Dynamic Calculation Method Research Articles

Dynamic Modeling of Angular Contact Ball Bearing with Local Defects under EHL Considering Impact Force

In order to analyze the operating status of angular contact ball bearings(ACBBs) with local defects in more detail, a dynamic model of ACBB with local defects considering impact force under elastohydrodynamic lubrication conditions is proposed. Firstly, an elastohydrodynamic lubrication model for defective bearings considering spin is established, the film thickness and film stiffness of the defective bearings are calculated, and then time-varying displacement excitation model and time-varying stiffness model for local defects in angular contact ball bearings is presented. Based on this, an instantaneous impact force function related to defect size and bearing speed is established. Secondly, based on Hertz contact theory and impact force function, a dynamic calculation method for ACBBs with local defects on the outer ring is proposed. Finally, the vibration characteristics of ball bearings with faults are investigated, and the influence of different parameters on the dynamic response of the bearings is analyzed. The calculation results show that under lubrication conditions, the impact force on the vibration of the bearing is significantly weakened. With the increase of defect size and load, the frequency of bearing fault characteristics remain unchanged, but its amplitude increases. As the bearing speed increases, the characteristic frequency and amplitude of bearing faults increase.

Study of the Dynamic Adaptive Calculation Method for River Water Environmental Capacity

Controlling the total amount of river pollutant discharge is an important means of water resource protection and management, and it is also a necessary condition for ensuring the normal functioning of water areas. The total amount of pollutant discharge is closely related to the water environmental capacity (WEC). Shifting from the traditional method of calculating WEC to dynamic analyses and calculations, concerning practical applications, in this paper, a dynamic adaptive calculation method is proposed for the river WEC that considers the changes in adaptive demand and hydrological conditions. In this method, the dynamic WEC is represented by intervals based on dynamic changes in different spatial and temporal scales, various calculation methods, hydrological conditions, and parameters. According to the calculation results for the WEC, a variable interval was formed. Taking the Shaanxi section of the main stream of the Wei River as the research object, with the support of an integrated platform, the dynamic adaptive calculation of the WEC in the Shaanxi section of the Wei River was realized, and a corresponding simulation system was constructed. The verification results show that (1) the dynamic calculation of WEC can be realized by freely combining different model methods and calculation conditions; (2) the WEC is described using a variable interval, which has strong applicability and operability; and (3) the simulation system can quickly adapt to the changing needs of practical applications and provide managers with visual and credible decision support. The research results provide a theoretical basis for river water environment pollution prevention and environmental management decision-making and help in the high-quality development of the river basin.

Dynamic Behavior of Rubber Fiber-Reinforced Expansive Soil under Repeated Freeze–Thaw Cycles

Large volumes of waste tires are generated due to the rapid growth of the transportation industry. An effective method of recycling waste tires is needed. Using rubber from tires to improve problematic soils has become a research topic. In this paper, the dynamic response of rubber fiber-reinforced expansive soil under freeze–thaw cycles is investigated. Dynamic triaxial tests were carried out on rubber fiber-reinforced expansive soil subjected to freeze–thaw cycles. The results showed that with the increase in the number of freeze–thaw cycles, the dynamic stress amplitude and dynamic elastic modulus of rubber fiber-reinforced expansive soils first decrease and then increase, and the damping ratio first increases and then decreases, all of which reach the turning point at the 6th freeze–thaw cycle. The dynamic stress amplitude and dynamic elastic modulus decreased by 59.4% and 52.2%, respectively, while the damping ratio increased by 99.8% at the 6th freeze–thaw cycle. The linear visco-elastic model was employed to describe the hysteretic curve of rubber fiber-reinforced expansive soil. The elastic modulus of the linear elastic element and the viscosity coefficient of the linear viscous element first decrease and then increase with the increase in the number of freeze–thaw cycles; all reach the minimum value at the 6th freeze–thaw cycle. The dynamic stress–dynamic strain curve calculation method is established based on the hyperbolic model and linear visco-elastic model, and the verification shows that the effect is better. The research findings provide guidance for the improvement of expansive soil in seasonally frozen regions.

