Accurate Calculation Model Research Articles

Establishment and Verification of Nonlinear Bolt Head Connection Stiffness Theoretical Model Based on Levenberg-Marquardt Method

Although some scholars have established the calculation method of bolt head connection characteristics, the method contains fewer influence factors; the calculation accuracy is not high, and the general applicability is limited. Based on the Levenberg Marquardt optimization algorithms, a more accurate calculation model of bolt head connection stiffness is proposed in this article. The model includes many parameters such as bolt head thickness, equivalent diameter, bolt diameter, thickness of connected parts, elastic modulus of bolt and elastic modulus of connected parts. Through the finite-element verification and comparison with the results of the Fears Alkatan method, the calculation results of the bolt head connection stiffness calculation model in this article are effective and accurate, which provides a universal calculation model for calculating the bolt head connection stiffness of various parameters, and fills the shortage of inaccurate calculation of the current theoretical model of bolt head stiffness.

Temperature rise of journal bearing of the high-speed circular arc gear pump

A “circular arc–involute–circular arc” circular arc gear pump was developed based on a gear meshing principle and coordinate transformation as well as an accurate calculation model of the radial force. The dependence of the radial force on the meshing angle was investigated. The temperature rise of journal bearings in the pump was evaluated for bearings with and without herringbone grooves. Furthermore, the influence of the rotational speed and outlet pressure on this rise was assessed. The results revealed using herringbone groove on the inner wall of bearing was effective in reducing the temperature increase. Therefore, the use of grooves represents a suitable method of reducing the temperature rise in the journal bearings of a high-speed gear pump.

An Analytical Iron Loss Calculation Model of Inverter-Fed Induction Motors Considering Supply and Slot Harmonics

A fast and accurate analytical inverter-fed induction machine iron loss calculation model is proposed in this paper. The proposed model takes account of the influence of the output voltage harmonics from the inverter on the iron loss of the motor based on the piecewise variable coefficients method. Additionally, the proposed method incorporates slot harmonic component's influence on the iron loss. The validity of the proposed model is verified by comparing its calculated core loss values with measured ones of a 5.5- and a 55-kW inverter-fed induction motors under different speeds and load conditions. Compared with the classical iron loss model and piecewise variable coefficient iron loss model based on the finite-element method, the proposed model can reduce the computational burden significantly with desirable accuracy.

Case study to determinate the angle-dependence during the risk determination in lightning protection

To know the formation of the atmospheric discharge is one of the main starting point to create an accurate calculation model. In this paper a study will be discussed what kind of modifications are necessary improve PMAS (probability-Modulated Attractive Space) [1, 2] calculation by taking into consideration the geometrical position of downward leader, especially the direction of the last step between the striking point and the point of strike.The PMAS is a widely used method to calculate the probability of lightning strike for an object. Based on this calculation it is possible to get the expected number of strikes for a given object in a certain time-period. In the standard method, EGM (Electro-Geometry Method) the correlation between the current and the striking distance are proportional. In the paper [3], for the current distance-dependence was made a weighted solution, but it has no angle-dependence, also. This one was calculated by the help of different EGM.The connection between the striking distance, lightning current and striking distance is not examined in the case of direction. In the work, the main question is this dependence, and the main goal is to define the context.

Accurate Density Calculation for Molten Slags in SiO2-Al2O3-CaO-MgO-‘FeO’-‘Fe2O3’ Systems

A simple and accurate density calculation model for molten slags containing iron oxides in SiO2-Al2O3-CaO-MgO-‘FeO’-‘Fe2O3’ systems is established in the present study, by extending a previous model developed for SiO2-Al2O3-CaO-MgO systems. To quantitate the iron oxides in slags, a new method is proposed to recalculate all the iron oxides as ‘FeO’ and ‘Fe2O3,’ which represent the iron oxides in equilibrium with metallic iron and the air atmosphere, respectively. This method is essentially different from most of the other models that dealt with ferrous (FeO) and ferric (Fe2O3) iron oxides. A total of 860 experimental data points for iron oxide-containing melts are critically collected for the optimization of the model parameters. The model achieves an excellent agreement with literature values with an average error of 1.96 pct and an overall absolute error of 0.092 g/cm3. The compositional dependences from unary to multicomponent systems are discussed using the present model. The results show that the densities always increase with the increasing ‘FeO’ or ‘Fe2O3,’ and the substitution of ‘FeO’ by ‘Fe2O3’ will cause a decrease in density. In the multicomponent systems, SiO2 tends to have a larger impact on the density of ‘Fe2O3’-containing systems compared with ‘FeO’-containing systems.

