We have systematically studied the effects that non‐Maxwellian ion velocity distributions produce on the ionic part of the spectrum of radar waves incoherently scattered from the disturbed high‐latitude ionosphere in the upper E and lower F regions. For ion to electron temperature ratios smaller than or equal to unity and electric field strengths greater than about 70 mV/m the spectrum is seriously distorted from the shape that it would normally have if the ion velocity distribution were Maxwellian. In events where the magnetospheric convection electric field exceeds 70 mV/m the interpretation of the data is affected if the erroneous assumption of a Maxwellian distribution is used to analyze the data. The electron temperature is the property most seriously affected by the erroneous interpretation, as it can be underestimated by as much as a factor of 2. Finally, the spectra obtained under disturbed conditions are anisotropic, the least distortions from a Maxwellian‐type spectrum being found along the magnetic field direction. The apparent ion temperature seen along the line of sight of the radar as it scans from parallel to the magnetic field to nearly perpendicular to the magnetic field also increases as the angle with the magnetic field increases, even for dc electric field strengths as small as 20 mV/m.

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A novel realistic Work Criteria Function (WCF) approach has been used to analyze the ideal air-standard Diesel cycle. The WCF formulation gives rise to a new performance criterion which is termed as efficient power density (EPD). Thermodynamic analysis under maximum efficient power density (MEPD) conditions has been performed and compared with other available performance criteria using variable specific heats of the working fluid. The results obtained from this analysis prove that the engine designed under MEPD conditions is very efficient and the size of the engine is reduced significantly compared to those designed under maximum efficient power (MEP), maximum power density (MPD), and maximum power (MP) criteria. Harmful emissions like {\mathrm{NO}_{\mathrm{x}}} may decrease considerably at higher values of the maximum cycle temperature ratio (ξ). The effect of variable specific heats of operational fluid on the actual cycle’s performance has a significant impact on engine performance and should be incorporated when evaluating practical cycle engines. The results obtained in the current study have scientific importance and could be an essential guide for the design of real Diesel engines by engine manufacturers.