Calculation Method Research Articles

Enhancing intersection safety in autonomous traffic: A grid-based approach with risk quantification

Existing studies on autonomous intersection management (AIM) primarily focus on traffic efficiency, often overlooking the overall intersection safety, where conflict separation is simplified and traffic conflicts are inadequately assessed. In this paper, we introduce a calculation method for the grid-based Post Encroachment Time (PET) and the total kinetic energy change before and after collisions. The improved grid-based PET metric provides a more accurate estimation of collision probability, and the total kinetic energy change serves as a precise measure of collision severity. Consequently, we establish the Grid-Based Conflict Index (GBCI) to systematically quantify collision risks between vehicles at an autonomous intersection. Then, we propose a traffic-safety-based AIM model aimed at minimizing the weighted sum of total delay and conflict risk at the intersection. This entails the optimization of entry time and trajectory for each vehicle within the intersection, achieving traffic control that prioritizes overall intersection safety. Our results demonstrate that GBCI effectively assesses conflict risks within the intersection, and the proposed AIM model significantly reduces conflict risks between vehicles and enhances traffic safety while ensuring intersection efficiency.

Причины повреждений корпусных конструкций в носовой оконечности судов

The operation of marine vessels, especially large-tonnage ones, is accompanied by the occurrence of serious damage to hull structures within bow in stormy conditions. A new mechanism to explain the catastrophic destruction of the side grillages of large-tonnage ships in the area of the bow is proposed. Simulation of the process of flow around the fore end when it is digged in a wave using SPH technology showed that when the flow speeds around the fore end occur when the vessel moves in developed waves, there is a sharp drop in pressure in certain areas of the bow end. This circumstance can lead to the occurrence of cavitation that is confirmed by modeling the process of flow around the fore end using ANSYS FLUENT software. During stall cavitation, a cavitation cavern of considerable size may arise, the collapse of which is accompanied by the occurrence of hydrodynamic loads that can destroy hull structures. A calculation method is proposed that allows one to estimate the magnitude of hydrodynamic loads acting on the ship’s hull during the collapse of a cavitation cavern. To prevent damage to the bow in storm conditions, a number of constructive measures have been proposed. One of the options for solving the problem is to install a deck fairing in the bow that eliminates the negative influence of structural cavitators in the traditional design when the bow is digged in the wave. It is also possible to install a compressed air supply system to those areas of the bow where vacuum occurs when a liquid flows around when digged in a wave.

Метод определения эффективности вариантов организации перевозок барже-буксирными составами

A study has been conducted on the method of evaluating options for organizing cargo transportation by barge-tow trains based on determining their effectiveness. Using the methods of the classical theory of transport processes, this problem has no quantitative solution, since it is not possible to take into account the regrouping of the composition during the passage of the route. To overcome this problem, additional mathematical tools have been developed for constructing integral time and velocity matrices, an objective function and graphs of the ratios of the total volume of transported cargo to the time it was en route. The consistent implementation of the proposed tools ensures the coherence of the calculation methods for determining the effectiveness of a flight with and without regrouping on the route, and also makes it possible to select the most appropriate option for organizing transportation. The cumulative result allows us to reflect the method of evaluation, comparison and selection of the most effective option for organizing a flight / group of flights, taking into account the ability to set individual parameters for the movement of the train and cargo. An example of approximation of the coordinate points of the route from the Nizhne-Svirsky shipping lock to Lake Ladoga is illustrated, as well as an example of discretization of an inland waterway section according to a three-level model. The parameters of equalization of the objective function of determining the efficiency of cargo transportation are considered. It is concluded that the optimal transportation option can be carried out on the basis of a combined approach, when several parameters are taken into account or sequentially set in the process of modeling the operation of ships. Graphs have been built that demonstrate the differences between the ways of organizing flights.