Dynamic conductivity of polymer dielectrics under time-varying temperature field

We succeeded in putting forward a two-dimensional electric transport model based on the first-order kinetic charge trapping/detrapping model. The dynamic conductivity under thermal cycle of polyimide is analyzed from numerical calculations and experimental tests. The conductivity characteristics of polymer dielectric under temperature cycling was found to be dominated by temperature and time, because of filled traps and rapid changes in temperature. The present study contributes in providing an accurate conductivity calculation model for polymer dielectrics under temperature-varying fields.

Stone masonry buildings: Analysis of structural acoustic and energy performance within the seismic safety criteria

Natural stone masonry is a building technology largely used all over the world, since the dawn of humankind. At present day stone masonry buildings, beyond being naturally characterized by intrinsic building physics performances, allow to reconsider the use of natural stone masonry (together with new technological supports, components and materials), as a promising “new trend” for both newly developed buildings and renovation of existing buildings, in particular where it is a priority to retrieve the historical identity of the urban landscape.In this paper, energy performance and structural-acoustic properties of stone masonry buildings, in compliance with seismic safety criteria, are investigated and discussed on the basis of current technical standards and scientific literature. Related performances are evaluated by means of accurate calculation models. The results show that stone masonry buildings can offer often higher performance than those normally attributed to it.

Nonlinear Creep Damage Constitutive Model of Concrete Based on Fractional Calculus Theory.

Concrete creep has become one of the major problems that threatens concrete structural development and construction. However, a reasonable and accurate calculation model for numerical analysis is the key to control and solve the creep deformation of concrete. To better describe the concrete nonlinear creep damage evolution rule, the visco-elasticity Plasticity Rheological Theory, Riemann Liouville Theory and Combined Model Theory are quoted, and the Able dashpot is used to reconstruct fractional-order soft-body composite elements to propose the expression of the stress-strain relationship of the elastomer, visco-elasticity plasticity body, and Viscoplasticity body, considering the evolution of the concrete compression damage process. A nonlinear creep damage constitutive model of concrete, based on fractional calculus theory, is conducted, and the parameters of the specific calculation method of the model are given. The influence of stress level σ, fractional order n and material parameter α on the concrete creep process is determined by a sensitivity analysis of the model parameters. The creep process and deformation amount of concrete in practical engineering can be effectively controlled by the results of the proposed sensitivity analysis. The research results can be used to provide guidance and reference for the safe construction of concrete engineering in actual practice.

Strain-optoelectronic coupling properties of externally deformed nanoribbons with embedded quantum well

Strain-engineering provides a critical mechanism for tuning the band structure of quantum wells (QWs). However, due to the inherent rigidity of the semiconductor materials, the strain induced by lattice-mismatch is restricted to be invariable, uniform, thus cannot be subject to direct mechanical loading processes. Therefore, the flexible nanoribbons (NRs) in a variety of configurations offer entirely new research perspectives in modulation of the optoelectronic characteristic of QWs by curvature-induced inhomogeneous strain. In this paper, we propose a strategy to fabricate the QW layer embedded in uniaxially wavy NRs. To thoroughly figure out the internal strain-optoelectronic coupling mechanism, we establish a simple and accurate calculation model for externally deformed QW NRs using the eight-band k·p perturbation method for the first time. Luttinger-Kohn-Pikus-Bir Hamiltonian (LKPBH) for strained semiconductor is adopted and solved by finite-difference method (FDM). Theoretical calculations reveal inclined band edges, which result in the quantum-confined stark effect (QCSE) in the bended QW NRs. Continuously and periodically varied band gap of the wavy QW is revealed with a blue-shift from peak to valley of the sample NR, which agrees well with the μ-photoluminescence measurements. Further adjustments of the external configuration are explored to study the impact of the larger deformed structure on the curvature and band gap of the wavy QW within the confinement of the fracture limit.

