Simultaneous Solution Research Articles

Numerical research on adverse effect of muzzle flow formed by muzzle brake considering secondary combustion

The simulation of the artillery interior and intermediate ballistics problem is performed to investigate the influence of a gas dynamics device, muzzle brake, on the muzzle hazard phenomena, such as flash and blast waves. The correlation of the chemical reactions with the characteristics of the muzzle flow field is analyzed by the simulation for a further understanding of the secondary combustion phenomenon of the muzzle flow. The novel structure of muzzle flow caused by the muzzle brake is presented by the simultaneous solution of the interior ballistics model and multi-species Navier-Stokes equations in order to analyze the influence of the muzzle brake structure on the chemical reactions. The secondary combustion of the muzzle flow due to the oxygen-supplement chemical reactions is obtained by the chemical reaction kinetic model. The interaction of the blast waves released from the muzzle brake is illustrated in detail and the mechanism of the formation of muzzle flash is analyzed. This research provides a reference for the studies on the suppression of the muzzle flash.

Rapid energy flow calculation method for integrated electrical and thermal systems

The specific solution methodologies adopted for solving multi-energy flow problems involving integrated energy systems (IESs), such as integrated electrical and thermal energy systems, suffer from a number of deficiencies, such as the choice of iterative initial values when using Newton–Raphson method, poor numerical stability and computational efficiency issues. While the computational complexity of the district heating system model increases dramatically as the scale of the system increases. As such, the development of a new solution algorithm suitable for application to the complex models of large IESs is urgently required. Therefore, this paper proposes a rapid multi-energy flow calculation method for integrated electrical and thermal energy systems. Firstly, an equivalent function of the pipeline pressure drop equation is derived to avoid the iterative and simultaneous solution of crucial pipeline parameters. Secondly, a linear equation is introduced to decouple and transform a typical ring district heating system into a collection of radial district heating systems, which can be rapidly solved with high-precision. Numerical applications of the proposed approach to the Barry Island system verify that the approach provides accurate and highly efficient multi-energy flow calculations.

The Cauchy Integral Formula in Hermitian, Quaternionic and $$\mathfrak {osp}(4|2)$$ Clifford Analysis

As is the case for the theory of holomorphic functions in the complex plane, the Cauchy Integral Formula has proven to be a cornerstone of Clifford analysis, the monogenic function theory in higher dimensional euclidean space. In recent years, several new branches of Clifford analysis have emerged. Similarly as to how hermitian Clifford analysis in euclidean space $${\mathbb {R}}^{2n}$$ of even dimension emerged as a refinement of euclidean Clifford analysis by introducing a complex structure on $${\mathbb {R}}^{2n}$$ , quaternionic Clifford analysis arose as a further refinement by introducing a so-called hypercomplex structure $${\mathbb {Q}}$$ , i.e. three complex structures ( $${\mathbb {I}}$$ , $${\mathbb {J}}$$ , $${\mathbb {K}}$$ ) which follow the quaternionic multiplication rules, on $${\mathbb {R}}^{4p}$$ , the dimension now being a fourfold. Two, respectively four, differential operators lead to first order systems invariant under the action of the respective symmetry groups U(n) and Sp(p). Their simultaneous null solutions are called hermitian monogenic and quaternionic monogenic functions respectively. In this contribution we further elaborate on the Cauchy Integral Formula for hermitian and quaternionic monogenic functions. Moreover we establish Caychy integral formulae for $$\mathfrak {osp}(4|2)$$ -monogenic functions, the newest branch of Clifford analysis refining quaternionic monogenicity by taking the underlying symplectic symmetry fully into account.

Thermohydrodynamic (THD) Analysis of Journal Bearing Operating with Bio-based Nanolubricants

The objective of current research is to study the adiabatic solutions of a plain journal bearing operating with bio-based lubricants containing nanoparticles. Estimation of pressure and temperature fields has been accomplished by simultaneous numerical solutions of the modified Reynolds equation and the adiabatic energy equation. These equations have been solved by adopting the finite difference method with suitable iterative scheme. The analysis has been carried out taking into account the heating effects and non-Newtonian rheology of bio-based nanolubricant following the power law model. The results have been investigated for temperature and pressure fields and the static performance parameters for a broad range of eccentricity ratio e and different power law index values. The calculated results present that the involvement of nanoparticles in bio-based lubricant significantly enhances the pressure, load carrying capacity and friction force. Moreover, the influence of thermal effects on performance parameters is seen to be maximum at higher values of power law index.

