Traditional Calculation Method Research Articles

Research on Database Construction and Calculation of Building Carbon Emissions Based on BIM General Data Framework

China is entering a new era characterized by carbon peaking and carbon neutrality, and the construction industry, which accounts for a high proportion of social carbon emissions, urgently needs a method to calculate and predict building carbon emissions in advance. This study proposes a method for calculating the life cycle carbon emissions (LCCEs) of buildings based on building information modeling (BIM) technology. The method uses a BIM universal data framework to establish a building carbon emission calculation model and a building carbon emission factor database instance. Taking prefabricated construction projects as an example, it is compared with the traditional calculation method. The results show that the method can more accurately predict building carbon emissions and provide methods and a basis for the construction industry to control carbon emissions in advance.

Rebound Calculation for Deep Excavation in Soft Soil Based on Rebound-Recompression Method

The excavation-induced stress relief and inward movement of the retaining wall will result in soil rebound deformation at the bottom of the excavation, adversely affecting nearby existing tunnels and foundation piles. Various existing methods for calculating the excavation rebound rely on rebound parameters and void ratio obtained from laboratory tests, with considering the effects of sampling, specimen preparation and laboratory procedures on the rebound parameters. As a result, a novel method is proposed in this article for calculating excavation rebound based on rebound-recompression method (RRM). This method first modifies initial void ratio (e0) and laboratory recompression index (CLR) used in traditional methods (TM) for calculation, based on field rebound and recompression curve proposed by the RRM, to in situ void ratio (ev0) and field recompression index (CFR). Then, the final rebound at the bottom of the excavation is calculated using a layered summation method. In addition, through two engineering examples, the proposed method is compared with existing calculation methods and measurements, demonstrating that this method is easy of calculate, yields reliable results, and can accurately predict the final soil rebound at the bottom of the excavation.

Study on the Dynamic Characteristics of Tensional Force for Ice Accumulated Overhead Lines Considering Instantaneous Wind Speed

Icing is one of the key factors affecting the security and reliability of power system operation. Ice accumulation on the overhead line (OHL) conductors is often accompanied by strong winds, whose magnitude and direction are varied constantly, which imposes challenges to the on-line monitoring of OHL’s ice load. This paper analyzed the dynamic characteristics of the tensional force for ice accumulated OHLs through both the on-site experiment and the finite element method (FEM). The correlation between the instantaneous wind speed, the thickness of the accumulated ice and the dynamic tensional force, the aerodynamic resistance coefficient of the conductor, is investigated. It is found that the axial dynamic tension at the end of the iced conductor is approximately proportional to the square of the instantaneous wind speed. The higher the wind speed, the larger the difference between the static tension and the maximum dynamic tension calculated using the 10-min average wind speed. Under the conditions of the example in this article (crescent-shaped icing), when the average wind speed is 20 m/s, the ratio of the difference to static tension is 11.19%. These conclusions are verified with the computational fluid dynamic (CFD) simulation, the same correlation is identified in comparison with the experiments. Due to the fact that the magnitudes of tensional force and vibration are determined by the instantaneous wind speed, significant error exists within traditional calculation methods where average wind speed is used instead.

Nonlinear excitation and mesh characteristics model for spiral bevel gears

Accurate and rapid calculation of nonlinear excitation (NE) and loaded mesh characteristics (LMC) of gear pairs is a key to achieving rapid iterative optimization of gear system designs. Therefore, an analytical model (AM) was proposed for the accurate and numerically efficient calculation of NE and LMC for application to spiral bevel gears (SBG). First, a tooth contact analysis of an SBG was completed using Coons surface technology and mesh theory to determine the contact path and unloaded transmission error (UTE). Thus, an AM for the principal and relative normal curvatures of the SBG was derived using the Euler's formula. Based on the traditional calculation method for a Hertz contact ellipse, the relation between the relative curvatures was introduced to derive the formulas for the major and minor axes using the Muller's method, which could improve the programmability and avoid numerical instability of the program. Then, analytical models for the contact ellipse and pressure distribution on the contact tooth surfaces were derived using the Hertz model and geometric theory. Subsequently, based on a single tooth LMC, infinitesimal method, elasticity, and series stiffness model, a single mesh stiffness (SMS) model for SBGs was developed, which incorporates transverse tooth stiffness, transverse gear foundation stiffness, axial tooth stiffness, axial gear foundation stiffness, and Hertz nonlinear contact stiffness. Based on the SMS and UTE, compliance and load matrices were established, and the time-varying mesh stiffness, loaded transmission error, mesh force, and multi-tooth LMC models of the SBG were determined. Finally, the proposed method was validated against nonlinear FE simulations using examples. Compared to FE simulations, the proposed method requires significantly less computational effort and can be further extended to optimization or system analysis problems.

