| 1. |
- Khayat, Kamal H., et al.
(författare)
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Field-oriented test methods to evaluate structural build-up at rest of flowable mortar and concrete
- 2012
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Ingår i: Materials and Structures. - : Springer Science and Business Media LLC. - 1359-5997 .- 1871-6873. ; 45:10, s. 1547-1564
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Tidskriftsartikel (refereegranskat)abstract
- Thixotropy of flowable mortar and concrete is an important property that affects stability and form pressure characteristics. The increase in thixotropy can reduce lateral pressure on formwork systems. On the other hand, low thixotropy or a continuous casting is required to eliminate the formation of weak interface between lifts in multilayer casting. Thixotropy can be assessed by determining the rate of structural build-up at rest, which necessitates the use of simple and robust test methods to be quantified. Five field-oriented test methods that can be used for the determination of structural build-up at rest of mortar and concrete are proposed in this paper in an attempt to select a reliable field-oriented test. This includes the inclined plane (IP), portable vane (PV), undisturbed slump spread (USS), cone penetration (CP), and K-slump test methods. The repeatability of these test methods was determined four times using two concrete-equivalent mortars and two self-consolidating concretes (SCC) of different thixotropy levels. The IP, PV, and USS tests showed relative error (RE) values of 0.5-37 %. The CP test was successfully used to determine structural build-up of mortar; however, it was difficult to assess the thixotropy of concrete. The K-slump test exhibited a RE, less than 12 % for SCC mixtures with low thixotropy, but up to 76 % for highly thixotropic SCC. Good correlations were established among the various structural build-up indices determined from the proposed test methods and those determined by rheometric tests using various concrete.
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| 2. |
- McCann, Thu H., et al.
(författare)
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High amylose wheat starch increases the resistance to deformation of wheat flour dough
- 2018
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Ingår i: Journal of Cereal Science. - : Elsevier BV. - 0733-5210 .- 1095-9963. ; 79, s. 440-448
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Tidskriftsartikel (refereegranskat)abstract
- High amylose wheat (HAW) starch has been the focus of a number of nutritional studies, but there is limited information around its effect on the mechanical properties of wheat flour dough. This study investigated the size, shape and packing volume of HAW starch and their effect on the microstructure and rheology of dough. Four flour blends were formulated by adding vital wheat gluten and either HAW or commercial wheat starch to HAW flour to achieve a constant 14% protein content, but varied amounts of HAW starch. A large number of small and irregularly shaped HAW starch granules resulted in a high packing volume per gram of starch. Confocal laser scanning microscopy of optimally mixed doughs correlated the degree of starch granule aggregation with the level of HAW starch in the bi-continuous dough network. Small deformation rheology demonstrated that increased quantities of HAW starch in the dough increased the elastic modulus G′ values. Uniaxial extension measurements highlighted a synergy between HAW starch and sources of gluten proteins resulting in increased strain hardening. The impact of HAW starch on dough rheology was attributed to its irregular shape and large number of small granules leading to greater granule-granule interactions.
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| 3. |
- Ahmed, Saad, et al.
(författare)
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The betrayal of constant power × time : Finding the missing joules of transiently-powered computers
- 2019
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Ingår i: Proceedings of the ACM SIGPLAN Conference on Languages, Compilers, and Tools for Embedded Systems (LCTES). - New York, NY, USA : Association for Computing Machinery. - 9781450367240 ; , s. 97-109
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Konferensbidrag (refereegranskat)abstract
- Transiently-powered computers (TPCs) lay the basis for a battery-less Internet of Things, using energy harvesting and small capacitors to power their operation. This power supply is characterized by extreme variations in supply voltage, as capacitors charge when harvesting energy and discharge when computing. We experimentally find that these variations cause marked fluctuations in clock speed and power consumption, which determine energy efficiency. We demonstrate that it is possible to accurately model and concretely capitalize on these fluctuations. We derive an energy model as a function of supply voltage and develop EPIC, a compile-time energy analysis tool. We use EPIC to substitute for the constant power assumption in existing analysis techniques, giving programmers accurate information on worst-case energy consumption of programs. When using EPIC with existing TPC system support, run-time energy efficiency drastically improves, eventually leading up to a 350% speedup in the time to complete a fixed workload. Further, when using EPIC with existing debugging tools, programmers avoid unnecessary program changes that hurt energy efficiency.
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