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In the early research process, the ideal gas was taken as the research object, but in practice, the working fluid was all non-ideal gas, so it is of great significance to study performance of actual internal combustion engine with non-ideal gas. This study utilizes an irreversible Diesel cycle model, which has been established in the previous literature, and considers various irreversible loss terms and specific heat model of non-ideal gas working fluid, to perform cycle performance analysis and multi-objective optimization. Compression ratio ( γ ) is taken as optimization variable to optimize efficiency ( η ), dimensionless power ( P ¯ ), dimensionless power density ( P d ¯ ) and dimensionless ecological function ( E ¯ ). The results show that there are optimal γ s to maximize the four-objective functions ( η max , P ¯ max , P d ¯ max and E ¯ max ); with the rises of irreversible loss terms, the η max , P ¯ max , P d ¯ max and E ¯ max all drop. As freedom degree of monatomic gas changes from 1 to 3, only η max drops and the other three-objective functions rise. When P ¯ - η - E ¯ - P ¯ d is optimized and γ opt is mainly concentrated between 3.6 and 5.3, the calculation results of P ¯ are distributed between 0.85 and 1. The calculation results of η are distributed between 0.46 and 0.52. The calculation results of E ¯ are distributed between 0.6 and 1. The calculation results of P d ¯ are distributed between 0.9 and 1. When P ¯ - η - E ¯ - P ¯ d and P ¯ - E ¯ - P ¯ d are optimized, deviation indexes obtained by using LINMAP decision-making are the smallest and the best among all optimization results. Multi-objective optimization algorithm is an optimization method to solve multiple conflicting objectives by simulating the competition mechanism in nature. It can find a balance point among multiple objective extremes and thus improve comprehensive performance of Diesel cycle.

Reported experiments on Mars include measurements of the speed of sound and its dependence on the atmospheric conditions. Although the conditions of temperature and pressure vary significantly more than on the surface of Earth, it is nevertheless useful to have typical values for these parameters. We note that such typical values of temperature, pressure and air density should be presented carefully to be consistent with the constraint of the ideal gas law.

PurposeThis article aims to find the similarity solutions for the one-dimensional motion of spherical symmetric shock wave in non-ideal gas influenced by the azimuthal magnetic field and monochromatic radiation in the presence or absence of gravitational field. This paper also aims to study the effects of physical parameters on the strength of shock wave, and on the flow variables in the flow-field region behind the shock front.Design/methodology/approachThe Roche model is used to describe the gravitational field effects due to a massive nucleus at the point of symmetry. To derive the similarity solutions, the Lie group symmetry method has been used. Also, the numerical solutions to the present problem are obtained by using Rung–Kutta method of the fourth order with the use of Mathematica software. The effects of variation in the parameter of non-idealness of the gas, the gravitation parameter, the strength of the ambient magnetic field and the adiabatic index of the gas on the shock wave, and on the flow variables is discussed. A comparative study between with and without gravitational field is also, made.FindingsFor different choices of the arbitrary constants that appeared in the solution of infinitesimal generators, we have obtained seven distinct cases of similarity solutions. In the absence of the gravitational field, the similarity solution exists to the power and exponential law shock paths, but in the presence of gravitational field, the similarity solution exists to the power law shock path case only. In the absence of gravitational field, the shock strength is enhanced in the exponential law shock path case in comparison to the power law shock path case. It is found that the shock wave decays with an increase in the value of the adiabatic exponent, the strength of magnetic field, non-idealness of the gas or gravitational parameter.Research limitations/implicationsThe consideration of medium under the influence of gravitational field due to a heavy nucleus at the center and presence of magnetic field decrease the shock strength. This result may be helpful in designing space vehicle and jet engine.Practical implicationsThe result of the present study may be used in the analysis of data from the measurements by space craft in the solar wind and in neighborhood of the Earth’s magnetosphere.Social implicationsThe obtained results may be used for mankind.Originality/valueThe study of spherical shock wave propagation influenced by monochromatic radiation and azimuthal magnetic field in a non-ideal gas with or without gravitational field has yet to be discussed by any authors by using the Lie group symmetry method. In this article, we have discussed all possible cases of similarity solutions using the Lie group symmetry method, which is not studied by anyone as known to us.

The rising number of applications of the organic Rankine cycle (ORC) or supercritical CO2 (sCO2) power systems have shaped a new branch of fluid mechanics called non-ideal compressible fluid dynamics (NICFD). This field of fluid mechanics is concerned with flows of vapors or gases, which are characterized by substantial deviations from the perfect gas model. In extreme cases, even non-classical gas dynamic phenomena could occur. Although these non-ideal compressible flows are the subject of sophisticated numerical simulation studies today, there is also a growing need for experimental data for validating purposes. In the last couple of years, new experimental test rigs designed for investigating non-ideal compressible fluid dynamics have been developed and commissioned. Classical practical measurement techniques are currently being re-developed and applied to non-ideal compressible flows. Despite its substantial relevance, information about these measurement techniques and their differences from conventional methods in the open literature is scarce. The present review article is an attempt to reduce that gap. After briefly discussing the thermodynamics and fluid dynamics of non-ideal compressible flows, the currently available test rigs and their utilized measurement techniques are reviewed. This review discusses schlieren optical investigations, pneumatic and laser-optical methods, and hot-wire anemometry for non-ideal compressible flows.

