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Overall Performance of Spent Garnet as Sand Replacement in Self-Compacting Geopolymer Concrete
Published in Habeeb Lateef Muttashar, Sustainable Construction Materials, 2019
Experimental results on water absorption in the early stages (7 days) reveal that it was higher for the SCGPC specimens containing spent garnet than in the control specimen. But as the duration of curing was increased to 90 days, the absorption rate decreased in all the SCGPC specimens. In short, the water absorption of spent garnet-based SCGPC was within acceptable limits at less than 10%. The performance of spent garnet-based SCGPC exposed to carbon dioxide environments showed excellent resistance to rapid carbon dioxide penetration. A negative mass change of the spent garnet-based SCGPC specimen was observed due to acid exposure. SCGPC using spent garnet as replacement for river sand demonstrated lower performance against sulfate attacks.
Central Force Optimization
Published in Nazmul Siddique, Hojjat Adeli, Nature-Inspired Computing, 2017
As explained in Section 3.2, the mass in CFO space is a user-defined objective function's value, not necessarily the fitness value itself. For example, the mass in CFO is defined as U(Mj=1k−Mj=1p)⋅(Mj=1k−Mj=1p)α, that is, the difference in fitness values raised to the α power multiplied by the unit step function U(⋅). The user is free to define some other function as the mass in CFO if the alternative definition provides better results. The unit step function U(⋅) solves the negative mass problem by creating a positive-definite mass. U(⋅) also is the basis for defining a new type of hyperspace directional derivative. In nature, the force of gravity is a conservative vector force field resulting in action at a distance, and accordingly its basic equations are cast in terms of vectors. But real gravity can also be calculated as the gradient of a scalar gravitational potential function, just as the electric field can be derived from an electric potential. The notion of a gradient applies in CFO space as well; but to some degree, its utility depends on how mass is defined.
Physics
Published in Keith L. Richards, Design Engineer's Sourcebook, 2017
The nucleus was considered to be made up of protons of unit mass and carrying a unit positive charge. The electron was thought to have a negative mass but carried a comparative unit negative charge. To explain the difference between observed molecular weight and theoretical molecular weight, it is necessary to postulate the existence within the nucleus of particles other than protons. These were called neutrons, which have a unit mass but no charge.
Negative effective mass, optical multistability and Fano line-shape control via mode tunnelling in double cavity optomechanical system
Published in Journal of Modern Optics, 2019
Vaibhav N. Prakash, Aranya B. Bhattacherjee
Negative masses are not present in the real world but a composite system could give rise to an effective negative mass of components. The concept of effective negative mass is derived from condensed matter physics where an electron ‘gains’ an effective negative mass in the background lattice potential, in a way that its motion is in the opposite direction to the applied force. It has also been argued (23) that effective mass in simple mass-spring systems can become negative in a certain frequency range of the driving force. Here, we look at the behaviour of the system after it reaches a steady state, under the influence of a constant restoring/equilibrium force.