In order to further reduce the aerodynamic drag of High-speed Electric Multiple Units (EMU), an active flow control reduction method combining air suction and blowing is proposed at rear EMU train. A numerical calculation based on realizable k-ε used investigate characteristics a three-car with speed 400 km/h. The influence different suction-blowing mass rates, position number ports surface pre...

In a recent paper, the first author proved the log-concavity of the coefficients of the characteristic polynomial of a matroid realizable over a field of characteristic 0, answering a long-standing conjecture of Read in graph theory. We extend the proof to all realizable matroids, making progress towards a more general conjecture of Rota–Heron–Welsh. Our proof follows from an identification of ...

The evolution of self-replication in three dimensions is explored for the first time. A discrete three-dimensional world populated with physically-realizable “molecubes” is simulated. The cubes have randomly initialized controllers, can rotate about an axis, and can attach to one another to form conglomerations. Genetic material, which defines cube controllers, is exchanged stochastically betwe...

We consider bargaining problems that involve two participants, with a nonempty closed, bounded convex bargaining set of points in the real plane representing all realizable bargains. We also assume that there is no definite threat or disagreement point that will provide the default bargain if the players cannot agree on some point in the bargaining set. However, there is a nondeterministic thre...

We show that f -vectors of matroid complexes of realizable matroids are strictly log-concave. This was conjectured by Mason in 1972. Our proof uses the recent result by Huh and Katz who showed that the coefficients of the characteristic polynomial of a realizable matroid form a log-concave sequence. We also prove a statement on log-concavity of h-vectors which strengthens a result by Brown and ...

The fuel optimality of third-body driven plane changes (i.e., plane changes performed by using third-body forces) over one-impulse transfers is investigated numerically and analytically. In particular, the range of third-body driven plane changes that are realizable is shown to be restricted and one impulse must be used in the uncovered regions. However, when third-body driven plane changes are...

Suppose X is a theorem of S4, and a realization for X has been constructed. If X ′ is a substitution instance of X, it is also a theorem of S4, and so is realizable, but the only available algorithm for producing a realization of X ′, so far, has been to apply a general realization algorithm to a cut-free proof of X ′. In effect we start over and the realization of X plays no role. It is the pu...

It is shown that allpole filters of secondand third-order can be significantly desensitized to component tolerances by so-called impedance tapering, i.e., successively impedance-scaling upwards the Lsections of a resistance–capacitance ladder network in the forward and feedback path of a single-amplifier active filter. In order to obtain a realizable filter, certain constraints on the design eq...