Self-shrouded torsional blade model equivalence and blade vibration response analysis

In steam turbines, the operation of turbine blades can lead to vibrations, which may result in turbine accidents. Traditional calculation methods are difficult to use due to the complex structure of the torsional blade, and simulation analysis can be time-consuming. Therefore, it is necessary to use the equivalent model instead. Most of the previous studies have simplified the straight blade to a cantilever beam model without considering the shear effect, and used harmonic response analysis to study the vibration of the blade for simulation. The blade body of the torsional blade can be regarded as a torsional variable section beam, and the Timoshenko beam model is the same as the variable section beam. Therefore, the Timoshenko beam model can be regarded as the equivalent of the sheathed torsional blade. Considering the complexity of the calculation of the self-shrouded torsional blade model. According to the theory of Timoshenko beam, the model of the shrouded blade of Timoshenko beam with different torsion angles was established. The first sixth-order modes of the blade model and the vibration response of the adjacent blades under forced vibration are compared, respectively. The results show that the results obtained from the Timoshenko beam blade model considering the torsion angle are closer to the torsional blade model. In addition, the blade vibration response of the same model under different excitation force amplitudes was further compared, and the results showed that the vibration amplitude, acceleration and velocity of the shrouded blade increased with the increase of the excitation force amplitude. However, the magnitude of the inter-shroud collision force and the number of collisions between adjacent blade shrouds are non-linearly related to the amplitude of the excitation force.

An efficient calculation method of large-region dynamic traffic noise maps based on hybrid modeling

The construction of noise maps is of great significance for the management and control of urban noise and the protection of residents’ physical and mental health. The European Noise Directive recommends using computational methods to construct strategic noise maps when possible. The current noise maps based on model calculation rely on complex noise emission and propagation models, and their huge number of regional grids needs to consume a lot of calculation time. This seriously restricts the update efficiency of noise maps, making it difficult to realize large-scale application and real-time dynamic update of noise maps. In order to improve the computational efficiency of noise maps, based on big data-driven technology, this paper combines the traditional CNOSSOS-EU noise emission modeling method with the multivariate nonlinear regression modeling method, and proposes an efficient calculation method of large-region dynamic traffic noise maps based on hybrid modeling method. First, this paper constructs the (daily and nightly) noise contribution prediction models of road sources with different classes, considering the daily and nightly periods and different urban road classes. Parameters of the proposed model are evaluated by using the multivariate nonlinear regression method to replace the complex nonlinear acoustic mechanism modeling. On this basis, in order to further improve the computational efficiency, noise contribution attenuations of the constructed models are parameterized and evaluated quantitatively. And then, the database containing the index table of the road noise sources-receivers and the corresponding noise contribution attenuations is constructed. The experimental results show that compared with the traditional calculation methods based on acoustic mechanism model, the noise map calculation method based on hybrid model proposed in this paper greatly reduces the model computations of noise map, improves the efficiency of noise mapping. It will provide technical support for constructing dynamic noise maps of large urban regions.

Theoretical and experimental analysis of the temperature rise of a ball screw

The temperature rise of a ball screw is the main factor affecting machining accuracy. The traditional methods of calculation and analysis carry out coefficient fitting of known experimental data or using the formula for a friction heat source in bearing theory. However, the screw raceway parameters are ignored in the model. The variation in friction torque with temperature is not considered in the model, so it cannot be effectively applied to engineering. In this paper, the friction heat equation of the ball screw is established theoretically with the screw raceway parameter, and the friction torque is considered with the effect of temperature. A mathematical model of steady temperature and stable time is established for the effective heat source stroke section of the screw, and the temperature rise curve of the screw is fitted. The friction is divided into Coulomb friction torque and viscous friction torque. The viscosity affects viscous friction torque at low temperatures, so the variation in friction torque should be considered when calculating the temperature rise. When a specific temperature is reached, the viscous friction torque has little effect on the overall friction torque; then the ratio of temperature rises at different rotational speeds has an exponential relationship with the ratio of those speeds. The screw stability time decreases with increasing rotational speed. Twelve groups of tests are conducted to verify the theoretical analysis using two samples, two lubricating media, and three speeds. The experimental results agree well with the theory. This proves that the approach can be applied to engineering practice.