3D MHD nonlinear radiative flow of CuO-MgO/methanol hybrid nanofluid beyond an irregular dimension surface with slip effect

The 3D MHD nonlinear radiative hybrid nanofluid flow across an irregular dimension sheet with slip effect is studied numerically. The hybrid nanofluid consists of copper oxide (CuO) and magnesium oxide (MgO) nanoparticles embedded in methanol or methyl alcohol (MA). The governing PDEs’ are altered as ODEs’ using similarities and numerical solutions are attained using shooting scheme. The role of corporal factors on the transport phenomenon is analyzed and reflected by plots and numerical interpretations. Simultaneous solutions presented for CuO-MA nanofluid and CuO-MgO/MA hybrid nanofluid. Results ascertain that the temperature and flow boundary layer thicknesses are not unique for the hybrid nanofluid and nanofluid. The heat transfer enactment of CuO-MA nanofluid is high when equated to CuO-MgO/MA hybrid nanofluid. This concludes that the CuO-MgO combination works as a good insulator.

Trajectory Drift–Compensated Solution of a Stereo RGB-D Mapping System

Multiple sensors are commonly used for three-dimensional (3D)-mapping or robotic-vision applications, as they provide a larger field of view and sufficient observations to fulfill frame-registration and map-updating tasks. However, the data sequences generated by multiple sensors can be inconsistent and contain significant time drift. In this paper, we describe the trajectory drift–compensated strategy that we designed to eliminate the influence of time drift between sensors, remove the inconsistency between the sequences from various sensors, and thereby generate a coarse-to-fine procedure for robust camera-tracking based on two-dimensional–3D observations from stereo sensors. We present the mathematical analysis of the iterative optimizations for pose tracking in a stereo red, green, blue plus depth (RGB-D) camera. Finally, complex indoor scenario experiments demonstrate the efficiency of the proposed stereo RGB-D simultaneous localization and mapping solution. The results verify that the proposed stereo RGB-D mapping solution effectively improves the accuracies of both camera-tracking and 3D reconstruction.

Mixed elastohydrodynamic lubrication analysis of line contact with Non-Gaussian surface roughness

An approach for mixed elastohydrodynamic lubrication (EHL) analysis of line contact with non-Gaussian rough surface is proposed, and a minimum film thickness formula is derived based on the simultaneous solutions. The Patir and Cheng's average flow model and Kogut and Etsion's rough surface contact model is used to obtain hydrodynamic pressure and asperity pressure. The effect of non-Gaussian rough surface on pressure, film thickness and asperity-to-total load ratio are studied. It is observed that the influence of kurtosis on pressure and film thickness is slight. Both skewness and kurtosis have strong effect on asperity-to-total load ratio. Lastly, a minimum film thickness is derived and expresses as a function of dimensionless load, speed, material, standard deviation and skewness.

Impact of linear/nonlinear radiation on incessantly moving thin needle in MHD quiescent Al-Cu/methanol hybrid nanofluid

ABSTRACT The present work describes the periphery layer exploration of a magnetohydrodynamic hybrid nanofluid (Al-Cu/methanol) flow besides an unceasingly moving needle submerged horizontally in the flow field. The presumption is that the thermal radiation is linear/nonlinear. The border layer conduct is inspected under the purview of Sakiadis (quiescent fluid) situation. The central system of partial differential equations’ is transmuted as a system of ordinary differential equations' and unravelled by engaging the R-K method established shooting technique. Numerical deduction of thermal transport, wall friction is tabulated and accordingly interpreted. The designations of velocity and thermal fields are examined by graphical illustrations. Simultaneous solutions attained to reveal the superior nature of aluminium-copper/methanol hybrid nanofluid compared to methanol-based Al-Cu alloy nanofluid (with 50% aluminium and 50% copper). An elevation in needle thickness has an increased implication on the heat transfer rate of hybrid nanoliquid. Also, nonlinear thermal radiation has remarkable influence on thermal profiles than linear.