Optimization and Regulation Method for Large Blade-regulating Pump Stations Considering Safety Constraints

Abstract In plain areas, making flood control and drought resistance a heavy task. Large water pumping stations undertake the important task of water lifting and scheduling. Due to the physical characteristics of large pumping stations, they are often affected by the upstream and downstream water levels during water lifting scheduling, resulting in low head operating conditions. Low head operating conditions can easily cause pumping stations to operate at excessive power, thereby affecting the health of pumping station equipment. Based on the head efficiency curve of a large blade regulating pump station in this article, by optimizing the regulating mathematical model and considering constraints such as water level, flow rate, power, efficiency, and blade angle adjustment time interval under low head conditions, a dynamic programming calculation method is adopted to construct an optimized regulating method for the pump station. Based on real-time water level, various operating data of the unit are optimized to ensure the blade angle, power, and the flow rate and other parameters are all within the safety constraint range. And various operating data could be used to guiding the real-time optimization and adjustment of the pumping station, and additionally providing the operating foundation for the intelligent pumping station.

THE IMPACT OF TUNNEL LINING ON THE REACTION OF THE GROUND SURFACE UNDER THE INFLUENCE OF TRANSPORT LOADS

When a tunnel is subjected to transport loads (loads from the moving transportation within it), vibrations occur in the tunnel lining and the surrounding massif. Traditional quasi-static methods do not account for the dynamic behavior of tunnel structures. Therefore, this paper aims to develop a dynamic calculation method using modern mechanics. The purpose of this paper is to develop such a method. The relevance of the research in this article is due to the trend of increasing the speed of vehicles in recent years. This paper considers an unsupported and lined circular cylindrical shallow tunnel. The tunnel is modeled as an extended circular cylindrical cavity or reinforcing shell located in an elastic half-space. The surface of the cavity or the inner surface of the shell is subjected to a normal load (the effect of the pressure of a moving object on the tunnel) and a tangential load parallel to this axis (the effect of the friction forces of a moving object on the tunnel) moving uniformly along its axis. The motion of the half-space and the shell are described by the dynamic equations of elasticity theory and the equations of classical shell theory, respectively, in moving coordinate systems. The integral Fourier transform method is used to solve the problem. In the case of moving axisymmetric normal and axial tangential loads acting on the tunnel, a numerical study of the influence of the tunnel lining on the stress-strain state of the ground surface is carried out.

Ecological compensation mechanism controlled by both river ecological water demand and regional water rights

River ecological protection and rational utilization of water resources provide an important support for the sustainable development for human beings and nature. In view of the lack of ecological compensation research on river ecological water demand and socio-economic water demand, a mechanism and methodology for ecological compensation based on the synergistic control of river ecological water demand and river water rights allocation is proposed. The variable monthly flow method and the improved dynamic calculation method are applied to obtain the river basic and suitable ecological water demands as the river protection threshold. A two-layer decision model for water rights allocation is established, which realizes the cascading allocation of initial water rights from city to counties to sectors, and the socio-economic water usage threshold for each level is obtained based on the model. Developing compensation discrimination guidelines under the dual-threshold synergistic control and using the unilateral water resources value by sub-sector as the compensation standard, realize the quantification and sharing of compensation funds. The Nanyang section of the Bai River basin in China is used as an example. The ecological compensation value for wet year (2011), normal year (2012), and dry years (2014–2013) are 0, 15.09 × 108 and 12.04 × 108 (average value for dry years) RMB. The adoption of suitable ecological water demand thresholds in 2012 increases the ecological protection requirements thus leading to an internal compensation situation between Nanyang County and Xinye County. From 2014 to 2016, river runoff continued to be low, and excessive water intake from upstream lead to a chain of compensation situations in the midstream and downstream. It is essential to establish a basin and regionally nested ecological compensation mechanism. The research results are conducive to improving the eco-compensation theory and provide scientific references for water resources management and high-quality development in the basin.

