒ the method of direct integration ‒ to calculations of building structures in the form of circular plates and plates on a continuous variable elastic base is considered. It is noted that there are no proposals for a general analytical method for calculation of annular plates on a variable elastic base in the literature. And the need for such a method is obvious, since it makes it possible to estimate the accuracy of finite element analysis. A detailed description of the algorithm of the direct integration method is not given in the paper, and all the calculation formulas for the circular plate are taken from the authors’ already published article. The results of numerical implementation of this algorithm for specific examples are considered. In order to verify the results of calculations by the author’s method, computer modeling of the considered circular plates in PC LIRA-SAPR and their calculations by the finite element method have been performed. The reaction of the foundation is described by the Winkler model with a variable bedding factor. The calculation of a concrete slab that is rigidly pinched on the inner contour and articulated on the outer contour is performed. And calculation of a steel plate with rigid pinching on the outer contour and articulated on the inner contour. In the first case, the bedding factor is assumed constant, and in the second case, it changes according to the linear law. The calculations showed that the discrepancy between deflections calculated by the finite-element method and the author’s method does not exceed 1%, and the results of radial and circumferential moments calculation differ more considerably, amounting to 10%. The authors explain this difference by the inaccuracy of the numerical analysis associated with a semi-automatic method of constructing a finite-element mesh, which should be made finer. The densification of the mesh in the manual mode of its partitioning significantly reduces the discrepancy between the results of calculating the deflections, radial and circumferential bending moments by the finite-element method and the author’s method.

A new equivalent stress approach based on complex invariants: The COIN LiWI method

In this paper, a new equivalent stress approach is presented, which builds on the basic ideas of linear wave interference (LiWI) and thus leads to physically valid signals. Complex invariants (COIN) were introduced for the derivation, whereby a generalized calculation method with consideration of the tension shear strength ratio could be derived following the formulation of Mertens (1988). The LiWI approach was also applied to an equivalent stress formulation from the German FKM guideline (Rennert et al., 2021). Both approaches were tested and compared with signed von-Mises using existing experiments with a wide range of different loads, e.g. nonproportional, variable, frequency superimposed.

General Power Flow Calculation for Multi-Terminal HVDC System Based on Sensitivity Analysis and Extended AC Grid

The power flow calculation of the multiterminal high voltage direct current (MTDC) system is essential for planning sustainable energy sources and power flow analysis for the MTDC system. However, the traditional unified methods require a large system of non-linear equations leading to low calculational efficiency. Also, for a large DC grid, there is a concern about the convergence of sequential methods. This paper proposes a general power flow calculation method for voltage source converter (VSC) based MTDC systems. Based on an extended topology of an AC grid, a generalized calculation model of the MTDC power flow is proposed. Then, a novel sensitivity analysis-based power flow (SAPF) method is proposed, in which the state variables of the extended AC grid are calculated via sensitivity analysis. With a smaller system of equations, the proposed SAPF method has less computational burden than the traditional unified methods and causes no convergence problem compared to sequential methods. To further improve the calculational efficiency, the sensitivity-based variable updating is adopted to accelerate the iterative process. By comparing with the existing methods in calculating power flow for different MTDC systems, including large systems with multiple AC/DC grids, the effectiveness and scalability of the proposed methods are verified.

Nodal conservation principle of potential energy flow analysis for energy flow calculation in energy internet

The energy internet analysis method based on energy flow analysis can be used to analyze complex flow phenomena of material and energy effectively. However, there is a lack of general conservation principles for energy flow modeling when analyzing the coupling of energy flow with different types of material and energy. Hence, it is necessary to explore the general transmission principles of energy flows based on the physical mechanism. The objective of this paper is to obtain the conservation principles of energy flow at the node and the state parameters characteristics, then develop an effective energy flow calculation method. Firstly, concepts of potential parameters are extended to the general physical potentials, such as voltage, pressure, temperature, and concentration. Then, the application limitations of Kirchhoff's loop law from circuit calculation to energy network analysis are analyzed. The nodal conservation principle of potential energy flow (PEF) and the nodal mixing principle of potential is proposed. Finally, a general PEF calculation method suitable for energy internet is proposed. The results of the 14-node heating solution network show that the general PEF calculation method can effectively analyze the heating solution network, and the number of iterations does not increase with the increase of PEF types.

Prediction of flow and sediment transport rates into closed-end channels for turbidity current intrusion

Turbidity current intrusion often occurs in canals, approach channels and tributary areas of large reservoirs, causing sedimentation problems in these environments. Many models and semi-empirical equations have been proposed to calculate flow and sediment transport rates for turbidity current intrusion, under an assumption that the current front can keep propagating freely in the channel before dying out, but the effect of the finite length of closed-end channels has rarely been considered. A self-similar solution to the vertical two-dimensional model for turbidity currents is used to obtain the equation of the maximum possible length for the intrusion of turbidity currents. The maximum possible length is then used to modify an existing discharge equation for turbidity current intrusion in long channels and establish a more general calculation method that can be applied for intrusion in closed end channels. Data from two existing flume experiments are used to calibrate the derived equation of sediment transport rate for turbidity current intrusion. Field measurements obtained from several tributary mouths in the Xiaolangdi Reservoir are also used to calibrate the derived intrusion discharge equation. The agreement between predictions and observations, as well as the comparison between the proposed calculation method and the one before modification, demonstrate that the intrusion discharge is not only determined by the depth of turbid water and sediment concentration at the inlet of the tributary channel, but also influenced by the ratio of the real intrusion length to the maximum possible intrusion length.

