Search results

The application of dry-type transformers is growing in the market because the technology is non-flammable, safer and environmentally friendly. However, the unit dimensions are normally larger and material costs become higher, as no oil is present for dielectric insulation or cooling. At designing stage, a transformer thermal model used for predicting temperature rise is fundamental and the modelling of cooling system is particularly important. This paper aims to describe a thermal model used to compute dry transformers with different cooling system configurations.

The paper introduces a fast-calculating thermal and pressure network model for dry-transformer cooling systems, preliminarily verified by analytical methods and advanced CFD simulations, and finally validated with experimental results.

This paper provides an overview of the network model of dry-transformer cooling system, describing its topology and its main variants including natural or forced ventilation, with or without cooling duct in the core, enclosure with roof and floor ventilation openings and air barriers. Finally, it presents a formulation for the new heat exchanger element.

The network approach presented in this paper allows to model efficiently the cooling system of dry-type transformers. This model is based on physical principles rather than empirical assessments that are valid only for specific transformer technologies. In comparison with CFD simulation approach, the network model runs much faster and the accuracies still fall in acceptable range; therefore, one is able to utilize this method in optimization procedures included in transformer design systems.

The purpose of this paper is to present a method for thermal computations of power devices based on a coupling between thermal and pressure networks. The concept of the coupling as well as the solution procedure is explained. The included examples demonstrate that the new method can be efficiently used for design of transformers and other power devices.

The bidirectional propagation of temperature signal is introduced to the pressure network, which enables control of the power flow and a close coupling to the thermal network. The solution method is based on automatic splitting of the network definition (netlist) into two separate networks and iteratively solving the model using the Newton-Raphson approach as well as the adaptive relaxation enhanced by the direction change control.

The proposed approach offers reliable convergence behaviour even for models with unknown direction of the fluid flow (bidirectional flows). The accuracy is sufficient for engineering applications and comparable with the computational fluid dynamics method. The computation times in the range of milliseconds and seconds are attractive for using the method in engineering design tools.

The new method can be considered as a foundation for a consistent network modelling system of arbitrary thermodynamic problems including fluid flow. Such a modelling system can be used directly by device designers since the complexity of thermodynamic formulations is encapsulated in predefined network elements while the numerical solution is based on a standard network description and solvers (Spice).

Although writings in the fashion forecasting field often mention the connections between industry and culture, it still requires further clarifications in a context of uncertainty, fast pace changes and a high volume of information. This paper aims to explore fashion as a material culture to discuss forecasting roles in different stages of dialogue between culture and industry.

This paper explores the cultural aspects of fashion to discuss multiple roles of forecasting and its implications in the fashion system from a multidimensional perspective that interlaces culture and industry in contemporary contexts through a literature review in fashion forecasting and material culture. Recent nonacademic articles were also reviewed in order to highlight fresh perspectives in the field.

The literature review demonstrates that there are two main lines of reasoning in trend forecasting. First, trend forecasting as a cultural and predictive practice focused on understanding emerging shifts in the culture and translating them to the industry. The second approach considers trend forecasting as a strategic and curatorial practice that not merely predicts consumer's behaviors and preferences but intentionally acts as a filter of all the available possibilities curating and narrowing them down to organize the market around assertive information reducing financial losses risk. This article proposes an integration between the two perspectives – from culture to industry – in a contemporary context where consumers' tastes and preferences have become increasingly diverse, and early diffusion theories can no longer explain fashion spread.

Further investigations of contemporary and potential future trend forecasting roles and aspects could benefit from in-depth interviews and focus groups with industry experts, consumers and academics.

The paper intends to approximate theoretical reflections of fashion as a material culture to the current industry context.

It contributes to the studies of fashion forecasting, providing an overview of its development, roles and objectives, both from the industrial and material culture perspectives, which culminates in a framework that summarizes its intricate mechanisms.

The purpose of this article is to introduce the theme of this special issue. In doing so, the paper argues that marketing historical research is in need of a paradigmatic shift. Rather than privilege primary and secondary sources that preserve the perspectives and actions of corporate managers and of marketing academics, marketing historians need to open the historical narratives they construct much more than before to the experiences and voices of ordinary consumers, i.e. of those who actually shop and buy and choose. They also need to do more to incorporate into their narratives examples of the value-creation that consumers themselves enact, both inside and outside the sphere of the market.

By reviewing the state of the marketing historical literature, this paper introduces the “History from Below” school of historical thought into marketing historical research. It also tests to what extent a stronger consumer focus might be able to enrich historical research in marketing.

Although contemporary marketing historiography is characterized by a richness of themes and methodological approaches, there is still a marked difference between the way marketing academics and historians write the history of marketing and consumption. While, surprisingly, the former often tend to ignore the voices of ordinary consumers, the latter often lack the marketing-related “technical” knowledge to fully understand the significance of specific archival sources they discuss. This means that a genuine “People’s History of Marketing” has yet to be written.

Findings from the paper will be of value to marketing historians who wish to expand the scope and agenda of their research and help historical research move away from narrow managerial perspectives and other “privileged” accounts of marketing.

This paper makes two original contributions. First, it introduces historiographical innovations associated with “History from Below” (social history) into marketing historical scholarship. Second, it attempts to help marketing historians identify alternative sets of primary and secondary sources, e.g. oral history archives, which would allow them to be much more optimistic about their own ability to reconstruct the perspectives of those whose voices are all too often ignored.