Research on Mechanics of Longitudinal Joint in Shield Tunnel by the Nonlinear Spring Equivalent Method

Shield tunnel lining is mainly composed of prefabricated segment, accurate description of longitudinal seam joint mechanics is important for design and analysis of shield tunnel segmental linings, however, due to its stress state is complex and internal force changes show the characteristics of nonlinear, there is no more rapid and accurate calculation model to analysis the mechanics. In the view of the problem of the entity unit simulating bolt bending with low computing speed, the model of shield tunnel longitudinal seam that using the nonlinear spring to simulate bending bolt joint is proposed. Combined with longitudinal seam joint test, analysis the entity model and spring bolt model, the study concluded that: 1) the calculation results of spring bolt model are closer to the test results than entity unit model; and 2) calculation efficiency of spring bolt model bolt up 1 times than the physical model. Based on the spring bolt model, further study the relationship between viscous coefficient, friction coefficient and calculation efficiency, and analyzes the regularity of deformation and damage of shield tunnel connection.

Core, Mode, and Spectrum Assignment Based on Machine Learning in Space Division Multiplexing Elastic Optical Networks

Recently, network traffic has been growing exponentially and almost reached the physical capacity limit of single mode fibers. Space division multiplexing (SDM) is a promising technology to overcome the looming fiber capacity crunch. Especially, few-mode multi-core fibers (FM-MCFs) can aggregate multiple cores into one fiber and two or more modes can be transmitted in one core, which can greatly increase the capacity yet introduce crosstalk constraints including inter- and intra-core crosstalk. To our best knowledge, there is no accurate crosstalk calculation model study in SDM optical networks with FM-MCFs. To address this issue, we first introduce the machine learning into the crosstalk prediction phase and propose a novel crosstalk estimation model (CEM) exploiting the beam propagation method called CEM-beam propagation method (BPM)-machine learning (ML), which can be used to evaluate the crosstalk during the design for the resource allocation scheme. Then, a crosstalk aware core, mode, and spectrum assignment (CA-CMSA) strategy is presented. The simulation results for crosstalk estimation at the wavelength level indicate that the crosstalk at lower frequencies is less than that at higher frequencies. Thus, the lower frequencies are always the first choice in the spectrum resource assignment phase. In addition, for our specific training set, the Levenberg-Marquardt (LM) algorithm based on machine learning performs better on the training, including regression values measurement and time consumption. The simulation results of the proposed CA-CMSA scheme also show that the resource allocation algorithm based on LM can improve resource utilization without increasing total connection set-up time. Thus, it will be the best choice for the resource assignment in SDM networks with FM-MCFs.

Monte Carlo Simulation for Radiative Transfer in a High-Pressure Industrial Gas Turbine Combustion Chamber

Radiative heat transfer is studied numerically for reacting swirling flow in an industrial gas turbine burner operating at a pressure of 15 bar. The reacting field characteristics are computed by Reynolds-averaged Navier–Stokes (RANS) equations using the k-ϵ model with the partially stirred reactor (PaSR) combustion model. The GRI-Mech 2.11 mechanism, which includes nitrogen chemistry, is used to demonstrate the ability of reducing NOx emissions of the combustion system. A photon Monte Carlo (PMC) method coupled with a line-by-line (LBL) spectral model is employed to accurately account for the radiation effects. Optically thin (OT) and PMC–gray models are also employed to show the differences between the simplest radiative calculation models and the most accurate radiative calculation model, i.e., PMC–LBL, for the gas turbine burner. It was found that radiation does not significantly alter the temperature level as well as CO2 and H2O concentrations. However, it has significant impacts on the NOx levels at downstream locations.

Cross-coupling control method for five-axis computer numerical control machine with dual rotary tables

The contour error cross-coupling control is very important to improve contour accuracy for the five-axis computer numerical control machine. The change in cutter orientation can cause the nonlinear motion of cutter tip, so the contour error calculation and compensation are very complex. For the five-axis computer numerical control machine with dual rotary tables, the forward kinematics model and inverse kinematics model are set up, and the influence laws of feed axis deviation to cutter tip deviation and cutter orientation deviation are studied. Then the simple and accurate calculation models for cutter tip contour error and cutter orientation contour error are established. Finally, the novel contour error cross-coupling control method based on kinematics model is developed. The experimental results show that the developed method can effectively improve contour accuracy of the five-axis computer numerical control machine.