On the role of acoustic reflections from duct boundaries in fan flutter

The role that acoustic reflections from duct boundaries play in aeroengine fan flutter is theoretically investigated. To make a systematic parametric study attainable, a three-dimensional semi-analytical approach is employed. Based on the transfer element method combined with a boundary integral equation method, this approach effectively captures the acoustic coupling effect of an annular rotor undergoing incipient oscillation and a finite-length non-rigid duct in subsonic flow. For a given vibration mode, the disturbances generated both inside and outside the duct are determined by a simultaneous solution. The flutter likelihood is subsequently evaluated through the energy method. Results reveal that near the flutter boundary, the aeroelastic impact of duct boundary reflections becomes evident and critical when propagating (cut-on or weakly damped) acoustic modes exist in the flow duct. Under such condition the aerodynamic interaction between both duct openings strongly affects the sound field distribution, thus contributing to the notable installation effect on aeroelastic stability. Moreover, the flutter-driven acoustic field is also susceptible to the sound reflection effect of the partially lined duct wall. It is found that the variation of the blade aerodynamic damping with the liner impedance is markedly different when the duct end reflections come into play. Under appropriate conditions the mutual effect of the lined wall and the duct openings significantly strengthens their acoustic couplings with the ducted fan, where a reasonable estimate of aeroelastic stability can only be provided with an adequate consideration of the realistic acoustic boundary conditions for the entire duct.

Numerical Investigation of the Instability-Based Power Emission from an Ungated Plasmonic HEMT Using Complete Hydrodynamic Model

The full-wave analysis of the Dyakonov–Shur instability in an ungated short-channel high electron mobility transistor (HEMT) is investigated in this paper. This mechanism causes the emission of electromagnetic radiations by the device. The accurate analysis of the device is important especially when large electric fields are present. Herein, to analyze such structures, the complete hydrodynamic model, which is the simultaneous solution of Maxwell’s equations and the first three moments of the Boltzmann transport equation, is used. This model well describes the electron-wave interactions by considering the transport parameter variations with the electron energy and temperature. These variations are especially considerable when the emitter operates at high electromagnetic fields and were not considered in previous studies. The obtained results demonstrate the oscillation current along the channel and consequently the radiated power of the device are severely influenced by the transport parameter variations. The developed analysis method describes the behavior of the device as a terahertz emitter more accurately than the available ones.

Viscoelastic Finite Line Contact of Thin Bonded Layered Solids of Low Elastic Modulus

A new finite element-based contact mechanics analysis of layered viscoelastic solids of low elastic modulus is presented. The methodology is based on the Maxwell viscoelastic element, with stress relaxation taken into account by the Prony series’ representation of the bulk and shear material moduli. Simultaneous solutions for deviatoric and volumetric stresses were obtained under instantaneous elastic and subsequent viscoelastic relaxation, at multiples of the relaxation time of a Highly Filled Carbon Polymer (HFCP) layer. The results of the analysis were validated by a constructed, multi-layered sandwich sensor comprising the HFCP sensing elements covered by a protective silicone rubber surface of very low elastic modulus. The combined numerical-experimental approach, and the validated viscoelastic layered contact mechanics represent the original contribution of this paper, not hitherto reported in literature.

QMPI: A next generation MPI profiling interface for modern HPC platforms

As modern HPC applications and systems advance to exascale, their complexity and the need for more efficient resource utilization increases. This fact demands more advanced monitoring, analysis and optimization approaches. Therefore, the Message Passing Interface (MPI), which is the most common parallel programming system for HPC applications, must enable these advanced approaches. Even if the existing MPI Profiling Interface, PMPI, provides comprehensive tool support, it is no longer sufficient to enable these advanced approaches. In particular, PMPI does not support simultaneous or collaborative monitoring solutions from multiple different agents or sources. In this paper we introduce our interface QMPI, which addresses these limitations of PMPI and aims to be a successor to it. This paper presents the use cases and requirements that necessitate the development of QMPI, as well as a design offer for a QMPI prototype followed by its implementation and evaluation.

Experimental Investigations of the Fe-Mn-Ti System in the Concentration Range of up to 30\xa0at.% Ti

The ternary Fe-Mn-Ti system was investigated in the compositional range of up to 30 at.% Ti for temperatures ranging from 1000 °C to the melting temperature. Based on the metallographic investigation of as-cast alloys a partial liquidus projection was constructed, revealing large primary solidifying regions for the phases A1, A2, A12, A13, C14 and Mn4Ti. Isothermal heat treatments at 1000 and 1200 °C revealed wide homogeneity ranges for the Mn-based phases A12 and A13 at Ti contents between 5 and 20 at.% and up to 65 at.% of Fe, indicating an electron-mediated stabilization of both phases for the simultaneous solution of Fe and Ti.

