O toque e a diferença : um estudo da emergência criadora na formação do intérprete contemporâneo

Doutoramento em Motricidade Humana, especialidade de Dança.Este estudo analisa o lugar do corpo sensível na formação do intérprete contemporâneo à luz dos conceitos de toque e de diferença. A investigação partiu do encontro entre estes dois conceitos que, inicialmente, refletem modos distintos de pensar a vida sensível. Por um lado, o toque como tato, como sentido do tangível, estatui-se ao mesmo tempo como o mais difícil de definir entre todos os sentidos, pela sua duplicidade e plasticidade. O toque apresenta duas dimensões: uma focada, local, coincidente com os contornos objetivos do contacto físico; outra mais difusa, global, que se estende interiormente a todo o corpo. Este toque interno do corpo tem sido objeto de explorações filosóficas intensas seja como “sentido dos sentidos”, o sentido no qual convergem todos os outros na apreensão complexa da realidade, mas também como fundo percetivo que sustenta a perceção de si e o sentimento de existência. Por outro lado, a diferença é o conceito pelo qual Gilles Deleuze pensa a vida sensível do ponto de vista das relações de força que a fundamentam. A diferença é o que permite acolher o movimento de forças que constituem o mundo concreto “entre” e “para além” das formas organizadas. Deleuze fala de um “puro sensível”, um “ser do sensível” que excede o sensível sentido e representado, e que se manifesta por uma espécie de “mouvance”, “uma diferença na intensidade”, uma variação contínua da matéria, que leva o existente, a vida, a diferir perpetuamente de si mesmo. As noções de toque e de diferença revelam-se regimes de exploração da vida sensível à partida distintos: o campo da intencionalidade e da experiência vivida; o campo intensivo da experimentação, o plano da vida vivida e não reconhecida. O intérprete encontra-se numa posição paradoxal: a sua pesquisa obriga-o a gerir constantemente análise e imersão, a situar-se entre o plano de experimentação e o plano da experiência. Ele deve gerir dois estados de presença que parecem, à primeira vista, excluir-se um ao outro. No nosso estudo, para além da tensão epistemológica inicial, este binómio configura um campo para a exploração prática da emergência criadora onde o toque é encarado como o elemento técnico que pode ligar e tornar mais percetíveis as vias de passagem entre o campo da experiência e o campo da experimentação, os procedimentos que permitem a transição do corpo intencional ao corpo intensional. Finalmente, a reflexão que move o presente estudo assenta numa intensa prática pedagógica onde as noções de toque e diferença operam não apenas como conceitos mas como ferramentas práticas, quadros de experiência concretos, para a abertura intensiva do corpo.ABSTRACT: This study analyses the place of the sensitive body within the training of contemporary performers in the light of the concepts of touch and difference. The investigation consequently started with these two concepts, which, initially, reflect distinct modes of thinking the sensitive life. ! One one hand, touch as tact, as the sense of the tangible, simultaneously being the most difficult to define amongst all senses due to its duplicity and plasticity. The touch presents two dimensions: a focus, local, coinciding with the objective contours of the physical contact; and another, more diffuse, global, which extends internally throughout the entire body. This internal touch of the body has been an object of intense philosophic exploration, whether as "sense of the senses", the sense in which all the others converge in the apprehension of reality, or as percipient background sustaining perception of oneself and the feeling of existence. ! On the other hand, the difference is the concept employed by Gilles Deleuze to think the sensitive life from the viewpoint of the forces that comprise its foundation. The difference is what allows receiving the movement of the forces that constitute the concrete world "between" and "beyond" the organized forms. Deleuze talks about a "pure sensitive", a "sensitive being", which exceeds the sensed and represented sensitive, which manifests as a kind of "mouvance", "a difference in intensity", a continuous variation of matter, which causes the existing, the life to differ perpetually from itself. ! The notions of touch and difference reveal to be two essentially distinct regimen of exploring the sensitive life: the field of intentionality and the lived experience; and the field of intense experimentation, the level of lived yet not recognized life. ! The performer faces a paradoxical situation: his research obliges him to constantly balance analysis and immersion, to situate himself between the plane of experimentation and the plane of experiencing. He must balance two states of presence, which at first sight seem to mutually exclude one another. In our study - beyond the initial epistemological tension - this binomial configures a field for the practical exploration of the creative emergence where the touch is considered a technical element that can connect and make the passages between the plane of experimentation and the plane of experiencing more perceptible, as well as the procedures which allow the transition from the intentional to the intensional body. ! Finally, the reflection at the core of the present study is based on intense pedagogical practice, in which the notions of touch and difference not only operate as concepts, but as practical tools, as concrete experiential dimensions facilitating an intense opening of the body.FCT - Fundação para a Ciência e a Tecnologi