Tool orientation optimization of 5-axis ball-end milling based on an accurate cutter/workpiece engagement model

Tool orientation in 5-axis ball-end milling plays a significant role in machining efficiency and accuracy. The cutter/workpiece engagement varies with tool orientation continuously including lead and tilt angles during machining, which results in the obvious time-varying characteristic for consecutive cutting forces. Considering tool orientation, actual cutter runout and cutter motion process, an accurate calculation model for instantaneous cutter/workpiece engaging process in 5-axis ball-end milling is proposed based on an improved analytical method with high order Taylor formula, which can reach an excellent accuracy. Then base on the cutting force model, the tool orientation optimization strategies with a flexible cutter and rigid workpiece for roughing and finishing milling operation are further presented. For the three kinds of geometrical characteristic (plane, cylindrical and spherical surface), this study analyzes the influence of tool lead and tilt angles, and step over on the maximum cutting force and form error, and finally obtains an optimal tool orientation to realize a high efficiency and accuracy machining.

Impact of dose calculation models on radiotherapy outcomes and quality adjusted life years for lung cancer treatment: do we need to measure radiotherapy outcomes to tune the radiobiological parameters of a normal tissue complication probability model?

The equivalent uniform dose (EUD) radiobiological model can be applied for lung cancer treatment plans to estimate the tumor control probability (TCP) and the normal tissue complication probability (NTCP) using different dose calculation models. Then, based on the different calculated doses, the quality adjusted life years (QALY) score can be assessed versus the uncomplicated tumor control probability (UTCP) concept in order to predict the overall outcome of the different treatment plans. Nine lung cancer cases were included in this study. For the each patient, two treatments plans were generated. The doses were calculated respectively from pencil beam model, as pencil beam convolution (PBC) turning on 1D density correction with Modified Batho's (MB) method, and point kernel model as anisotropic analytical algorithm (AAA) using exactly the same prescribed dose, normalized to 100% at isocentre point inside the target and beam arrangements. The radiotherapy outcomes and QALY were compared. The bootstrap method was used to improve the 95% confidence intervals (95% CI) estimation. Wilcoxon paired test was used to calculate P value. Compared to AAA considered as more realistic, the PBCMB overestimated the TCP while underestimating NTCP, P<0.05. Thus the UTCP and the QALY score were also overestimated. To correlate measured QALY's obtained from the follow-up of the patients with calculated QALY from DVH metrics, the more accurate dose calculation models should be first integrated in clinical use. Second, clinically measured outcomes are necessary to tune the parameters of the NTCP model used to link the treatment outcome with the QALY. Only after these two steps, the comparison and the ranking of different radiotherapy plans would be possible, avoiding over/under estimation of QALY and any other clinic-biological estimates.

Structural Design and Analysis of Aluminum Dome for Caofeidian Coal Storage

The upper part of Caofeidian coal storage was approximately hemispherical aluminum shell, covered with aluminum alloys plate. The capsule was made of aluminum alloys material, and its span was 125 meters. In the design, according to TEMCOR joint, we used the finite element software MIDAS to build the accurate geometry models and calculation models of aluminum alloys single layer latticed dome structures. By the combination of constant loads, live loads, snow load, wind load, temperature effect and other working conditions, we summarized the consumption of aluminum of the structures, and studied the structural internal force, structural deformation and structural stiffness. In addition, the X and Y two different direction seismic dynamic load was applied to the structure. The structural seismic performance under two kinds of modes were studied through the structure mode analysis of the vibration frequency. The vierendeel dome and single layer dome were controlled by the stability. ANSYS three-dimensional frame element model were set up, and the eigenvalue buckling analysis was carried out. By the geometrical nonlinear finite element method, combining with initial imperfections and material nonlinear, we found out the stability coefficient and the weak parts of the structure.

Analysis of CFSE time-series data using division-, age- and label-structured population models.

In vitro and in vivo cell proliferation is often studied using the dye carboxyfluorescein succinimidyl ester (CFSE). The CFSE time-series data provide information about the proliferation history of populations of cells. While the experimental procedures are well established and widely used, the analysis of CFSE time-series data is still challenging. Many available analysis tools do not account for cell age and employ optimization methods that are inefficient (or even unreliable). We present a new model-based analysis method for CFSE time-series data. This method uses a flexible description of proliferating cell populations, namely, a division-, age- and label-structured population model. Efficient maximum likelihood and Bayesian estimation algorithms are introduced to infer the model parameters and their uncertainties. These methods exploit the forward sensitivity equations of the underlying partial differential equation model for efficient and accurate gradient calculation, thereby improving computational efficiency and reliability compared with alternative approaches and accelerating uncertainty analysis. The performance of the method is assessed by studying a dataset for immune cell proliferation. This revealed the importance of different factors on the proliferation rates of individual cells. Among others, the predominate effect of cell age on the division rate is found, which was not revealed by available computational methods. The MATLAB source code implementing the models and algorithms is available from http://janhasenauer.github.io/ShAPE-DALSP/Contact: jan.hasenauer@helmholtz-muenchen.de Supplementary data are available at Bioinformatics online.

