Efrén Moreno Benavides

• PhD in Aeronautical Engineer, Physicist
• Universidad Politécnica de Madrid

For several decades, researchers have successfully computed surface burnback to perform complex analyses and simulations related to the combustion of solid propellants. Many of these methods are heuristic or empirical, lacking a rigorous foundation, whereas others introduce numerical issues not related with the involved physics. This paper establis...

This article presents a novel mathematical model to describe the spread of an infectious disease in the presence of social and health events: it uses 15 compartments, 7 convolution integrals and 4 types of infected individuals, asymptomatic, mild, moderate and severe. A unique feature of this work is that the convolutions and the compartments have...

Frame creation (framing) faces the challenge of envisioning novel viewpoints that point to value. This paper examines framing and uses Dorst’s definition of frame from the perspective of engineering design theories and methods to highlight three of their key characteristics: (P1) problem-domain independence, (P2) generativity, and (P3) formal defin...

This article reports a first update on the assesment of the model previously presented in arXiv:2003.13890v1. New available data have been used to feed the model and the comparison with real data still shows good agreement. The main novelty of the model is that it keeps track of the date of infection of a single individual and uses stochastic distr...

The aim of this study is to propose a set of necessary and sufficient conditions for robustness. To this end, a set of definitions and a postulate about unpredictable variability and uncertainty are presented, proving that minimising the number and strength of dependences is a sufficient and necessary condition for robustness and value. They also p...

Whereas the laws of physics establish the relationships between functional requirements, constraints, and design parameters, Axiomatic Design establishes the conceptual principles that drive the engineer’s decisions toward a leader product. Hence, Axiomatic Design appears as a natural kernel of any strategic product design activity. According to Ax...

In most of the existing solar airplanes, solar cells are allocated on the top of the wing. From the perspective of Axiomatic Design, this configuration creates a dependency between power, endurance and wing load. The aim of this article is to present a preliminary formulation of the design problem with quantitative transfer functions to which Suh's...

This study presents a set of definitions and properties that characterize the Ideal Design Process and the resources consumed during this process. As an application of both characterizations, the impact of preliminary decision-making tools in the consumption of resources and its uncertainty is introduced, deriving the conditions that a preliminary...

This paper proposes a model for characterizing the flow pattern of a centrifugal impeller attending to the severity of the reverse flow. The model assumes 1) a definition of an escaping particle as the one that flows in every operational point from the trailing edge towards the leading edge of the impeller blades, and 2) a characterization of flow...

This article applies general engineering rules for describing the reliability of devices working under variable stresses. The approach is based on imposing completeness and physicality. Completeness refers to the model's capability for studying as many stated conditions as possible, and physicality refers to the model's capability for incorporating...

We need to know what sustainability is, before it can be achieved. How must sustainability be defined? Fuzzy Ethics describes a new moral criterion which locates ethics in the physical world and, based on it, proposes a new definition of sustainability that generalizes concepts from engineering, physics, and ethics. This book has two main parts. T...

The two previous chapters discussed the main characteristics and ingredients of the design process. Although these ingredients are difficult to generalize, N. P. Suh (1990) found a common core in what came to be known as Axiomatic Design. His objective, as he himself describes it (Suh, 1990: 4), is to establish a scientific basis for design. The re...

Whether or not the information is useful depends greatly on the ‘level of pragmatism’. See Section 2.8.

The author does not know of any reference where this theorem is stated and proven.

Recently, a theoretical criterion to calculate the stability of an axial-flow compressor rotor has been presented in the scientific literature. This theoretical criterion was used for determining the locus of the stability line over the rotor map and for predicting the post-stall evolution of the constant-speed line of a rotor. The main objective o...

Recently, an analytical model to calculate the stability of an axial-flow compressor rotor has been presented in the scientific literature. The range of validity of that theoretical characterization was supported by several lemmas and theorems. One of the main results was the definition of a dimensionless coefficient for determining the location of...

This book provides engineers and students with a general framework focusing on the processes of designing new engineering products. The procedures covered by the framework lead the reader to the best trade-offs to ensure maximum satisfaction of the customer's needs, meeting the lowest cost expectations, ensuring the lowest environmental impact and...

The stability of 595 operational points, belonging to 25 different experimental arrangements of the NASA stage 57, is studied by means of a theoretical calculation based on a theorem recently presented in the scientific literature. This large number of tests is used for checking the results of the theory for a wide variation of the operational and...

This article explores the potential of Moiré deflectometry for measuring the temperature field in quasi-two-dimensional small scale flows. The research shows that digital Moiré deflectometry combined with two-dimensional Fourier transform for phase map extraction constitutes a useful diagnostic tool for acquiring the fluid temperature with sufficie...

We propose a reliability model for describing the lifetime of devices and materials working under variable stress (i.e., stresses which are a function of time). The model is based on a two-parameter Weibull distribution obtained by retaining the leading term from a series expansion of a general cumulative hazard function. The scale parameter is rel...

Moiré deflectometry is a robust and simple optical method that allows obtaining the temperature field in flows with uniform pressure and two-dimensional and axisymmetric flows. Since in real configurations it is not possible to keep exactly the hypothesis of two-dimensional flow, it is necessary to asses this influence. Therefore this work studies...

Hoy en día los ordenadores digitales permiten procesar una gran cantidad de operaciones a gran velocidad. Esta rapidez de cálculo ha contribuido a que prácticamente todos los equipos diseñados, construidos y ensayados en todas las ramas de la ingeniería tiendan a evaluarse mediante su simulación en ordenador. Las ventajas de este procedimiento son...

The paper presents a theoretical model of convective heat exchangers working with internal pulsating flows. It aims for a better physical understanding of the processes leading to a heat transfer enhancement inside these devices. When the frequency of the pulsation is increased, some geometries exhibit a maximum response, measured by its temperatur...

The stability of 595 operational points belonging to 25 different experimental arrangements of the NASA rotor 57 is studied by means of a theoretical calculation based on a theorem recently presented in the scientific literature. This large number of tests is used to check the results of the theory for a wide variation of operational and design par...

The article describes an analytical model to calculate the stability of axial-flow compressor rotors. It illustrates how stability is related to the ratio of two times. The definitions of both times are obtained in a rational way for high-performance rotors subjected to non-small disturbances, and a theoretical stability margin coefficient is estab...

When considering economic aspects, recent work has shown that 100% hydrogen fueled airplanes will not be feasible for at least several decades. This paper analyzes some of the technological topics involved in the use of hydrogen as additional fuel in conventional kerosene fueled aircrafts. The addition of limited quantities of hydrogen does not req...

A physical limit to the minimum reachable size of a thermoacoustic engine has been obtained. It aims for a better physical understanding of the influence of the gas behavior in the energy dissipation of such smallest devices, and it is based on physical considerations about pipes of large aspect ratios. The solution depends on the gas properties an...

A very simple formula has been developed to calculate the minimum number of blades of an axial-flow compressor in the early design stage. It is based on the comparison of two characteristic times and does not need any adjusting value to fit experimental results from open literature. The formula obtained relates loading and flow coefficients, tangen...

This paper presents a theoretical model of thermoacoustic engines. It aims for a better physical understanding of the power production of these devices. The main idea that supports the work is that the power output emerges from a thermodynamic cycle. The fluid near the heat exchangers is assumed to follow a thermodynamic cycle such as in a closed c...

In Diesel engines equipped with jerk injection pumps there appear many effects derived from fuel compressibility and the short duration of injection. As a result of them, cavitation, secondary injection, dribble and other hazardous phenomena may occur. With the objective of studying these processes, a simulation model for an indirect Diesel injecti...