Determination of the compressor optimal working conditions

The replacement of environmentally unfriendly refrigerants and the energy saving demand have recently caused changes of the components and operation of the vapour compression plants; in particular, the compressors have been experiencing upgrades and modifications. The compression systems are usually designed for working under maximum load conditions, but most of the time these plants work under partial load conditions with compressor on–off cycles regulated by a thermostat. As for the variable speed compressor, the speed is continuously controlled to match the compressor capacity to the load required; this allows to save energy when compared to the thermostatic control. The aim of this paper is to identify the compressor current frequency that optimizes the energy, exergy and economy aspects. The determination of the optimum frequency for each working condition is key to build a control algorithm that allows the compressor speed to be continuously regulated by an inverter. This analysis has been applied to the reciprocating and scroll compressors and high energy savings have been achieved

Exergy analysis of a cooling system: experimental investigation on the consequences of the retrofit of R22 with R422D

In this article, the performances of a walk-in air cooler working with R22 and its substitute R422D are experimentally studied. To define a full comparison on the performance characteristics of R22 and R422D, both an energetic and an exergetic analyses are proposed. The experimental investigation was carried out considering four levels of refrigeration capacity: 920, 1340, 1925 and 2250 W. All tests were run at steady-state conditions and by keeping the value of the external air temperature equal to 22°C. The experimental analysis allowed the determination of the COP, the exergetic efficiency, the exergy flow destroyed in each component and other variables characterizing the working of the plant. The results demonstrated that COP of R422D is, on average, 20% lower than that of R22. Furthermore, for plant whose condenser is air cooled, R422D could lead to increase the fan speed or to adopt bigger blowers

Performances of thermostatic and electronic valves controlling the compressor capacity

The performance of the energy consumption of an electronic valve and a classical thermostatic valve has been compared when these expansion valves are adopted in a vapour compression plant subjected to a cold store. The main aim is to verify experimentally which type of expansion valve would be preferable from energy point of view when a classical thermostat or a fuzzy logic algorithm are used as the control system for the refrigeration capacity. The fuzzy logic-based control is able to modulate continuously the compressor speed through an inverter. The results show that with a fuzzy algorithm, the thermostatic expansion valve allows an energy saving of about 8% in comparison with the electronic valve. When on–off control is used, the electric energy consumption obtained both with the electronic valve and with the thermostatic valve is comparable

Analysis of some recharge solutions on varying the R407C composition

In the vapour compression plants possible leaks can vary the composition of a zeotropic refrigerant mixture. The main aim of this paper is to verify experimentally if the plant performances are restored with a proper recharge, when leaks are imposed. As for the R407C mixture the percentage of the less volatile component (R134a) increases, while the percentage of the more volatile components (R32 and R125) decreases when leaks occur. The experimental tests have been realized determining refrigerant leaks from the liquid receiver placed at the condenser outlet and measuring the properties in steady state condition. The recharge is realized in different ways: with R407C, with R134a and R410A or with R32 R125 and R134a. The different solutions are then compared from the economical point of view, in terms of COP, refrigeration power and air temperature at the evaporator outlet, adopting an iteration method. This method determines the real composition of a zeotropic mixture working in a compression plant, when only the temperature and pressure values at the expansion valve inlet and outlet are known

A two-dimensional model of a solid-state regenerator based on combined electrocaloric-elastocaloric effect

Abstract Solid-state refrigeration technologies are considered nowadays emerging alternative to vapor compression refrigeration. In this paper is introduced a two-dimensional model of solid-state refrigerator, which employs materials experiencing a combined electrocaloric-elastocaloric effect and it operates at room temperature. A numerical investigation is performed to explore the energetic performance of the refrigerators. The results reveal that PbTiO 3 as elastocaloric refrigerant confers the best performances in terms of COP; the highest cooling power estimated are proper of combined elastocaloric-electrocaloric effect, with increments around +65% than employing PbTiO 3 in single electrocaloric/elastocaloric refrigeration, on equal operative conditions

A Flexible Top-Down Numerical Modeling of an Air-Cooled Finned-Tube CO2 Trans-Critical Gas Cooler