Comparative Analysis of Framed-Tube & Braced-Tube System in Tall Buildings Using ETABS

Abstract: Since the rigid frame became popular in the first half of the 20th century, tall buildings with structural systems have evolved. The development of underlying frameworks for tall structures lays on reasonable realism, economy of material utilization, effortlessness and polish, and worry for constructability. We are now able to build buildings that are ever higher thanks to cutting-edge building materials, sophisticated computational software, and sturdy structural systems. The rationale behind the creation of structural systems for tall buildings is to achieve architectural expression, ensure safety and serviceability, and make rational and effective use of materials. The use of composite structures, which combine the advantages of various materials, has been the trend in structural systems for tall buildings. In both static and dynamic conditions, these high-rise structures ought to be able to withstand a variety of lateral loads, such as wind load and earthquake load. This study examines the responses of the Framed Tube, Braced Tube, structural systems to various parameters such as Story displacement, Story drift, Story shear, and time period. The analysis focuses on 60-story structures situated in Seismic Zone III with medium soil conditions. The static analysis of the structures is conducted using the linear static method, which involves wind load calculations using the force coefficient method. On the other hand, the dynamic analysis is performed using the response spectrum method, with wind load calculations carried out using the gust factor calculation method.

Green Wheels, Greener Wallets: Economic Viability of Last-Mile Delivery Fleet Electrification in Case of Latvia

The analysis of internal combustion engine vehicle (ICEV) usage habits in the DPD Latvija company and the study of the specifics of its last-mile delivery transport business will allow to understand whether electromobility solutions can make the company more efficient. The question addressed in the research is whether the electrification of the delivery vehicle fleet can reduce transport expenses for the company and under what conditions. For estimation of direct and indirect costs of transport acquisition and usage Total Cost of Ownership (TCO) is used. The company’s daily operation parameters and technical data of the used vehicles VW e-Crafter and VW Crafter 35 Kasten/long base are considered in the study. Net Present Value (NPV) and Internal Rate of Return (IRR) calculation methods are used for analyzing the investment project. The expense of the creation of electrical vehicle charging infrastructure is not considered, because the company’s daily routine allows to cover all charging processes overnight by using domestic sockets together with Mode 2 chargers. All technical data and calculations were made for deliveries in a city cycle. In financial terms of owning delivery transport, the company is using a 5-year operational lease with 0% first payment. The obtained results in terms of TCO comparison showed a slight advantage by using EV after 5 years of last-mile delivery service per 1 vehicle – 706.98 Euro at 31200km a year or 100km in the working day of 6-day working week (156000km in 5-year is under 160000 warranty condition). The calculation is performed for DPD Latvija 213 ICE vans of a total 240-vehicle fleet. Results of NPV, NPVI, and IRR with a comparison rate of 10.6% for EV case clearly show a sufficiently good return. The Net Present Value of the solution is 89271.92 Euro and the Internal rate of return is 48.05%. The study proves that the electrification of the last-mile delivery company's fleet is economically justified and within 5 years. In the process of electrification, the company will reduce its expenses – by 1.45%, which increases the net annual profit by 0.13%. The main conclusion is that the company will not incur losses by switching to an environmentally friendly vehicle, the capital investment in a realistic scenario pays off already from the 3rd year. Nevertheless, the authors of the study recommend evaluating delivery vehicles with higher driving range parameters, because during peak delivery and seasons with cold weather, the company may experience unplanned downtime and expenses due to the need for additional charging time at public charging networks on the road, that could lead to financial losses and need for TCO calculation corrections.

Thermal Transport Properties of Two-Dimensional Janus MoXSiN2 (X = S, Se, and Te).