The Phasor Diagram of a Superconducting Synchronous Electrical Machine

This paper describes a universal method proposed by the author for the evaluative analytical calculation of the main parameters of synchronous electrical machines, including superconducting ones. Traditional methods for analytical calculation of parameters to build a phasor diagram of electrical machines require a calculation of all dimensions of the active zone, tooth-slot zone and frontal parts of armature windings. All sizes and local states of magnetic circuit saturation are necessary for the calculation of magnetic conductivities. Traditional analytical methods use, among other things, empirical formulas and non-physical coefficients and allow one to calculate only standard machines with classic tooth-slot zones and armature winding types. As a result of drawing a phasor diagram using traditional methods, the angle between the electromotive force and voltage is calculated, which is the machine’s internal parameter and has no major significance for users. The application of modern computer programs for simulation requires a preliminary analytical calculation in order to obtain all dimensions of the three-dimensional model. FEM simulation programs are expensive, require expensive high-performance computers and highly paid skilled personnel. Fast analytical techniques are also required to assess the correctness of the obtained automatic computer simulation results. The proposed analytical method makes it possible to quickly obtain all the main parameters of a newly designed machine (including superconducting ones and those of non-traditional design) without a detailed calculation of the dimensions of the tooth-slot zone and armature end-windings. The characteristic values of load angles are set according to the results of simple calculations, and the desired values, obtained via plotting, represent the inductive resistances of armature winding and inductive voltage drop across it. Results of practical significance, calculated from the voltage diagram, are as follows: the inductor’s magnetomotive force necessary to maintain the nominal load voltage value, regardless of the magnitude (including double overload) and type of the connected load, or the main dimensions of the active zone.

Evaluation of Two Surface Renewal Methods for Calculating the Sensible Heat Flux over a Tea Field Ecosystem in Hilly Terrain

Seasonal drought happens frequently in the lower slope hilly areas of China, which leads to a huge economic loss to China’s famous tea production. An accurate determination of the evapotranspiration (ET) value of different seasons can provide a crucial decision parameter for irrigation management. The surface renewal (SR) method is an accurate and inexpensive method compared with the eddy covariance (EC) method, which is widely used to calculate the sensible heat flux (H). The latent heat flux (LE) evapotranspiration can be estimated indirectly when combined with the energy–balance equation. This research investigated the traditional and improved calculation methods of H (SRsnyder and SRchen), based on the surface renewal theory, over a tea field for one year. The calculation accuracy was obtained from the statistical analysis between the SR and EC methods. Different months’ applicability was evaluated to determine the best calculation method for the tea field. The traditional calculation method (SRsnyder) is based on the van slope model using the second, third, and fifth structure function. The improved SR model (SRchen) introduces a third order temperature function and friction velocity for calculation. The results indicate that SRchen shows a good calculation accuracy of H in the spring seasons (February to April), summer (May to July), and autumn (August to October). The determination coefficients of regression analysis (R2) ranges were [0.66, 0.88] with most values greater than 0.8. The root mean square error (RMSE) ranges were [34.15, 69.22] W/m2. However, during this period, SRsnyder had a poor calculation accuracy of H, and the range of R2 was [0.45, 0.74] with the RMSE ranges of [32.28, 63.25] W/m2. In the winter (November to January), the calculation accuracy of both models was relatively low with R2 almost 30% lower than that of other seasons. Therefore, this study suggests the use of the SRchen method to estimate the H of a tea field ecosystem in the low slope hilly area of the Yangtze River region in the spring, summer, and autumn. While in the winter, the SRsnyder method is recommended.