A Dynamic Hysteresis-Based Iron Loss Calculation Method and Its Application in a PWM-Fed IPMSM

A Dynamic Hysteresis-Based Iron Loss Calculation Method and Its Application in a PWM-Fed IPMSM

Blasting safety criterion of existing high speed railway tunnel over tunnel

Drilling and blasting method is still an important method in the current tunnel excavation construction. Controlling the vibration effect of blasting during construction and its influence on the upper span tunnel is the key problem in tunnel construction. Based on Chongqing Science City tunnel excavation blasting project, combined with the tunnel blasting vibration monitoring and testing, this paper analyzes the propagation attenuation law of tunnel blasting vibration along the rock mass, and studies the load characteristics of the explosion stress wave propagating to the existing high-speed railway tunnel. Considering the influence of the buried depth of the blasting source, a mathematical prediction model of the attenuation law of the upper span existing high-speed railway tunnel caused by tunnel blasting is established. Based on the dynamic finite element numerical calculation method, the influence of blasting vibration on the structure of the existing high-speed railway tunnel under construction is analyzed, and the propagation and attenuation law of blasting vibration along the tunnel contour is studied. Based on the ultimate tensile stress criterion, the ultimate shear stress criterion and the Mohr criterion, and compared with the results obtained from the numerical simulation, the blasting safety criterion model of the existing high-speed railway tunnel over the tunnel is established.

Analytical calculation method for development dynamics of water-flooding reservoir considering rock and fluid compressibility

The existing development dynamics calculation methods for water-flooding reservoir are difficult to comprehensively consider factors such as injection-production imbalance, irregular well pattern, reservoir heterogeneity and compressibility. Therefore, leveraging reservoir engineering and material balance theory, and considering the influence of reservoir compressibility on reservoir development dynamics, a set of analytical calculation method for development dynamics of water-flooding reservoir considering rock and fluid compressibility water-flooding with clear theories and high computational efficiency were derived and constructed. Based on the oil-water two-phase Darcy law, the reservoir compression coefficient is introduced, and the development dynamics calculation method of a single injection-production unit considering compressibility is derived and established by combining the material balance theory, which can quantitatively describe the relationship between the oil and water production rates per unit. On this basis, the injection-production splitting strategy is introduced, which is extended to the calculation of development dynamics for multiple well groups in the whole reservoir. In this study, seven working conditions with various injection-production ratios were designed to validate the reliability of the new method. Subsequently, the method was applied to actual block for further verification, and the prediction accuracies of oil and water production rates were improved by 67.48% and 19.07%, respectively.

Towards a dynamic flow calculation method based on Schur complement for natural gas network

Towards a dynamic flow calculation method based on Schur complement for natural gas network

Dynamic Calculation Method for Zonal Carbon Emissions in Power Systems Based on the Theory of Production Simulation and Carbon Emission Flow Theory

Power systems are the main source of carbon emissions. Currently, coordinated operation strategies of the source–grid–load–storage model considering carbon emissions is primarily expanded from the generation side. For practical power systems, where multiple types of generating units coexist at a single node, it is difficult to develop unit combination strategies that simultaneously consider carbon emission factors and power flow constraints. Therefore, a new power flow calculation method based on connectivity matrix theory was proposed, aiming to address the issues of existing approaches that are too coarse and unable to accurately represent the operating states of multiple units under each node. Furthermore, a new method for dynamic calculation of regional carbon emission based on connectivity matrix and carbon emissions flow was introduced to improve the accuracy of carbon emission measurements. Firstly, a simulation model for a coordinated optimization operation based on the minimum system cost for the source–grid–load was established and an optimal flow calculation method using a connectivity matrix was introduced. Second, a dynamic carbon emission calculation method, considering electricity sources, was developed by combining the results of the optimal power flow calculation with carbon emission flow theory. Finally, the effectiveness of the approach in this article was verified by the IEEE 14-bus system example and a provincial power grid, ensuring strict adherence to the conservation principle of carbon emissions between the supply and demand sides and satisfying power flow constraints.