Variation in predation can have important consequences for predators and prey, but little is known about associated mechanisms. Diel interactions between predators and prey are commonly assumed to be influenced by movement speeds of both predators and prey individuals, sensu the ideal gas model, but the influencing factors of diel predation dynamics have yet to be empirically examined. In this study, we apply principles of the ideal gas model to predict diel variation in kill frequency of moose (Alces alces) by wolves (Canis lupus) in northern Ontario, Canada based on GPS radio‐telemetry data combined with field verification of kills. We used GPS telemetry data from wolves and moose combined with a unique data set on the diel pattern of wolf kills to test whether predator movement rate, prey movement rate, and ambient light condition influence diel variation in kill rates of wolves on moose. Our results indicate that the kill rate between wolves and moose was principally related to the effective movement rate of predators and prey, as predicted by the ideal gas model. We found little evidence that light conditions had any effect on kill rates, but rather the majority of kill rate variation corresponded to wolf movement rate, which was over an order of magnitude higher than that of moose. Lay Summary

We propose a correspondence between the partition functions of ideal gases consisting of both bosons and fermions and the algebraic bases of supersymmetric polynomials on the Banach space of absolutely summable two-sided sequences ℓ1(Z0). Such an approach allows us to interpret some of the combinatorial identities for supersymmetric polynomials from a physical point of view. We consider a relation of equivalence for ℓ1(Z0), induced by the supersymmetric polynomials, and the semi-ring algebraic structures on the quotient set with respect to this relation. The quotient set is a natural model for the set of energy levels of a quantum system. We introduce two different topological semi-ring structures into this set and discuss their possible physical interpretations.

Influence of magnetic field on the propagation of shock waves in radiation gasdynamics is analysed by using wavefront analysis method. We examined behavior of the waves propagated into the two-dimensional (2-D) steady supersonic magnetogasdynamic flow of non-ideal gas with radiation. The transport equations are derived, which determine the condition for the shock formation. The effect of non-idealness and thermal radiation and their consequences under the influence of magnetic field is studied and examined how the flow patterns of the disturbance vary with respect to the variation in the parameters of the flow. It is found that the presence of a magnetic field plays an essential role in the wave propagation phenomena. Nature of the solution with respect to Mach number is analysed, and it is examined how the shock formation distance changes with an increase or decrease in the value of Mach number. Also, the effect of non-idealness on the shock formation distance is elucidated and examined how the shock formation affects the increase in the value of non-ideal parameter in the presence of magnetic field with thermal radiation.

Using the characteristics of the governing quasi-linear system as the referencing coordinate system in the presence of a transverse magnetic field, the evolution of acceleration waves in a non-ideal relaxing gas has been examined along its characteristic path. It is demonstrated that a linear solution in the characteristic plane can behave non-linearly in the physical plane. We have determined the critical amplitude of the initial disturbance; if the initial amplitude of the compressive disturbance is greater than the critical value, the disturbance must culminate into a shock wave, while if it is less than this value, the disturbance will decay, and no shock formation will happen. We establish the criteria for shock generation and the transport equation that governs the development of weak shock waves. Acceleration waves having planar and cylindrical symmetry are analyzed as their steepening, or flattening is investigated as a function of the non-idealness parameter, relaxation parameter, adiabatic index, and magnetic field strength parameter. In both the planar and cylindrical symmetries, the shock formation process is slowed by increasing the relaxation parameter as well as the magnetic field parameter but accelerated by non-idealness and the adiabatic index. In the ideal gas case with adiabatic exponent γ = 2 , the magnetic field has no effect on the steepening or flattening of the wavefront in both the planar and cylindrical symmetries.

We solve the fractional Liouville equation by using Riemann–Liouville and Caputo derivatives for systems exhibiting noninteger power laws in their Hamiltonians. Based on the fractional Liouville equation, we calculate the density function (DF) of a classical ideal gas. If the Riemann–Liouville derivative is used, the DF is a function depending on both the momentum and the coordinate , but if the derivative in the Caputo sense is used, the DF is a constant independent of and . We also study a gas consisting of fractional oscillators in one-dimensional space and obtain that the DF of the system depends on the type of the derivative.

A systematic method is used to study the problem of propagation of planar, cylindrically symmetric and spherically symmetric shock waves of the one-dimensional motion of an inviscid, self-gravitating, non-ideal interstellar gas cloud. The analytic solution of the problem is resolved, which specifies non-linear behavior in the physical plane. The transport equation, which describes the evolution of weak discontinuity in non-ideal gas is derived. It is observed that the nature of the solution completely depends on the net volumetric cooling rate and self-gravitating parameter. It is observed that an increase in the value of self-gravitating parameter results in delay of process of shock formation and shock forms early when heating dominates cooling in the system. Also, expansive waves take less time to decay in planar geometry as compared to cylindrical and spherical geometries and compressive waves take more time to develop shocks for cylindrical and spherical geometries as compared to planar geometry.