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- Glimming, Johan, 1976-
(author)
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Primitive Direcursion and Difunctorial Semantics of Typed Object Calculus
- 2007
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Doctoral thesis (other academic/artistic)abstract
- In the first part of this thesis, we contribute to the semantics of typed object calculus by giving (a) a category-theoretic denotational semantics using partial maps making use of an algebraic compactness assumption, (b) a notion of "wrappers'' by which algebraic datatypes can be represented as object types, and (c) proofs of computational soundness and adequacy of typed object calculus via Plotkin's FPC (with lazy operational semantics), thus making models of FPC suitable also for first-order typed object calculus (with recursive objects supporting method update, but not subtyping). It follows that a valid equation in the model induces operationally congruent terms in the language, so that program algebras can be studied. For (c), we also develop an extended first-order typed object calculus, and prove subject reduction. The second part of the thesis concerns recursion principles on datatypes including the untyped lambda calculus as a special case. Freyd showed that in certain domain theoretic categories, locally continuous functors have minimal invariants, which possess a structure that he termed dialgebra. This gives rise to a category of dialgebras and homomorphisms, where the minimal invariants are initial, inducing a powerful recursion scheme (direcursion) on a complete partial order. We identify a problem that appears when we translate (co)iterative functions to direcursion, and as a solution to this problem we develop a recursion scheme (primitive direcursion). This immediately gives a number of examples of direcursive functions, improving on the situation in the literature where only a few examples have appeared. By means of a case study, this line of work is connected to object calculus models.
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| 3. |
- Jennbert, Kristina, et al.
(author)
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Vorbasse
- 2018
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In: The Oxford Dictionary of Late Antiquity. - 9780198662778 - 9780191744457 ; , s. 1574-1574
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Book chapter (other academic/artistic)abstract
- Gudme [p. 693]; Himlingøje [p. 723]; Lundeborg [p. 926]; Skedemosse [p. 1393]; Vorbasse [p. 1574]; Uppåkra [p. 1541]
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| 4. |
- Kharseh, Mohamad, et al.
(author)
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Sustainable heating and cooling systems for agriculture
- 2011
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In: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 35:5, s. 415-422
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Journal article (peer-reviewed)abstract
- Space heating/cooling systems account for approximately 40% of the global energy consumption. Such systems contribute to global warming by emitting 4×1010 MWh of heat and 3×1010 tons of CO2. There is a general understanding that the way to reduce global warming is a more efficient use of energy and increased use of renewable energy in all fields of the society. Ground-coupled heating/cooling systems, which have proven to make huge contributions in reducing energy consumption in Europe and North America, is here applied for poultry industry in Syria, as an example for the Middle East. There are e.g. 13 000 chicken farms in Syria producing 172 000 tons of meat per year. This industry employs directly almost 150 000 people. The total investments in chicken farming are 130 BSP (2 B). The annual mean air temperature in Syria is 15-18°C with winter temperatures close to freezing during two months. The chickens need a temperature of 21-35°C, depending on age, and the heating of all Syrian chicken plants consume 173×103 tons of coal (1196 GWh). In the summer time, the ambient air temperature in Syria could reach above 45°C. The chicken farms have no cooling systems since conventional cooling system is too expensive. The elevated temperature inside the farms reduces the chicken growth and lots of chicken die of overheating. The ground temperature at 10 m depth is roughly equal to the annual mean air temperature. Using the ground as a heat source means a sustainable and less expensive heating of the chicken farms. During the summer, the ground is used as a source for free cooling, i.e. used directly for cooling of the plants without any cooling machines. Current study shows the design and simulated operation of a ground-coupled heating/cooling system for a typical chicken farm in Syria. Performed national potential study showed that the implementation of such ground coupled heating and cooling systems in the Syrian poultry sector would mean increased poultry production and considerable savings in money, energy, and the environment.
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| 5. |
- Scotti, Fernando Matos, et al.
(author)
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Thermal management in WAAM through the CMT Advanced process and an active cooling technique
- 2020
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In: Journal of Manufacturing Processes. - : Elsevier Ltd. - 1526-6125. ; 57, s. 23-35
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Journal article (peer-reviewed)abstract
- Thermal management is a key factor in wire + arc additive manufacturing (WAAM) in order to mitigate heat accumulation and cope with limitations regarding deposition cycle, geometry issues, and mechanical property anisotropies. From the process point of view, the variable polarity Cold Metal Transfer process, a variant of the Gas Metal Arc (GMA) deposition process named as CMT Advanced, stands out as a prominent option to reduce the heat transferred to the layers under deposition, without dropping the deposition rate. In another front, thermally managing the component by employing a technique called Near Immersion Active Cooling (NIAC) throughout all the deposition time has shown to be a promising tool to remove heat from the part under construction. Thus, the current work proposes an evaluation of the CMT Advanced process combined with the NIAC technique for WAAM. The deposition of Al alloy wall-like preforms was made by varying the positive and negative polarity ratio (EP/EN) in the CMT Advanced process and the layer edge to water distance (LEWD) in the NIAC technique. Comparative runs were made with natural cooling instead of the NIAC technique. Electric signals and porosity were quantified to verify the constancy of the process. Thermal cycles of a fixed point of the walls and some of their geometrical features were measured to see the effect of the EP/EN and LEWD parameters in terms of thermal management performance. For the deposition circumstances applied, minor lack of coalescence between layers and also adjacent discontinuities appeared in the waviness valleys of the walls. Such occurrences justified optical and scanning electron microscopy examinations at these locations as complement analyses. Even so, the results clearly showed that the EP/EN parameter is more influential in the control of the layer dimensions and of the preform surface waviness. The LEWD parameter has more effect on reducing the heat accumulation and, consequently, assuring no wall widening as the number of deposited layers is increased. Finally, it was inferred that the possibility of affecting the thermal cycles and geometries of the resultant preforms with two independent thermal management tools expands the windows for finding optimal deposition parameters in WAAM. © 2020 The Society of Manufacturing Engineers
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