Social network group decision-making method based on stochastic multi-criteria acceptability analysis for probabilistic linguistic term sets

In social network group decision-making (SNGDM) problems, decision-makers (DMs) often express their opinions or preferences using probabilistic linguistic term sets (PLTSs). In this paper, a novel SNGDM method for probabilistic linguistic information is proposed. Firstly, to obtain the prioritization of DMs in the clustering process, a DM clustering method for SNGDM is developed considering the influence of trust relationships and opinions similarity among DMs. Then, to satisfy the requirements of the consensus reaching process in SNGDM, a dynamic consensus threshold calculation method based on an optimization model is introduced. Furthermore, in the consensus measure stage, a novel consensus measure method for both DMs and subgroups is proposed, using a stochastic multi-criteria acceptability analysis (SMAA) method. Based on the consensus measure method, a novel SNGDM method based on SMAA for PLTSs is proposed. Finally, a case study of service quality evaluation in institutional pensions is used to illustrate the effectiveness of the proposed method. The results of case show that the proposed method can adjust consensus thresholds dynamically based on each round of collective opinions, and can solve the SNGDM problems when DMs can not provide their preferences for criteria weights.

Energy Potential of Existing Reversible Air-to-Air Heat Pumps for Residential Heating

Heat pumps can be considered one of the key technologies to meet the building stock decarbonization target set by Europe. Especially in warm locations, many households have already incurred costs for the installation of air-to-air heat pumps, but, in most cases, they only use them in summer for cooling, while heating is provided by fuel-fired boilers. For these households, the goal of reducing primary energy consumption could be achieved almost cost-free by using heat pumps, that were installed for summer cooling, also for winter heating. Based on this assumption, this research aimed to evaluate the energy savings and environmental benefits that can be achieved by using air-to-air heat pumps instead of gas boilers as the main heating system, without additional costs except for the installation of electric radiators in bathrooms. To quantify variations in energy, environmental, and economic savings compared to the baseline condition, detailed simulations were conducted with the dynamic hourly calculation method (EN ISO 52016) in six different European locations, considering heat pumps with different efficiencies and two different building types. The analysis showed positive impacts at all sites due to the use of heat pumps, which can lead to primary energy savings ranging from about 20% to about 60%. The results varied according to outdoor climate, coefficient of performance of heat pumps, building type, and, on the economic side, the cost of energy. This research provides useful results for outlining decarbonization scenarios, assuming that heat pumps are one of the technologies needed to meet the EU’s climate neutrality goal.

Calculation method for the dynamic temperature distribution of winding area in dry-type on-board traction transformer

Dry-type on-board traction transformers have attracted considerable attention because of their lightweight and flameproof characteristics. The temperature distribution of winding areas is a critical indicator for representing operation performance. This study developed a calculation model for the dynamic temperature distribution of winding areas in dry-type on-board traction transformers under time-varying environments. First, a dynamic temperature calculation model was proposed based on the principle of thermoelectric analogy. Next, for addressing the transient outlet temperature of air ducts in the model, the influences of environment parameters and air duct size on heat dissipation were investigated, and a calculation model for the transient outlet temperature was proposed. Finally, the validity of the proposed dynamic temperature calculation method was verified experimentally, and the method was compared with conventional computational fluid dynamics numerical simulation using line data. The results revealed that for various structural parameters and time-varying operation scenarios, the proposed method could accurately obtain the temperature distribution in the winding area and could save more than 99% of the time cost compared with the conventional method.© 2017 Elsevier Inc. All rights reserved.