The design of Janus materials offers an effective means of regulating both their physical and chemical properties, leading to their application in various fields. However, the underlying mechanism governing the modulation of the thermal transport characteristics through the construction of Janus materials remains unclear. In this work, we introduce VI-group elements into the MoSi2N4 structure, yielding two-dimensional Janus MoXSiN2 (X = S, Se, and Te) and systematically investigate their thermal transport properties based on first-principles calculation methods. Our findings reveal that the lattice thermal conductivities (κl) of MoSSiN2, MoSeSiN2, and MoTeSiN2 are 47.2, 24.3, and 40.6 W/mK at 300 K, respectively, significantly lower than that of MoSi2N4 (224 W/mK). Such low κl values mainly come from the introduction of X atoms, which enhances phonon scattering and reduces phonon vibration frequencies. In addition, MoTeSiN2 exhibits a higher κl compared to MoSeSiN2, contrary to the trend observed in most materials containing VI-group elements, where κl decreases gradually from S to Te. This anomalous behavior can be attributed to the competitive result between its lower phonon vibrational frequency and weaker phonon anharmonicity of MoTeSiN2. This work elucidates the inherent mechanism governing the modulation of thermal transport properties in Janus materials, thereby enhancing the potential application of Janus MoXSiN2 in engineering thermal management.

Comparing Numerical and Analytical Methods for Heat Loss Determination of District Heating Systems

Energy efficiency assessment considers the heat losses in district heating systems. For instance, life cycle assessments of such engineering structures require knowledge of the heat losses during their use phase. Therefore, it is essential to have the most accurate knowledge of the heat losses of a district heating system. In this study, three different methods for the determination of specific heat losses for buried preinsulated steel pipes are compared. The first method involves an analytical calculation in accordance with EN 13941, while the second utilizes an equivalent circuit approach. The third method employs finite element analysis. The objective was to evaluate the accuracy of the methods, the achievable range of results, and the effort required to solve the respective calculation algorithms. Therefore, typical 2-dimensional cross sections including different pipe diameters were selected. In situ measurements were not part of this study. Consequently, the analysis centres on the deviation between the methods. All three methods determine the heat loss in both the supply and return pipes. While the analytical calculation method cannot determine temperatures in the soil, the equivalent circuit method can handle more complex tasks and gives detailed results at predefined points in the model. With the finite element method, a high degree of detail can be achieved, but the requirements for solving the algorithms increase. An emerging trend in district heating involves reducing operational temperatures in both new and existing networks. This will change the relation between heat losses and heat delivered to the customers. Subsequently, an increasing interest in the actual heat losses and the precision of calculation is expected within this development. Therefore, it remains essential to evaluate the performance of different models

Coupling coefficient calculation method of circular coil with bilateral finite magnetic shields at horizontal misalignment in wireless power transfer systems

AbstractThe coupling coefficient determines the transfer efficiency of the wireless power transfer (WPT) system. The magnetic leakage can be reduced, and the coupling coefficient of the coil can be enhanced by adding a magnetic shield. Thus, the transfer efficiency of the WPT system can be improved. However, when the receiving coil is added with magnetic shield and occurs horizontally misaligned, the coupling coefficients between the coils with the magnetic shield can only be calculated by finite element simulation, and there is no calculation method for the coupling coefficient of two circular coils with bilateral finite magnetic shield at horizontal misalignment. Therefore, based on Maxwell's equations and Bessel's function, the formula of the coupling coefficient between circular coils at coaxial is derived by the subdomain hierarchical analysis (SHA) method. On this basis, the coupling coefficient calculation formula between circular coils at horizontal misalignment is further derived by using the boundary vector equivalence (BVE) method. The results show that the maximum experimental error is not more than 5.58%, and the longest average time of the algorithm is not more than 1.282 s, which verifies the effectiveness and rapidity of the proposed method.

Superconducting electronic device response linearity calculation method using discrete fourier analysis

A highly effective method of the device linearity calculation on the stage of the device development is worked out and reported. The method allows expressing the linearity in terms of the achievable spurious-free dynamic range (SFDR) of the created devices, in particular superconductive electronic devices, and therefore can be easy correlated with the obtained experimental data. The algorithm scheme and the method accuracy are considered and discussed in detail.