Carbon dioxide trans-critical refrigeration systems have been deeply investigated over the last years, with the aim to improve their performance by using several possible technical solutions. However, most of them lead to a more complex and expensive system, and therefore a trade-off is always needed to identify the best viable solution. Therefore, many efforts have also been focused on the study of a critical component of the basic carbon dioxide trans-critical cycle, which is the gas cooler, especially by numerical simulations. This work shows a new flexible approach to numerically model an air-cooled finned-tube CO2 trans-critical gas cooler integrating a Top-Down methodology with a Finite Difference Method to solve the governing equation of the thermodynamic processes involved. The model was developed to reproduce the behavior of an experimental CO2 refrigeration system, which provided the experimental data used for its validation. In detail, the model showed a good agreement with the experimental data, with average deviations of 1 K (0.3%), 0.9 bar (1%) and 0.15 kW (2.8%) regarding the refrigerant outlet temperature, the refrigerant outlet pressure and the rejected heat, respectively. The Top-Down numerical approach slightly outperformed the performance of previous numerical models available in the literature. Furthermore, the analysis of the refrigerant temperature and pressure along the tubes and rows also shows that the model can reproduce their behavior consistently and accordingly to data reported in the literature. The proposed approach can be used for detailed thermo-economic analysis of the whole refrigeration system, with the aim to optimize the design of the gas cooler

An evaluation of R22 substitutes performances regulating continuously the compressor refrigeration capacity

This paper presents the results of an experimental analysis which compares in terms of energetic performances the refrigeration capacity control obtained by means of a variable-speed compressor with the on/off control deriving from a classical thermostatic device. The compressor considered is semi-hermetic reciprocating and is a component of a vapour compression refrigeration plant subjected to a commercially available cold store. The compressor working with the fluids R22, R507 and R407C and designed for a revolution speed corresponding to the compressor supply current nominal frequency of 50 Hz, has been tested varying the frequency in the range 30–50 Hz. In this range, the most suitable working fluids proposed as substitutes of the R22 as the R407C (R32/R125/R134a 23/25/52% in mass), the R507 (R125/R143A 50/ 50% in mass) and the R417A (R125/R134a/R600 46.6/50/3.4% in mass) have been tested. The results show that, using the R407C, it is possible an average an electric energy consumption about 12% smaller when an inverter is employed to control the compressor refrigeration capacity instead of the thermostatic control which imposes on/off cycles on the compressor, working at the nominal frequency of 50 Hz. So the R407C confirms its superiority in comparison with the R417A and R507; only the R22 shows a better performance

Refrigeration plant exergetic analysis varying the compressor capacity

The paper presents an exergetic analysis of a vapour compressor refrigeration plant when the refrigeration capacity is controlled by varying the compressor speed. The aim is performance evaluation of both the whole plant and its individual components. The analysis of the exergy flow destroyed in each device of the plant varying the compressor speed has been carried out in order to determine the relative irreversibility of the plant components. The vapour compression plant is subjected to a commercially available cold store. The compressor working with R22, R407C and R507 and designed for a revolution speed corresponding to 50 Hz supply current frequency, has been used varying the frequency in the range 30–50 Hz. In this range, the most suitable working fluids proposed as substitutes of R22, as R407C (R32/R125/R134a 23/25/52% in mass), R507 (R125/R143A 50/50% in mass) and R417A (R125/R134a/R600 46.6/50/3.4% in mass), have been tested. The variable-speed compressor is fitted with a pulse-width modulated source inverter (PWM) predominantly used in medium power applications due to its relatively low cost and high efficiency. The basic difference between variable speed refrigeration and conventional refrigeration systems is in the control of the system capacity at part-load conditions. The conventional refrigeration systems are characterized by compressor on/off cycles arising from by the thermostatic control. On the contrary when the inverter is used the capacity of the refrigeration system is matched to the load regulating the compressor motor speed. When the control of the compressor capacity is obtained by varying its speed there is an energy saving with respect to the thermostatic control. The best results of the exergetic analysis have been obtained using R22 followed by the non-azeotropic mixture designed as R407C that confirms, among the fluid candidates R22 substitution a better performance, shown also at the compressor nominal speed. Copyright © 2003 John Wiley & Sons, Ltd

HFO1234ze as Drop-in Replacement for R134a in Domestic Refrigerators: An Environmental Impact Analysis

Abstract In this paper are reported the results of an experimental comparative analysis between R134a and HFO1234ze, when they are employed as refrigerants in a domestic refrigerator. Under sub-tropical conditions, it have been measured the energy consumptions in accordance with the UNI-EN-ISO15502. For each experiment it have been estimated both the TEWI and the Life Cycle Climate Performance indexes to assess the environmental impact due to HFO1234ze when used in place of R134a