This paper presents a novel wheelchair–exoskeleton hybrid robot that can transform between sitting and walking modes. The lower-limb exoskeleton uses planetary-geared motors to support the hip knee joints. Meanwhile, ankle joints are passive. left right wheel modules be retracted lower legs of prepare for or stepping over obstacles. chair designed form stable posture avoid falling while traveli...

We study countable universes similar to a free action of a group G. It turns out that this is equivalent to the study of free semi-actions of G, with two universes being transformable iff one corresponding free semi-action can be obtained from the other by a finite alteration. In the case of a free group G (in finitely many or countably many generators), a classification is given. Mathematics S...

Abstract. We give a general multiplication-convolution identity for the multivariate and bivariate rank generating polynomial of a matroid. The bivariate rank generating polynomial is transformable to and from the Tutte polynomial by simple algebraic operations. Several identities, almost all already known in some form, are specialization of this identity. Combinatorial or probabilistic interpr...

In order to provide privacy for all the residents, individual rooms are especially important. According to the research, the average size for each individual is only 5m, the size is so limited for daily life, so how to reach the maximum use of the minimum space is discussed, different products of transformable beds, table and chairs were compared. Murphy bed, down folding table and free folding...