Multiple-Bird-Strike Probability Model and Dynamic Response of Engine Fan Blades

Bird strikes pose one of the most significant threats to aviation safety, often leading to substantial loss of life and economic damage. Many bird strike incidents involve multiple birds. However, in previous bird strike studies, the problem of multiple bird strikes has often been neglected. In this paper, the bird slicing process of a rotating engine fan is examined, and a probability model is introduced to assess the risk of multiple impacts on the fan blades. In addition, this paper utilized an implicit–explicit calculation method. The parameters of blade root stress, tip displacement, plastic deformation, and energy were selected to investigate the effects of the time interval and strike position of a bird strike on the dynamic response of and damage to the blades. The results indicated that the position of bird strikes has a more pronounced effect on blade damage compared to the time interval between impacts. Damage to a blade is most severe when the blade root is struck multiple times. Multiple bird strikes may not always lead to a significant increase in maximum blade tip displacement, and may even have a dampening effect.

Quantum computing for several AGV scheduling models

Due to the high degree of automation, automated guided vehicles (AGVs) have been widely used in many scenarios for transportation, and traditional computing power is stretched in large-scale AGV scheduling. In recent years, quantum computing has shown incomparable performance advantages in solving specific problems, especially Combinatorial optimization problem. In this paper, quantum computing technology is introduced into the study of the AGV scheduling problem. Additionally two types of quadratic unconstrained binary optimisation (QUBO) models suitable for different scheduling objectives are constructed, and the scheduling scheme is coded into the ground state of Hamiltonian operator, and the problem is solved by using optical coherent Ising machine (CIM). The experimental results show that compared with the traditional calculation method, the optical quantum computer can save 92% computation time on average. It has great application potential.

Research on the theory and method of reduced-hole blasting for large cross-section tunnel based on explosive energy dissipation

The traditional tunnel drilling and blasting method places cut holes at the lower center of the excavation face, resulting in an excessive number of blasting holes. With the continuous increase in cross-section area, this design concept can no longer meet the requirements of safe and efficient tunnel boring for large cross-section tunnels. This paper puts forward the theory and method of reduced-hole blasting for large cross-section tunnels, as an alternative to the traditional drilling and blasting method of the “more holes, less charge” design concept. Based on the explosion energy dissipation law and rock’s critical crushing energy dissipation characteristics, the calculation method of the extrapolation distance of the wedge-cut holes is given. The optimum extrapolation distance of the wedge-cut holes was verified using numerical simulation and field tests. The results show that the number of drilling holes can be reduced by about 15.8% using the theory and method proposed in this paper, and at the same time, the damage of retained rock can be effectively controlled. The results of this study can provide a reference for the design of blast network parameters for similar large cross-section tunnels.

Recent Advances in Carbon Nitride Supported Single‐Atom Catalysts: Synthesis, Characterization, and Applications for CO2 Photoreduction

AbstractPhotoreduction of CO2 into value‐added chemicals and fuels is a promising green technology for solar‐to‐chemical conversion. Owing to the atomic utilization, unique metal‐support interaction, and unsaturated coordination active sites, single‐atom catalysts (SACs) have been attracting great attention in achieving high activity and selectivity of CO2 photoreduction reactions. On the other hand, carbon nitride (C3N4) with abundant periodically unsaturated coordination of nitrogen atoms can serve as an excellent support for anchoring metal single atoms. In this context, extensive research efforts have been paid in C3N4‐based SACs for CO2 photoreduction in recent years. In this review, we report the recent advances in C3N4 supported SACs for CO2 photoreduction. We start from the introduction of synthetic strategies of various C3N4 supported metal SACs. Secondly, the main advanced characterization techniques and calculation methods for identifying the single‐atoms and their coordination environments of C3N4‐based SACs are summarized. Thirdly, some state‐of‐the‐art works on the rational design of C3N4‐based SACs and their applications in CO2 photoreduction are introduced. Lastly, we briefly summarize the main challenges and propose important perspectives of C3N4‐based SACs in CO2 photoreduction. This review is expected to provide some useful guidelines for the development of efficient and stable C3N4‐based SACs for CO2 photoreduction.

