Novel methodology for turbine gas meters error curve modelling across a wide range of operating parameters

In this paper, performance of turbine flowmeters was investigated for different flowmeter ranges and working gas operating pressures. Variation of these parameters was represented in dimensionless form as a function of Reynolds Number and gas density ratio, while the relative flow measurement error was selected as the most important operating characteristic. A novel error curve model based on turbine machine theory and dimensionless analysis was introduced for the purpose of error data fitting across a wide range of gas flow rates and operating pressures. The main advantage of the presented model is the capability of accurate error data fitting with a single continuous equation, as demonstrated by high R 2 {R^{2}} values for the vast majority of flowmeters analyzed in this study. The acceptability criterion was designed based on the fact that the expanded measurement uncertainty of the relative error must not exceed 0.5 %. Besides an accurate interpolation, our model can also be utilized for prediction of turbine flowmeter performance at modified flow conditions (pressure and flow rate, working gas properties), and for assessment of the drift of flowmeter performance over time. The novel error curve model is demonstrated to outperform the standard polynomial-based model regardless of the independent variable used.

Existence of a solution of discrete Emden-Fowler equation caused by continuous equation

<p style='text-indent:20px;'>The paper studies the asymptotic behaviour of solutions to a second-order non-linear discrete equation of Emden–Fowler type</p><p style='text-indent:20px;'><disp-formula> <label/> <tex-math id="FE1"> \begin{document}$ \Delta^2 u(k) \pm k^\alpha u^m(k) = 0 $\end{document} </tex-math></disp-formula></p><p style='text-indent:20px;'>where <inline-formula><tex-math id="M1">\begin{document}$ u\colon \{k_0, k_0+1, \dots\}\to \mathbb{R} $\end{document}</tex-math></inline-formula> is an unknown solution, <inline-formula><tex-math id="M2">\begin{document}$ \Delta^2 u(k) $\end{document}</tex-math></inline-formula> is its second-order forward difference, <inline-formula><tex-math id="M3">\begin{document}$ k_0 $\end{document}</tex-math></inline-formula> is a fixed integer and <inline-formula><tex-math id="M4">\begin{document}$ \alpha $\end{document}</tex-math></inline-formula>, <inline-formula><tex-math id="M5">\begin{document}$ m $\end{document}</tex-math></inline-formula> are real numbers, <inline-formula><tex-math id="M6">\begin{document}$ m\not = 0, 1 $\end{document}</tex-math></inline-formula>.</p>

Dynamic secondary electron emission in rough composite materials

The interaction of ionizing radiation with matter is of critical importance in numerous areas of science and technology like space and vacuum technology and even medicine and biotechnology. Secondary electron emission is a consequence of electron irradiation on materials. We achieve extremely low secondary electron emission yield values smaller than 0.2, even up to incident electron energies ~1 keV, due to an undocumented synergy between neighbouring metal and dielectric domains in composite samples. To investigate this experimental discovery, we propose a simple 3D model where the dielectric and metallic domains are arranged in parallel and interleaved. The proposed surface profile has a triangular shape to model the surface roughness. We obtain a continuous equation to describe the electric field that arises between grounded conductors and charged dielectrics domains. The calculated trajectories of secondary electrons in this 3D geometry are used to predict dynamic secondary emission yield, which strongly depends on the charge accumulated in the dielectric domains. This research paves the way to design new materials of low secondary emission yield, addressing the technological problem not yet resolved to inhibit the electron avalanche in RF equipment that limit their maximum working power.

Effect of welding current on arc behavior in tandem GMAW

A three-dimensional numerical model of double-arc in tandem gas metal arc welding (GMAW) was established based on the theory of arc physics, momentum equation, energy equation, continuous equation and Maxwell equations. The effects of different welding current on temperature field, velocity field and pressure field on the surface of workpieces were investigated. The results showed that the maximum values of arc temperature, arc plasma velocity and arc pressure on workpieces surface were increased with the increasing welding current. These maximum values occurred at the tip of double-wire. The current density and axial deflection angle of coupling arc were increased following the increasing welding current.

A Discrete Negative Order Potential Korteweg–de Vries Equation

We investigate a discrete negative order potential Korteweg–de Vries (npKdV) equation via the generalised Cauchy matrix approach. Solutions more than multisoliton solutions of this equation are derived by solving the determining equation set. We also show the semidiscrete equation and continuous equation together with their exact solutions by considering the continuum limits.

Numerical Simulation on Air Flow Field of Tangential Longitudinal Axial Combine Harvester

Withthe use and popularization of the tangential longitudinal axial combineharvester,the cleaning device of high loss rate and impurity rate continuouslyemerging.In order to analyses the reason of cleaning performance is low,thestudy for airflow field distribution of thetangential-longitudinal axial combine harvester has been carried out.Based onhomogenization when Reynold continuous equation and navier-stokes equation andthe renormalization group (RNG) kappa epsilon turbulence model predominateconstitute a closed equations,Using CFD simulation software simulated thecleaning shoe airway airflow.The simulation results show that the cleaning shoeair distribution is symmetrical in the screen surface width direction.Along thescreen surface height direction airflow velocity decreases gradually,Along thescreen length direction ,at the front of the sieve air velocity is low,Near themiddle of the screen as to achieve the maximum of air velocity.And for cleaningshoe air flow field were measured experiment, verify the accuracy of flow fieldsimulation.

Finite volume schemes for diffusion equations: Introduction to and review of modern methods

We present Finite Volume methods for diffusion equations on generic meshes, that received important coverage in the last decade or so. After introducing the main ideas and construction principles of the methods, we review some literature results, focusing on two important properties of schemes (discrete versions of well-known properties of the continuous equation): coercivity and minimum–maximum principles. Coercivity ensures the stability of the method as well as its convergence under assumptions compatible with real-world applications, whereas minimum–maximum principles are crucial in case of strong anisotropy to obtain physically meaningful approximate solutions.

Simulation for Supporting Scale-Up of a Fluidized Bed Reactor for Advanced Water Oxidation

Simulation of fluidized bed reactor (FBR) was accomplished for treating wastewater using Fenton reaction, which is an advanced oxidation process (AOP). The simulation was performed to determine characteristics of FBR performance, concentration profile of the contaminants, and various prominent hydrodynamic properties (e.g., Reynolds number, velocity, and pressure) in the reactor. Simulation was implemented for 2.8 L working volume using hydrodynamic correlations, continuous equation, and simplified kinetic information for phenols degradation as a model. The simulation shows that, by using Fe3+and Fe2+mixtures as catalyst, TOC degradation up to 45% was achieved for contaminant range of 40–90 mg/L within 60 min. The concentration profiles and hydrodynamic characteristics were also generated. A subsequent scale-up study was also conducted using similitude method. The analysis shows that up to 10 L working volume, the models developed are applicable. The study proves that, using appropriate modeling and simulation, data can be predicted for designing and operating FBR for wastewater treatment.