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- Lund Ohlsson, Marie, et al.
(författare)
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Least Squares Approach to Inverse Problems in Musculoskeletal Biomechanics
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Inverse simulations of musculoskeletal models computes the internal forces such as muscle and joint reaction forces, which are hard to measure, using the more easily measured motion and external forces as input data. Because of the difficulties of measuring muscle forces and joint reactions, simulations are hard to validate. One way of reducing errors for the simulations is to ensure that the mathematical problem is well-posed. This paper presents a study of regularity aspects for an inverse simulation method, often called forward dynamics or dynamical optimization, that takes into account both measurement errors and muscle dynamics. The simulation method is explained in detail. Regularity is examined for a test problem around the optimum using the approximated quadratic problem. The results shows improved rank by including a regularization term in the objective that handles the mechanical over-determinancy. Using the 3-element Hill muscle model the chosen regularization term is the norm of the activation. To make the problem full-rank only the excitation bounds should be included in the constraints. However, this results in small negative values of the activation which indicates that muscles are pushing and not pulling. Despite this unrealistic behavior the error maybe small enough to be accepted for specific applications. These results is a starting point start for achieving better results of inverse musculoskeletal simulations from a numerical point of view.
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| 3. |
- Smolicki, Jacek, 1982-
(författare)
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Timescapes of Białowieża
- 2023
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Ingår i: Testing Ground 04. - London : Independently published. - 9798854865531 ; , s. 8-15
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- ISSUE 04: SUPRA SCALAR In about 5 billion years the Sun is expected to become a red giant that will expand to engulf the Earth, wiping out all life. Within the next 15,000 years, the precession of the Earth’s poles may move the North African Monsoon far enough north to transform the Sahara Desert into a tropical rainforest. Shifting baselines over the last two centuries have masked rapid declines in biodiversity and an accelerating climate crisis. In contrast, today, the decisions that define our worlds are limited by political terms, news cycles, and quarterly profits – facilitated by accelerating technologies and challenged by shortening attention spans. However, what if we collectively commit to dimensions of time, energy, and distance outside of our current understanding? How could these alternative perspectives reshape our worlds?Supra Scalar, the fourth issue of TESTING-GROUND, explores landscapes at extremes of time and space. Questioning the knowledge and methodologies needed to engage with unfamiliar temporalities, with landscapes beyond conventional lines of sight, and with worlds accepted as less-than-human.
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| 5. |
- Wiklund, Ingela
(författare)
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We have had remarkable success
- 2013
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Ingår i: Sexual & Reproductive HealthCare. - : Elsevier BV. - 1877-5756 .- 1877-5764. ; 4:2
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Tidskriftsartikel (refereegranskat)
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