Estimation of the Effective Irradiance and Bifacial Gain for PV Arrays Using the Maximum Power Current

Bifacial photovoltaic modules are able to convert the solar radiation reaching their front and rear sides, which means that more electricity can be produced using the same array area as monofacial modules with similar ratings. In some locations, the cost per power unit for such a technology has already become cost-competitive with conventional monofacial modules. The so-called effective irradiance and the bifacial gain are useful metrics, respectively, to assess the solar resource and the performance of bifacial arrays. To calculate the effective irradiance, studies previously published employ rear-side irradiance measurements, whereas to compute the bifacial gain, other works make use of monofacial modules with rating similar to those of the bifacial modules under analysis. In this article, a straightforward method is presented, allowing to calculate the effective irradiance from the maximum power current, and to calculate the bifacial gain using a power scaling relation. The proposed method was experimentally tested using an outdoor platform with a dual-axis tracking system with bifacial modules. The effective irradiance was calculated using the novel method presented nRMSE of 2.88%, relative to the results obtained using the consolidated method. The bifacial gains obtained were 6.24% and 6.69%, respectively, using the proposed and traditional calculation methods. The procedure presented in this study might be useful for the quantification of the effective irradiance and the bifacial gain for PV installations, which do not have extensive monitoring hardware.

Research on thickness problem of pavement asphalt layer based on energy dissipation

Aiming at the problems of low calculation accuracy and poor calculation effect of the traditional calculation method of the optimal thickness of pavement asphalt, a thickness calculation method of pavement asphalt layer based on energy dissipation was proposed. First, according to the energy dissipation theory, the changes of pavement in creep deformation zone and plastic damage zone under different temperature conditions were concretely analyzed, which laid the foundation for subsequent research. Then, proposing to take the lowest energy dissipation control of asphalt pavement as the principle, the energy consumption of asphalt layer was proposed and the optimal thickness of asphalt layer was calculated under the premise of considering the environment and other parameters. Finally, the method was verified by analyzing the changing conditions of the actual failure zone. The verification results show that when the thickness of the asphalt layer reaches the optimal thickness, the main creep deformation zone in the asphalt layer does not change significantly, and the scope of the actual plastic failure zone will be reduced to the minimum. At this time, the energy dissipation of pavement is the lowest, which conforms to the principle that the energy dissipation of the pavement is controlled at the lowest. Moreover, by analyzing the peak value of plastic dissipated energy and the changing situation of the actual plastic failure zone, it is concluded that the most suitable thickness range of asphalt layer is 10 cm∼20 cm. Therefore, through the research of the above, the amount of asphalt used is greatly reduced, and the energy consumption is reduced.

Numerical Simulation of Failure Behavior of Reinforced Concrete Shear Walls by a Micropolar Peridynamic Model.

A reinforced concrete shear wall is an important building structure. Once damage occurs, it not only causes great losses to various properties but also seriously endangers people's lives. It is difficult to achieve an accurate description of the damage process using the traditional numerical calculation method, which is based on the continuous medium theory. Its bottleneck lies in the crack-induced discontinuity, whereas the adopted numerical analysis method has the continuity requirement. The peridynamic theory can solve discontinuity problems and analyze material damage processes during crack expansion. In this paper, the quasi-static failure and impact failure of shear walls are simulated by improved micropolar peridynamics, which provides the whole process of microdefect growth, damage accumulation, crack initiation, and propagation. The peridynamic predictions are in good match with the current experiment observations, filling the gap of shear wall failure behavior in existing research.

Automatic Dynamic User Allocation with opportunistic routing over vehicles network for Intelligent Transport System

Dynamic auto node configuration with Adhoc features is an advanced concept for vehicle communication. It is the modern internet-based data transmission in Intelligent Transport Systems. Different node auto-configuration schemas and node address-related approaches were used to improve network infrastructure and robust data communication between vehicles in Transport Intelligence-based wireless vehicle Adhoc networks. To address the problem of vehicle node auto-configuration with reduction of delay in transmission is an emerging research concept in data forwarding between vehicles in Adhoc networks, so this paper proposes an Automatic Dynamic User Allocation based Data Forwarding with Opportunistic Routing (ADUADFOR) approach with the assistance of mobility of vehicle association concerning the forwarding of data between vehicles in Adhoc networks. In this approach, each vehicle node carries a replica of other vehicle information, which decides the route based on this collective dynamic information of vehicles. Extensive simulated results of the proposed approach give better performance to improve Quality of service (QoS) through decreased overhead when compared to traditional mobility-based routing calculation methods in vehicle Adhoc networks.