New chatGPT 3.5 Instruction (Prompt) to Calculate Statistical Indicators for Student Graduation Projects

The paper aims to develop a new chatGPT 3.5 instruction (prompt) for computing statistical indicators in student graduation projects. A bibliometric analysis of 79606 sources published in the Scopus database revealed a high level of interest in solving problems related to "graduation projects" and "statistical indicators." Numerous studies emphasize the importance of probability and statistics education. Concurrently, educators are advised to abandon teaching manual calculation methods to students. ChatGPT could serve as a modern tool for computing statistical indicators. Modern methods employed in this research included reviewing scientific literature, analysis and synthesis, bibliometric analysis, mathematical modeling, computation of statistical indicators, and verification of statistical hypotheses using Z-statistics. Five examples of calculating statistical indicators are provided in this paper. Three tools were used for computing statistical indicators, with the new chatGPT 3.5 instruction (prompt) serving as the experimental method, while Excel tables and Windows calculator were used as control methods. Verification of statistical hypotheses using Z-statistics demonstrated the equality of results between experimental and control methods. The standard testing level was set at α = 0.05. The novelty of this work lies in the creation of the new chatGPT 3.5 instruction (prompt) for computing statistical indicators in student graduation projects. Additionally, a User's Guide has been published. The practical value of this work lies in reducing the time and simplifying the method for computing statistical indicators in preparing graduation projects, as well as in improving their quality. An additional benefit is the expanded use of computers for educational purposes.

A novel stochastic power flow calculation and optimal control method for microgrid based on multivariate stochastic factors fusion – Sensitivity

The stochasticity of power flow of distributed generations (DGs) and load in the microgrid has great influence on power flow distribution and voltage quality of the distribution network. For improving the voltage quality of the distribution network, the questions need to be further studied, which include the description of the stochasticity of the power flow in the microgrid and the impact of the microgrid into the distribution network on the power flow. Therefore, a novel stochastic power flow calculation and optimal control method for the microgrid based on multivariate stochastic factors fusion-sensitivity (MSFF-sensitivity) is proposed in this paper. Firstly, the multivariate stochastic factors fusion (MSFF) function is developed by using the probability density function to extract the stochasticity and correlation of power flow among different stochastic factors in the microgrid, which are effectively unified. Furthermore, the fusion-sensitivity (F-sensitivity) of the power flow in the microgrid integrated into the distribution network is constructed to accurately characterize the influence degree of various stochastic factors in the microgrid on the power flow of the distribution network. Based on this, the output power of the stochastic factor is adjusted to optimally control the power flow of the distribution network. Finally, the algorithm verification suggests that, compared with the conventional power flow methods, the method proposed in this paper is more suitable for the microgrid. The influence of stochastic power flow on the distribution network can be effectively reduced and the voltage quality of the distribution network can be improved by optimizing control of the power flow in the microgrid integrated into the distribution network.

Drug–target interaction prediction based on improved heterogeneous graph representation learning and feature projection classification