Engineering mathematical calculation method for curved surface die design of metal materials

The design of metal material curved surface die is a common problem in engineering. From the perspective of intelligent manufacturing, this paper analyzes the mechanism and design key points of metal material curved surface die, establishes the mathematical model of die design by using the matrix equation method, and puts forward a general engineering mathematical calculation method of segmented die design. Based on the look-up table calculation, this scheme can simplify the calculation method and reduce the calculation error, which is suitable for general engineering die processing calculation.

Analytical Calculation of Transient Short-Circuit Currents for MMC-Based MTDC Grids

DC short-circuit current calculation is necessary to design and protect modular multilevel converter-based (MMC-based) multiterminal dc (MTDC) grids. In this article, a general and analytical short-circuit current calculation method is proposed for bipolar MTDC grids. For pole-to-pole (P2P) faults, the superposed fault equivalent network of the MTDC grid is first developed in the frequency-domain. Then, a decoupling method based on the network inductance ratio is proposed, which simplifies the high-order network into the superposition of several independent two-order <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RLC</i> circuits. As a result, the short-circuit current can be expressed as the sum of the currents of these <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RLC</i> circuits. For pole-to-ground (P2G) faults, the phase-domain dc line impedance considering the coupling effects is determined based on its modal-domain parameters, so that the P2G fault current can be calculated using the method of the P2P fault. The proposed method’s effectiveness is verified through simulations and experiments, and the calculation error is classified and analyzed. Compared with the existing methods, the proposed method is more accessible, more accurate, and available for hand-solution.

Study on numerical calculation of flow structures in a curved open channel with advanced depth-integrated models

A better understanding of flow structures distribution in rivers is crucial to determine the safety degree of rivers. A practical and reliable model is required to overcome the issue of the long computational time of a three-dimensional calculation model and the lack of computation detail of a two-dimensional calculation model for flow structures distribution simulation in rivers. This paper presented an advanced depth-integrated numerical calculation method called the bottom velocity calculation (BVC) to reproduce the flow structures in a curved open channel. BVC method is an integrated multiscale simulation of flows in rivers that can evaluate vertical distributions of velocities and bottom velocity distributions by introducing depth-averaged horizontal vorticity and horizontal momentum equations on a water surface. It has several models, such as simplified bottom velocity calculation (SBVC) with shallow water assumption and general bottom velocity calculation (GBVC) method without the assumptions. The advantages of the BVC method, including SBVC and GBVC models, are validated in this paper using experimental datasets of a curved open channel and compared to two-dimensional and three-dimensional models. The results show that the BVC method has good reproducibility to simulate the flow structures distribution in the channel.

Energy Consumption Analysis of High-Speed Trains under Real Vehicle Test Conditions

The study collected statistics on the actual operation of national railway electric multiple units (EMUs) and compared the energy consumption of different EMU models at different speed levels. An important method for studying the relationship between speed and energy consumption of EMUs has been constructed based on group method of data handling to reflect how the energy consumption of different EMU models changes with speed. The energy consumption of CRH2 and CRH380A EMUs on flat and sloping lines was compared. Moreover, the start-up energy consumption of CRH2 and CRH380A EMUs was compared. The effect of the number of stops of CRH2 and CRH3 EMUs on energy consumption was analyzed. Furthermore, an idea for improving the general expression and calculation methods of traction energy consumption of EMUs was proposed. Finally, suggestions on the construction of a traction energy consumption information system were provided, and the selection of different high-speed EMU models and the reasonable determination of the operating speed were discussed.

Carrying Capacity Calculation Method Based on Operation Chain and its Application

Abstract Railway border reloading station is an important node of the interconnectivity of international railway transport corridor, which overall carrying capacity is critical to keep the corridor unblocked. Compared with general technical stations, the organization of cargo reloading at the station definitely has an impact on transport efficiency and capacity in addition to arriving, departing and conventional technical operations. By analyzing the operation steps and characteristics of railway border reloading station, the concept of overall carrying capacity was defined and its composition was confirmed. Based on this, the operation chain analysis method of the overall carrying capacity of the border reloading station was developed. Then we conduct a case study of Erlian station. Five operation chains were built to calculate the overall carrying capacity and identify the bottleneck. The operation chain analysis method proposed in this paper overcomes the defect of not considering the impact of the reloading operation on station capacity in the existing general technical station transport capacity calculation method. It can comprehensively consider the facilities and equipment of the station and the current traffic flow, so as to accurately find the weak links among them and provide a basis for the improvement of the transportation organization. Therefore, the conclusion is more scientific and reasonable.

A highly accurate metadynamics-based Dissociation Free Energy method to calculate protein\u2013protein and protein\u2013ligand binding potencies

Although seeking to develop a general and accurate binding free energy calculation method for protein–protein and protein–ligand interactions has been a continuous effort for decades, only limited successes have been obtained so far. Here, we report the development of a metadynamics-based procedure that calculates Dissociation Free Energy (DFE) and its application to 19 non-congeneric protein–protein complexes and hundreds of protein–ligand complexes covering eight targets. We achieved very high correlations in comparison to experimental binding free energies for these diverse sets of systems, demonstrating the generality and accuracy of the method. Since structures of most proteins are available owing to the recent success of prediction by artificial intelligence, a general free energy method such as DFE, combined with other methods, can make structure-based drug design a widely viable and reliable solution to develop both traditional small molecule drugs and biologic drugs as well as PROTACS.