Thermal Elastohydrodynamic Lubrication of Herringbone Gear Considering the Effect of Oil Gas Mixture

AbstractIn order to analyze the dynamic behavior of the oil film in the herringbone gear meshing area under oil injection lubrication conditions more accurately, this paper proposed a thermal elastohydrodynamic lubrication (TEHL) analysis method, by combining the traditional TEHL calculation method with two-phase flow theory. First, ansys/cfx 18.1 was used to determine the air content of the lubricating oil in the meshing zone under the injection condition. Then, considering the influence of air content on the rheological properties of lubricating oil, the traditional TEHL model was improved. On this basis, the influence of injection angle α1 on the oil fraction and the lubrication characteristics of the oil film were analyzed. This research can provide a feasible method for the analysis of the lubrication characteristics of herringbone gear.

Research on Magnetic-Induced Error of Small-Sized Fiber Optic Gyro Fiber Coil in Space Environment

Spacecraft is severely limited in weight and volume, resulting in a small bending radius of the fiber coil used by IFOG (Interference Fiber Optic Gyroscope). The fiber coil has such a size that the influence of bending on fiber birefringence cannot be ignored. In this paper, we research magnetic-induced errors of small-sized IFOG working in low orbit space. Firstly, we use the Jones matrix to analyze the effects of radial magnetic field and axial magnetic field on IFOG. Secondly, we establish a three-dimensional model for the radial magnetic-induced errors and magnetic-induced errors of minor radius fiber coil. Using the finite element method, we analyze the magnetic-induced error between different levels of the fiber coil. Combined with the birefringence distribution of the minor radius fiber coil, an accurate three-dimensional magnetic-induced error model is established. Thirdly, in the experiment, we design the magnetic-induced error test platform that includes the Fluke standard current source, transconductance amplifier, and Helmholtz coil. The experimental results show that, compared with the traditional calculation method, the three-dimensional magnetic-induced error model reduces the RMSE (Root Mean Square Error) of the radial magnetic field by 56.9% and the RMSE of the axial magnetic field by 35.7%, respectively.

Refined Calculation of Multi-Objective Ecological Flow in Rivers, North China

The concepts and calculation of basic, suitable, and fine ecological flow are put forward, and an integrated multi-method to calculate the ecological flow in rivers under multi-objectives is explored. Based on this, a refined calculation theory and method of a multi-objective ecological flow division based on time and space is proposed. That is, three commonly used methods, namely, the hydrology method, the hydraulics method, and the habitat method, are selected to finely calculate the ecological flow demand at different periods, in different sections, and under different ecological objectives. This approach breaks through the traditional ecological water demand calculation method based on hydrology and develops a river ecological flow calculation method based on water environmental protection objectives. A refined calculation method of ecological flow division based on time and space is developed to ensure that the ecological-hydrological process in rivers and lakes meets the ecological flow demand in different periods, different reaches, and different ecological objectives. Taking eight rivers entering Baiyangdian Lake as an example, the ecological flow demand in different river sections under different ecological objectives at different times is calculated to ensure the ecological flow process. The results show that the range of basic ecological flow demand range is 0.07–3.87 m3/s, the range of suitable ecological flow demand is 0.51~10.74 m3/s, and the range of fine ecological flow demand is 0.71~20.29 m3/s. In terms of spatial distribution, Ping River has the lowest demand for ecological flow, and the Zhulong River has the largest. In terms of the interannual ecological demand, those of the Baigou River, Fu River, Xiaoyi River, and Zhulong River are larger. In the demand process across the year, the demand is the largest from July to September, while the demand is the smallest from March to May. Similarly, most rivers face such problems as a sharp decline in runoff, drying up of the river, and an urgent need to restore ecology in northern China. This study also has insights and reference significance for other regions.