Effect of radiation on engine oil-TC4/NiCr mixture nanofluid flow over a revolving cone in mutable permeable medium

Abstract In this study, we premeditated the free convective flow of time-independent hybrid nanofluid flow above a rotating upright cone in the mutable permeable medium. The heat transmission is deliberated in the attendance of nonlinear radiative heat flux. We considered the TC4 (Ti-6Al-4 V) and Nichrome (80%Ni and 20%Cr) nanoparticles and suspended them into unused Engine Oil (EO). Simultaneous solutions are presented for unused engine oil and hybrid nanofluid cases. Runge-Kutta and Newton’s methods resolve the transferred governing system. The influence of numerous emerging limits on velocity and temperature is examined graphically. Also, wall resistance and Nusselt number are discussed numerically. It is originated that the thermal field of EO-TC4/NiCr hybrid nanofluid is highly influenced by the inverse Darcy number, thermal radiation, and cone angle parameters. The heat transmission rate of EO-TC4/NiCr hybrid nanoliquid is comparatively lower than the base liquid (engine oil).

Appearance and Action: The Sequential Organization of Instructions in Japanese Calligraphy Lessons

ABSTRACT Drawing on an analysis of Japanese calligraphy (shodô) lessons where a master reviews his students’ works, I explore the organization of sequences in which the master proposes the correction or improvement of how they draw Japanese or Chinese characters. In such cases, the master faces two organizational issues: (a) how to organize his seeing of a drawn character in an adequately convincing manner, under the aspect of the drawing action that caused its appearance; and (b) how to organize the instruction sequences in a pedagogically adequate manner, by beginning with an explicit indication of the problem regarding the appearance of the character. I argue that the eventually accomplished sequences are the result of the simultaneous solution of these two issues. In conclusion, I reflect on some implications for further investigations of multimodal perception in distinct activities. Data are in Japanese with English translations.

Effect of asymmetrical heat rise/fall on the film flow of magnetohydrodynamic hybrid ferrofluid

The movement of the ferrous nanoparticles is random in the base fluid, and it will be homogeneous under the enforced magnetic field. This phenomenon shows a significant impact on the energy transmission process. In view of this, we inspected the stream and energy transport in magnetohydrodynamic dissipative ferro and hybrid ferrofluids by considering an uneven heat rise/fall and radiation effects. We studied the Fe3O4 (magnetic oxide) and CoFe2O4 (cobalt iron oxide) ferrous particles embedded in H2O-EG (ethylene glycol) (50–50%) mixture. The flow model is converted as ODEs with suitable similarities and resolved them using the 4th order Runge-Kutta scheme. The influence of related constraints on transport phenomena examined through graphical illustrations. Simultaneous solutions explored for both ferro and hybrid ferrofluid cases. It is found that the magnetic oxide and cobalt iron oxide suspended in H2O-EG (ethylene glycol) (50–50%) mixture effectively reduces the heat transfer rate under specific conditions.

An equation-oriented novel approach for modeling the falling film absorber using rigorous thermodynamic and transport description

Falling liquid films are largely employed in heat and mass transfer processes in a variety of industrial systems, including absorption processes using NH3 and H2O as working fluid. This study develops a new approach based on differential algebraic model for the absorption of NH3 from a gaseous stream by a solution of NH3 and H2O in a falling film absorber at steady-state. Unlike the usual approach in literature, wherein sequential algorithms are specifically tailored to solve the model, the full set of differential algebraic equations (DAE) has been formulated and solved in an equation-oriented fashion. A rigorous modeling of the vapor–liquid equilibrium at the interface is proposed and compared with the usually employed empirical correlations. Thermal and transport properties (TTP) are computed by CAPE-OPEN interfaces, providing robustness and flexibility to the model. The TTP and the falling film model are validated with experimental data from literature. The results indicate that the liquid falling film imposes the dominant mass transfer resistance compared to the gas phase, whereas the coolant-side imposes the dominant heat transfer resistance. The simultaneous solution of the DAE system is very efficient, robust and flexible, as it can be applied for absorbers with different geometries and working fluids.