Drug–target interaction (DTI) identification is a complex process that is time-consuming, costly and frequently inefficient, with a low success rate, especially with wet-experimental methods. The prediction of DTI by calculational methods is an effective way to solve this problem. However, most existing methods regard drug–target pairs with unknown interaction relationship as negative samples, that the false negative samples will affect the AUC and AUPR evaluation, leading to performance misjudgment. Therefore, in this paper, a new DTI prediction method, DTI-HAN, is proposed to overcome the shortcoming and further improve the predictive performance. In the drug and target feature representation learning stage, this method constructs a drug–target heterogeneous network based on similarity and interaction relationship, and establishes meta-path, node-level and semantic-level bi-attention mechanism. To avoid introducing false negative examples, an improved loss function based only on known edges is proposed. In the DTI prediction stage, feature projection and fuzzy theory are introduced, and membership distribution function is estimated only depended on positive samples. Compared with the DTI prediction methods, DTI-GAT, DTI-GCN and DTI-GraphSAGE, as well as BLM, DTHybrid, SCMLKNN and FPSC-DTI, the experimental results on Enzyme, GPCR, Ion Channel and Nuclear Receptor 4 datasets showed that the DTI-HAN method can greatly improve the AUC and AUPR values on at least 3 datasets to each method. Furthermore, the novel top 100-pair of DTIs prediction were verified by KEGG, DrugBank, ChEMBL and SuperTarget databases, and obtained 21, 48, 61 and 28 validation records, respectively. The top-5 remaining unverified DTIs were performed molecular docking with AutoDock Vina, and the results showed that these drugs and targets have good binding properties. The code and data are available at https://github.com/Yu123456/DTI-HAN.

Robustness of consensus in double‐layer degree positive and negative correlation ring networks

The robustness of consensus in multilayer networks is affected by the network structure, especially the interlayer coupling approach. The article investigates the impact of two interlayer coupling approaches on the robustness of consensus in double‐layer ring networks, where the interlayer relationships are denoted as degree positive correlation (PC) and degree negative correlation (NC), respectively. The robustness of network consensus can be derived from network coherence. Two types of network coherence are first described using the Kirchhoff index and the number of spanning trees, providing a new calculation method for network coherence. The number of network nodes and the coupling strength have been shown to impact the coherence of the two types of networks. Combined with numerical simulation experiments, the NC model shows better consensus than the PC model under the same parameter set. In particular, the parameter values when the network consensus is optimal are obtained.

Research on multi‐mechanism synergistic effects of gas cross‐scale percolation in tight gas reservoirs of Yanchang oilfield

AbstractRevealing the gas transport patterns at the microscale and nanoscale is of great scientific and engineering significance for unconventional oil and gas exploration and development. This paper first systematically analyzes the properties of gas transport mechanism under different Knudsen number conditions. Second, the coupling modes of the cross‐scale multi‐drive mechanism are systematically categorized, and three typical coupling calculation methods are pointed out. Again, the rationality of the cross‐scale multi‐agency coupling is quantitatively calculated. The results show that (a) Under the influence of Fick's diffusion equation, when Knr > 0, the coupled ‘slip flow–Fick diffusion–Knudsen diffusion’ equation does not converge to the Knudson diffusion equation. (b) The ‘Fick diffusion–Knudsen diffusion’ coupled equation is calculated to be more than 102 times as large as the Knudsen diffusion equation.

An analytical calculation method of SiC MOSFET junction temperature based on thermal network theory and Laplace transform

An analytical calculation method of SiC MOSFET junction temperature based on thermal network theory and Laplace transform

Numerical investigation of flow characteristics in the front and rear chambers of centrifugal pump and pump as turbine

To investigate the flow characteristics in front chamber and rear chamber in pump mode and pump as turbine mode, a 3D computational model of a centrifugal pump was established, including the front and rear chamber. Based on Realizable k-ε turbulence model, numerical calculations of incompressible flow were carried out for internal viscous flow in two operating modes. Further analysis was conducted on the flow stability and hydraulic losses under two modes using energy gradient theory and entropy production theory. The numerical simulation results are within reasonable error compared to the experimental results in pump operation mode, which ensures the reliability of the numerical calculation method. The results indicate that the volumetric efficiency in both two modes is on an upward trend with increasing flow, but the volumetric efficiency of the pump mode is more significantly affected by changes in flow; the distribution patterns of dimensionless circumferential velocity and dimensionless radial velocity in the front and rear chambers under two operating modes are similar, but the distribution pattern of dimensionless radial velocity in the front chamber in turbine mode is significantly different from other operating conditions; flow instability is most likely to occur at the outlet of impeller, and the energy loss in clearance of wear-rings is greater than that in the pump chamber.