An Accurate Calculation Model of Carbon Emissions in Coal Fired Power Plant

An Accurate Calculation Model of Carbon Emissions in Coal Fired Power Plant

TU-EF-BRD-03: Mental Workload and Performance

Research related to quality and safety has been a staple of medical physics academic activities for a long time. From very early on, medical physicists have developed new radiation measurement equipment and analysis techniques, created ever increasingly accurate dose calculation models, and have vastly improved imaging, planning, and delivery techniques. These and other areas of interest have improved the quality and safety of radiotherapy for our patients. With the advent of TG-100, quality and safety is an area that will garner even more research interest in the future. As medical physicists pursue quality and safety research in greater numbers, it is worthwhile to consider what actually constitutes research on quality and safety. For example, should the development of algorithms for real-time EPID-based in-vivo dosimetry be defined as “quality and safety” research? How about the clinical implementation of such as system? Surely the application of failure modes and effects analysis to a clinical process would be considered quality and safety research, but is this type of research that should be included in the medical physics peer-reviewed literature? The answers to such questions are of critical importance to set researchers in a direction that will provide the greatest benefit to our field and the patients we serve. The purpose of this symposium is to consider what constitutes research in the arena of quality and safety and differentiate it from other research directions. The key distinction here is developing the tool itself (e.g. algorithms for EPID dosimetry) vs. studying the impact of the tool with some quantitative metric. Only the latter would I call quality and safety research. Issues of ‘basic’ versus ‘applied’ quality and safety research will be covered as well as how the research results should be structured to provide increasing levels of support that a quality and safety intervention is effective and sustainable. Examples from existing peer-reviewed research will be used to highlight the main points. Historical, medical physicists have leveraged many areas of applied physics, engineering and biology to improve radiotherapy. Research on quality and safety is another area where physicists can have an impact. The key to further progress is to clearly define what constitutes quality and safety research for those interested in doing such research and the reviewers of that research. Learning Objectives: 1. List several tools of quality and safety with references to peer-reviewed literature. 2. Describe effects of mental workload on performance. 3. Outline research in quality and safety indicators and technique analysis. 4. Understand what quality and safety research needs to be going forward. 5. Understand the links between cooperative group trials and quality and safety research.

TU-EF-BRD-00: The Science of QA

Research related to quality and safety has been a staple of medical physics academic activities for a long time. From very early on, medical physicists have developed new radiation measurement equipment and analysis techniques, created ever increasingly accurate dose calculation models, and have vastly improved imaging, planning, and delivery techniques. These and other areas of interest have improved the quality and safety of radiotherapy for our patients. With the advent of TG-100, quality and safety is an area that will garner even more research interest in the future. As medical physicists pursue quality and safety research in greater numbers, it is worthwhile to consider what actually constitutes research on quality and safety. For example, should the development of algorithms for real-time EPID-based in-vivo dosimetry be defined as “quality and safety” research? How about the clinical implementation of such as system? Surely the application of failure modes and effects analysis to a clinical process would be considered quality and safety research, but is this type of research that should be included in the medical physics peer-reviewed literature? The answers to such questions are of critical importance to set researchers in a direction that will provide the greatest benefit to our field and the patients we serve. The purpose of this symposium is to consider what constitutes research in the arena of quality and safety and differentiate it from other research directions. The key distinction here is developing the tool itself (e.g. algorithms for EPID dosimetry) vs. studying the impact of the tool with some quantitative metric. Only the latter would I call quality and safety research. Issues of ‘basic’ versus ‘applied’ quality and safety research will be covered as well as how the research results should be structured to provide increasing levels of support that a quality and safety intervention is effective and sustainable. Examples from existing peer-reviewed research will be used to highlight the main points. Historical, medical physicists have leveraged many areas of applied physics, engineering and biology to improve radiotherapy. Research on quality and safety is another area where physicists can have an impact. The key to further progress is to clearly define what constitutes quality and safety research for those interested in doing such research and the reviewers of that research. Learning Objectives: 1. List several tools of quality and safety with references to peer-reviewed literature. 2. Describe effects of mental workload on performance. 3. Outline research in quality and safety indicators and technique analysis. 4. Understand what quality and safety research needs to be going forward. 5. Understand the links between cooperative group trials and quality and safety research.