Many‐body response of benzene at monolayer MoS2: Van der Waals interactions and spectral broadening

AbstractModels of surface enhancement of molecular electronic response properties are challenging for two reasons: (a) molecule‐surface interactions require a simultaneous solution of the molecular and the surface dynamic response (a daunting task), and (b) when solving for the electronic structure of the combined molecule + surface system, it is not trivial to single out the particular physical effects responsible for enhancement. To tackle this problem, in this work, we apply a formally exact decomposition of the system's response function into subsystem contributions by using subsystem density functional theory (DFT), which grants access to dynamic polarizabilities and optical spectra. In order to access information about the interactions between the subsystems, we extend a previously developed subsystem‐based adiabatic connection fluctuation‐dissipation theorem of DFT to separate the additive from the nonadditive correlation energy and identify the nonadditive correlation as the van der Waals interactions. As an example, we choose benzene adsorbed on monolayer MoS2. We isolate the contributions to benzene's dynamic response arising from the interaction with the surface, and for the first time, we evaluate the enhancements to the effectiveness of C6 coefficients as a function of benzene‐MoS2 distance and adsorption site. We also quantify the spectral broadening of the benzene's electronic excited states due to their interaction with the surface. We find that the broadening has a similar decay law with the molecule‐surface distance as the leading van der Waals interactions (ie, R−6) and that the surface enhancement of dispersion interactions between benzene molecules is less than 5% but is still large enough (0.5 kcal/mol) to likely play a role in the prediction of interface morphologies.

The Improvement of the Mathematical Model of the Work Process of Borehole Ejection Systems

The article presents the sequence of deriving the equations which characterize the hydraulic system of jet pumps that carry out suction and injection-suction bottom flushing while drilling the production wells. The nature of flow distribution in the borehole ejection systems of the suction and injection-suction types is analyzed. The analysis is carried out taking into consideration the peculiarities of the calculation of branched hydraulic systems. While studying the movement of the flows in the bottom circulation circuits, the authors take into account the equation of the balance of the flow-rate at nodal points and hydraulic losses in parallel parts of the system. The developed mathematical models are based on the study of the changes in hydrodynamic pressures which occur in characteristic sections of a jet pump. The pressure ratio of mixed, injected and operating flows is presented as non-dimensional relative pressure of the ejection system. The dependence of non-dimensional relative pressure on the relative flow rate determines the characteristic of the hydraulic system of a jet pump. The relative flow rate or injection ratio of a jet pump is defined as the ratio of flow rate to injected and work flow. While analyzing the developed mathematical models, the authors specify the relation between the design and operating parameters of a jet pump. These parameters ensure its operation with maximum efficiency. Based on the study of the influence of the correlation between the diameters of the jet pump nozzles and the flushing system of the bit, the authors specify parameters which are optimal in terms of energy performance. The article provides the example of graphical determination of the operating point of a pumping unit. This determination is based on a simultaneous solution of the equations of the characteristics of the jet pump and the hydraulic system in which it operates. The improved techniques allow to predict the mode parameters of ejection systems and to determine the size of flowing part of the jet pump. They provide maximum energy performance of its workflow.

A fully coupled elastohydrodynamic model for static performance analysis of gas foil bearings

Gas foil bearings are increasingly employed in advanced rotating machinery. Fast and accurate predictions of bearing performance are necessary and can greatly improve the design of gas foil bearings. This paper presents a novel fully coupled elastohydrodynamic model for the static performance analysis of gas foil bearings. The novelty is the presentation of a simultaneous solution of a coupled elastohydrodynamic model that considers the detailed configuration, complex contact/separation and friction behaviors of the foil structure. The coupled model is established within a standard finite element framework, so it is easy to implement. The top and bump foils are modeled in detail with 2D beam elements, and a general contact model that includes separation and friction behaviors is used to model the interactions of the top and bump foils. The simultaneous solution of the system equation using the Newton–Raphson method is presented. An analytical Jacobian matrix of the system equation is given to guarantee and improve the convergence performance. The validity of the proposed model was proved by comparisons with analytical and experimental results. The numerical examples show that the proposed model that allows the separation of the top and bump foils accords better with engineering facts. The implementation of the Gümbel condition is discussed by comparing the results calculated by different models.