Determination of River Ecological Flow Thresholds and Development of Early Warning Programs Based on Coupled Multiple Hydrological Methods

In order to safeguard the health of river ecosystems and maintain ecological balance, it is essential to rationally allocate water resources. This study utilized continuous runoff data from 1967 to 2020 at the Zhouqu Hydrological Station on the Bailong River. Five hydrological methods, tailored to the hydrological characteristics of the Zhouqu hydrological cross-section, were employed. These methods included the improved dynamic calculation method, the NGPRP method, the improved monthly frequency computation method, the improved RVA method, and the Tennant method. Ecological flow calculations were conducted to determine the ecological flow, with analysis carried out through the degree of satisfaction, economic benefits, and the nonlinear fitting of the GCAS model. We established an ecological flow threshold and early warning program for this specific hydrological cross-section. Ecological flow values calculated using different methods for each month of the year were compared. The improved RVA method and Tennant method resulted in small values ranging from 4.05 to 36.40 m3/s and 7.65 to 22.94 m3/s, respectively, with high satisfaction levels and economic benefits, but not conducive to ecologically sound development. In contrast, the dynamic calculation method, NGPRP method, and improved monthly frequency calculation method yielded larger ecological flow values in the ranges of 21.79–97.02 m3/s, 23.90–137.00 m3/s, and 28.50–126.00 m3/s, respectively, with poor fulfillment and economic benefits. Ecological flow thresholds were determined using the GCAS model, with values ranging from 16.72 to 114.58 m3/s during the abundant water period and from 5.03 to 63.63 m3/s during the dry water period. A three-level ecological warning system was proposed based on these thresholds, with the orange warning level indicating optimal sustainable development capacity for the Zhouqu Hydrological Station. This study provides valuable insights into the scientific management of water resources in the Bailong River Basin to ensure ecological security and promote sustainable development.

Residual stress distribution and relaxation in U-rib full penetration welds by ultrasonic impact treatment

Ultrasonic impact treatment (UIT) as an effective method for alleviating welding residual stresses (WRS) is used to improve the fatigue performance of welded structures. However, its application to single- and double-sided U-rib welds in orthotropic decks has been limited. To address this, an experimental and numerical investigation on WRS and UIT was carried out for different deck thicknesses. A 3D thermo-elastic-plastic approach was employed to model the temperature and stress fields by the ABAQUS software. Additionally, a dynamic explicit calculation method was developed to simulate the UIT process, and its accuracy was verified by comparing the actual and numerical grooves and WRS after UIT. Ultrasonic stress measurement was employed to determine the distribution and magnitude of WRS before and after UIT. The results demonstrate that most relative errors of residual stress numerical and test results under different stress paths after UIT are within 10 %, confirming the reliability and effectiveness of this method. For single-sided U-rib welds after UIT, the reduction in WRS at the weld seam ranges from approximately 25.6 % to 87.4 %, while for double-sided U-rib welds, the reduction varies from about 22.2 % to 65.5 %. The impact of UIT on longitudinal residual stresses is more significant compared to its effect on transverse residual stresses. However, UIT results in a relatively smaller reduction in WRS away from the weld seam. Furthermore, it is observed that altering the deck thickness results in different disparities in WRS outcomes after UIT.

Dynamic response characteristics and damage calculation method of fractured rock mass under blasting disturbance

The mechanical responses and damage characteristics of fractured rock masses under dynamic loads play a significant role in ensuring the safety of blasting operations. The study employs dynamic finite element method (FEM) to simulate blasting in fractured rock masses, revealing the propagation features of blasting stress waves, the evolution of effective stress and the mechanism of damage evolution around the borehole. Based on the Weibull distribution, a rock damage model was established, which yielded the stress-strain relationship and damage equation for rocks under uniaxial impact. The parameters of the damage equation were fitted through numerical SHPB tests. The results indicate that in the direction of higher initial stress, the stress wave propagates faster, and the development of damage surfaces is more pronounced. In cylindrical charge blasting, the maximum blasting stress occurs in the middle section of the borehole, with limited influence from the charge on the bottom of the hole. Within a range of approximately 2 to 3 times the borehole diameter, the surrounding rock sustains complete damage. While within a range of about 4 to 5 times the borehole diameter, the degree of damage to the surrounding rock decreases rapidly, and beyond this range, the damage to the surrounding rock gradually diminishes.

