Clebsch Potentials in the Variational Principle for a Perfect Fluid

Equations for a perfect fluid can be obtained by means of the variational principle both in the Lagrangian description and in the Eulerian one. It is known that we need additional fields somehow to describe a rotational isentropic flow in the latter description. We give a simple explanation for these fields; they are introduced to fix both ends of a pathline in the variational calculus. This restriction is imposed in the former description, and should be imposed in the latter description. It is also shown that we can derive a canonical Hamiltonian formulation for a perfect fluid by regarding the velocity field as the input in the framework of control theory.Comment: 15 page

Investigating dynamic dependence using copulae

A general methodology for time series modelling is developed which works down from distributional properties to implied structural models including the standard regression relationship. This general to specific approach is important since it can avoid spurious assumptions such as linearity in the form of the dynamic relationship between variables. It is based on splitting the multivariate distribution of a time series into two parts: (i) the marginal unconditional distribution, (ii) the serial dependence encompassed in a general function , the copula. General properties of the class of copula functions that fulfill the necessary requirements for Markov chain construction are exposed. Special cases for the gaussian copula with AR(p) dependence structure and for archimedean copulae are presented. We also develop copula based dynamic dependency measures — auto-concordance in place of autocorrelation. Finally, we provide empirical applications using financial returns and transactions based forex data. Our model encompasses the AR(p) model and allows non-linearity. Moreover, we introduce non-linear time dependence functions that generalize the autocorrelation function

A Variational Principle for Dissipative Fluid Dynamics

In the variational principle leading to the Euler equation for a perfect fluid, we can use the method of undetermined multiplier for holonomic constraints representing mass conservation and adiabatic condition. For a dissipative fluid, the latter condition is replaced by the constraint specifying how to dissipate. Noting that this constraint is nonholonomic, we can derive the balance equation of momentum for viscous and viscoelastic fluids by using a single variational principle. We can also derive the associated Hamiltonian formulation by regarding the velocity field as the input in the framework of control theory.Comment: 15 page

Analysis of rocket engine injection combustion processes

Mixing methodology improvement for the JANNAF DER and CICM injection/combustion analysis computer programs was accomplished. ZOM plane prediction model development was improved for installation into the new standardized DER computer program. An intra-element mixing model developing approach was recommended for gas/liquid coaxial injection elements for possible future incorporation into the CICM computer program

Sedentary behaviors and adiposity in young people: causality and conceptual model

Research on sedentary behavior and adiposity in youth dates back to the 1980s. Sedentary behaviors, usually screen time, can be associated with adiposity. Although the association usually is small but significant, the field is complex, and results are dependent on what sedentary behaviors are assessed and may be mediated and moderated by other behaviors

Open educational practices for curriculum enhancement

Open educational resources (OER) and open educational practices (OEP) are relatively new areas in educational research. How OER and OEP can help practitioners enhance curricula is one of a number of under-researched topics. This article aims to enable practitioners to identify and implement appropriate open practices to enhance higher education curricula. To that aim, we put forward a framework of four open educational practices based on patterns of OER reuse (‘as is’ or adapted), mapped against the processes of curriculum design and delivery. The framework was developed from the in-depth analysis of 20 cases of higher education practitioners, which revealed patterns of OER reuse across disciplines, institutions and needs. For each open practice we offer evidence, examples and ideas for application by practitioners. We also put forward recommendations for institutional policies on OER and OE

Servitisation and value co-production in the UK music industry

Since the rise of music on the internet, record companies have reported falling sales of physical products. This has occurred at a time when technology has radically increased choice, availability and the opportunity for the consumer to purchase music. As the music industry has moved from a product to a service business model, has the loss of sales meant they have not taken their customers with them? This paper provides a description of different music consumers based upon quantitative analysis of consumer characteristics. The paper then undertakes an exploration of the relationship between the consumer groups and their purchasing preference in relation to intangible ‘service’ purchase such as downloaded music and the purchase of a tangible physical product such as CDs or vinyl. In addition, we analyse the relationship between consumer types and their propensity to actively engage with music communities, such as through engagement with social media, and thus their willingness to coproduce greater value. Finally we explore the moderating effects of age and time devoted to listening to music on purchasing preferences and music discovery

Predicción en las ciencias sociales

En treballs anteriors sobre explicació i causalitat en les ciències socials no he prestadola atenció necessària al problema de la predicció. L'objecte d'aquest article eselaborar i aclarir alguns assumptes que concerneixen a la predicció en les ciències socials, especialment quan aquesta s'aplica a les perspectives «interpretativistas».In previous works about explanation and causality in the social sciences, I have not paid enough attention to the problem of prediction. The purpose of this article is to elaborate on and clarify certain issues related to prediction in the social sciences, especially when it is applied to «interpretavist» perspectives.En trabajos anteriores sobre explicación y causalidad en las ciencias sociales no he prestado la atención necesaria al problema de la predicción. El objeto del presente artículo es elaborar y clarificar algunos asuntos que conciernen a la predicción en las ciencias sociales, especialmente cuando ésta se aplica a las perspectivas «interpretativistas»

Lean six sigma implementation, a systematic literature review

[EN] Organizations must be able to meet customer needs in today’s complex market situation and business environment, the needs and essentials for their satisfaction such as high product quality, competitive costs and faster delivery. Organization need to apply a comprehensive concept and method on managing this requirement. This systematic review intends to identify how Lean Six sigma implementation in many industries. Lean Six Sigma (LSS) is a method that has been widely used in research in various fields and continues to grow, to get the most common solution it is necessary to review the method. This research is to observe concept and method still relevant to be use and effectively improved the business performance and customer satisfaction. For the identity of the LSS Papers, a total of 50 research papers were reviewed which met the criteria, Research object, country of research and year of publication and Result of research. 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Implementation of the six sigma method in the educational process. Journal of Physics: Conference Series, 1384(1), 012022. https://doi.org/10.1088/1742-6596/1384/1/012022Kundu, G., & Murali Manohar, B. (2012). Critical success factors for implementing lean practices in IT support services. International Journal for Quality Research, 6(4), 301-312.Li, N., Laux, C.M., & Antony, J. (2019). How to use lean Six Sigma methodology to improve service process in higher education: A case study. International Journal of Lean Six Sigma, 10(4), 883-908. https://doi.org/10.1108/IJLSS-11-2018-0133Maleszka, A., & Linke, M. (2016). Improvement of management process by using Lean Six Sigma tools in some big organisation of food industry. Polish Journal of Natural Sciences, 31(1), 101-112.Motiani, N., & Kulkarni, A. (2019). 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