Study on Calculation Method of Stability of Damaged Sliding Dangerous Rock on Reservoir Bank

The rapid destruction of dangerous rock produces a large amount of energy, causing heavy casualties and economic losses every year. There are various failure modes and stability calculation methods of dangerous rock. The common failure modes of dangerous rock are tipping mode, sliding mode and falling mode. For large tower pillar dangerous rock with degraded foundation, it is unreasonable to use conventional stability calculation methods to calculate the stability of dangerous rock. This paper takes Jianchuandong dangerous rock in Wushan County as the research background, considering the expansion of rock cavity of damaged dangerous rock base and the deterioration of rock mass in the base of large tower column reservoir bank, and establishes the stability calculation method of dangerous rock suitable for the damage deterioration of the base. It is innovative on the basis of the traditional stability calculation method of dangerous rock, which has important practical significance and theoretical basis for the calculation of the stability of unconventional dangerous rock.

An improved carbon emission calculation framework of precast concrete column in construction stage based on LCA

ABSTRACT The abundant carbon emissions generated by the construction industry have gradually become a significant problem. Rather than employing traditional construction methods, the industrialized building system adopts the efficient on-site assembly of prefabricated components, which provides a new solution for reducing industry carbon emissions. Currently, great differences exist in the life cycle assessment schemes for prefabricated buildings and components, which requires considering many different factors. The accuracy and applicability of the results must therefore be improved. In this study, an improved life cycle calculation framework is proposed to assess the carbon emissions of prefabricated concrete columns in the construction stage. Based on the commonly used calculation methods of carbon emission factors, the framework uses a new calculation method with more considerations for vehicle transportation and uses the consumer lifestyle method to estimate construction workers’ carbon emissions. The framework also fully considers the loss of components in the transportation process. The calculated results are compared with the traditional carbon emission factor calculation methods. Overall, the results for the framework are relatively significant because they more comprehensively consider various factors when compared to results using the traditional calculation methods.

Dynamic Simulation Study on Water-Supply Volume of the Hanjiang-to-Weihe River Water Diversion Project

The calculation of water supply is affected by many factors, such as water requirements, water-supply capacity, etc., which change with time and the environment. The traditional calculation methods are generally used under several fixed operating situations. The scenarios are too few to cover the various situations encountered in actual operations and take insufficient account of boundary conditions, such as reservoir inflow, water requirements, etc. The water-supply schemes facilitated by these methods are finite and not adaptable to the ever-changing, producing environment. Therefore, based on a traditional water supply-demand balance analysis, this study established a dynamic calculation model that takes into account different variables, such as reservoir inflow, ecological flow, and water demand. This study also constructed a dynamic simulation system based on the comprehensive, integrated platform and dynamic calculation model, which shortens the calculation period from a month to a day. The results show that the water-supply assurance rates calculated under different conditions reach higher than 93.9% for domestic and production, and higher than 50.9% for agriculture, which all exceed the design assurance rates. Additionally, the dynamic calculation model can significantly improve the calculation efficiency, playing an important role in the formulation of the project-operation plan and project-benefit evaluation.

Integrating Subjective–Objective Weights Consideration and a Combined Compromise Solution Method for Handling Supplier Selection Issues

The development of artificial intelligence and the recent COVID-19 pandemic as well as the emergence of other diseases has led to dramatic changes in the overall supply chain development. The choice of a suitable supplier will be the key to ensuring sustainable development of the company and the normal operation of the overall supply chain. However, the evaluation data of the supplier selection contains both qualitative and quantitative data simultaneously. In addition, the evaluation information provided by experts often includes some incomplete and hesitant information. These reasons lead to the complexity of supplier selection. Traditional supplier selection calculation methods ignore the objective weight considerations and thus lead to biased assessment results. The main goal of this study is to overcome the limitations of conventional supplier selection methods, fully consider the subjective and objective weights of the evaluation criteria and deal with incomplete information for providing more correct supplier ranking results. A stepwise weight assessment ratio analysis (SWARA) method, the 2-tuple linguistic representation method, and the combined compromise solution (CoCoSo) were applied in this study to solve the problem of supplier selection. To verify the rationality and correctness of the proposed method, the third-party logistics supplier selection was used as the illustrated example in the numerical validation section. The simulation results confirm that the proposed method can effectively deal with supplier selection with unclear information and can provide more reasonable supplier ranking results.