A novel link fabrication attack detection method for low-latency SDN networks

The application of Software-defined Networking (SDN) in low-latency scenarios, such as 6G, has received immense attention. Notably, our research reveals that SDN remains susceptible to link fabrication attacks (LFA) in low-latency environments, where existing detection methods fail to effectively detect LFA. To address this issue, we propose a novel detection method called Correlated Link Verification (CLV). CLV is composed of three phases. Firstly, we introduce a data processing method to mitigate measurement error and enhance robustness. Secondly, we present a multipath transmission simulation method to convert the measured performance disparity between correlated links into statistical features. Thirdly, we propose a dynamic threshold calculation method, which utilizes the statistical features to determine thresholds based on extreme value theory and probability distribution fitting. Finally, CLV identifies the fabricated link within correlated links based on the thresholds and current statistical features. Extensive experiments have been conducted to validate the feasibility, effectiveness, scalability and robustness of CLV. The experimental results demonstrate that CLV can effectively detect LFA in low-latency SDN networks.

Integrating daylight with solar thermal modeling: A dynamic calculation method for complex fenestration systems

This study developed a mathematical model named the DL-E model, which links annual dynamic daylight and solar heat gain calculations for Complex Fenestration Systems (CFSs). The DL-E model utilizes the Klems Bidirectional Scattering Distribution Function (BSDF) to characterize CFSs and can consider the shading effect of obstacles, as well as solar radiation reflected from obstacles and the ground. The DL-E model uses the Perez all-weather model to calculate transmitted solar radiation contributed by diffuse solar radiation, rather than the simplified sky model used in EnergyPlus. Results calculated with the DL-E were compared with those computed with EnergyPlus, and it was found that for most of the results, the both methods yielded closely aligned outcomes. However, for the diffuse transmitted solar radiations, reflected solar radiation from the ground in the case with a vertical obstacle, and the reflected solar radiations from the obstacle, the values calculated with DL-E showed significant differences compared to those calculated with EnergyPlus due to the use of the simplified sky model in EnergyPlus. In contrast, the values calculated with the DL-E model which used the Perez all weather sky model displayed very small difference compared to those calculated with Radiance, which means the values derived with EnergyPlus may produce significant errors. Additionally, a new workflow has been developed for calculating building load and energy for CFSs to avoid the manual conversion of the BSDF files.

The real-time dynamic liquid level calculation method of the sucker rod well based on multi-view features fusion

In the production of the sucker rod well, the dynamic liquid level is important for the production efficiency and safety in the lifting process. It is influenced by multi-source data which need to be combined for the dynamic liquid level real-time calculation. In this paper, the multi-source data are regarded as the different views including the load of the sucker rod and liquid in the wellbore, the image of the dynamometer card and production dynamics parameters. These views can be fused by the multi-branch neural network with special fusion layer. With this method, the features of different views can be extracted by considering the difference of the modality and physical meaning between them. Then, the extraction results which are selected by multinomial sampling can be the input of the fusion layer. During the fusion process, the availability under different views determines whether the views are fused in the fusion layer or not. In this way, not only the correlation between the views can be considered, but also the missing data can be processed automatically. The results have shown that the load and production features fusion (the method proposed in this paper) performs best with the lowest mean absolute error (MAE) 39.63 m, followed by the features concatenation with MAE 42.47 m. They both performed better than only a single view and the lower MAE of the features fusion indicates that its generalization ability is stronger. In contrast, the image feature as a single view contributes little to the accuracy improvement after fused with other views with the highest MAE. When there is data missing in some view, compared with the features concatenation, the multi-view features fusion will not result in the unavailability of a large number of samples. When the missing rate is 10%, 30%, 50% and 80%, the method proposed in this paper can reduce MAE by 5.8, 7, 9.3 and 20.3 m respectively. In general, the multi-view features fusion method proposed in this paper can improve the accuracy obviously and process the missing data effectively, which helps provide technical support for real-time monitoring of the dynamic liquid level in oil fields.